JP2000094952A - Air conditioning system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently ensure a coolant and oil necessary for dehumidifying heating operation by providing a structure in such a manner that the coolant and oil carried into an external condenser is removable, and, in starting the dehumidifying heating operation, executing a coolant (and oil) recovering control after cooling operation is performed for a prescribed time. SOLUTION: In front seat and rear seat air conditioning systems 2, 3 comprising evaporators 14, 15 and heater cores 18, 19 provided within air conditioning ducts 4, 5, respectively, a passage part 60 allowing the discharge side of a compressor 50 to communicate with the discharge side of an expansion valve XV1 through an external condenser 49 and a liquid tank 52 is provided. A passage part 62 allowing the discharge side of the compressor 50 to communicate with the discharge side of an orifice 53 as expanding means through a sub-condenser 16 is also provided. A coolant recovering passage 66 is provided between the downstream side of the external condenser 49 and the intake side of the compressor 50, and when air conditioning operation is started, the air conditioning operation is performed for a prescribed time, and a solenoid valve V3 is then opened to recover the coolant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner having a cooling cycle configured so that the flow of refrigerant does not reverse during a cooling operation and a dehumidifying / heating operation.

[0002]

2. Description of the Related Art As a conventional vehicle air conditioner, for example, disclosed in Japanese Patent Application Laid-Open No. 8-99526, a main condenser is arranged outside a vehicle compartment, and a sub-condenser and an evaporator are arranged in an air-conditioning duct. In the cooling operation of the main condenser, the refrigerant is circulated in the order of the main condenser, the sub condenser, the liquid tank, the expansion valve, the evaporator, and the compressor.In the dehumidifying and heating operation, the main condenser is bypassed, and the sub condenser, the liquid tank, the expansion valve, The refrigerant is circulated in the order of the evaporator and the compressor.

In the dehumidifying and heating mode of the vehicle air conditioner having this configuration, the evaporator and the sub-condenser are operated, and the air passing through the evaporator and the sub-condenser is substantially heated by the energy added by the compressor. Therefore, a large heating capacity cannot be obtained. Therefore, in order to further improve the heating capacity, an external heat source, for example, a heater core using engine waste heat as a heat source is provided.

[0004]

However, in the above-described vehicle air conditioner, when operating the dehumidifying and heating operation, it is necessary to increase the amount of the circulating refrigerant in the dehumidifying and heating operation. There is a need to effectively take the refrigerant that has accumulated in the unused external condenser into the cycle.

[0005] Therefore, an object of the present invention is to provide a vehicle air conditioner capable of efficiently taking in refrigerant contained in an external condenser into a cycle.

[0006]

Accordingly, the present invention provides at least a blower, an evaporator,
A sub-condenser, an external heat source heater, a damper for adjusting the amount of air passing through the external heat source heater, a compressor for compressing the refrigerant, and a first valve, provided from the discharge side of the compressor, outside the air conditioning duct. A first passage communicating with a discharge side of the first expansion means via a condenser, a liquid tank, and a one-way valve; and a second passage through a second valve and the sub-condenser from a discharge side of the compressor. A second passage portion communicating with the discharge side of the expansion means, and a compressor via the evaporator and the accumulator from a point where the discharge side of the first expansion means and the discharge side of the second expansion means are connected. A third passage portion communicating with the suction side of the first passage portion, between the external condenser of the first passage portion and the liquid tank, and between the evaporator and the accumulator in the third passage portion. A cooling cycle constituted by a bypass passage opened and closed by a third valve, wherein the first valve is opened and the second valve is closed during the cooling operation, and The first passage portion and the third passage portion communicate with each other from the discharge side to the suction side of the compressor to circulate the refrigerant. During the dehumidifying and heating operation, the first valve is closed and the second valve is opened, and the compressor is opened. A second air passage that communicates with the second passage portion and the third passage portion from a discharge side of the compressor to a suction side of the compressor to circulate the refrigerant and to drive the external heat source heater; A refrigerant recovery passage is provided between the compressor and the suction side of the compressor, and a third valve for opening and closing the passage is provided in the passage.

Thus, a refrigerant recovery passage communicating the downstream side of the external condenser with the suction side of the compressor is provided, and a third valve for opening and closing the refrigerant recovery passage is provided. By opening, the refrigerant stagnating in the external condenser is taken into the cycle by the suction force of the compressor, so that the refrigerant laid down in the external condenser can be used effectively, and the refrigerant required for the dehumidifying heating mode The amount can be secured. Furthermore, since oil remaining in the condenser or the like can be taken into the cooling cycle at the same time as the refrigerant is recovered, burning of the compressor can be prevented, and stable driving can be obtained.

Further, according to the present invention, in the refrigerant recovery control, the cooling operation is performed for a predetermined time when the air conditioner is started.
It is performed only once by opening the third valve. With this, the amount of refrigerant staying in the external condenser at the time of starting the air conditioner can be always kept constant, so that the state of the refrigerant at the time of starting the air conditioner can be kept constant, and appropriate supply of refrigerant can be achieved. In addition to the above, it is possible to easily recover a required amount of refrigerant in the refrigerant recovery control executed as needed. It is desirable that the refrigerant recovery control is executed only once at the time of startup. This is because, if the predetermined condition is satisfied during the normal air-conditioning control, the execution of the refrigerant recovery control is likely to hinder the normal air-conditioning control.

Further, when the heat source of the external heat source heater is engine cooling water, whether the engine cooling water supplied to the external heat source heater is below a predetermined temperature is determined by whether or not the temperature is below a predetermined temperature.
It is desirable to determine whether or not it is during startup. As a result, the initial startup can be easily detected.

Further, it is desirable to execute the refrigerant recovery control when the outside air temperature is equal to or lower than a predetermined temperature. As a result, the dehumidifying and heating operation can be reliably determined, so that the refrigerant recovery control can be executed efficiently.

Further, it is desirable to stop the operation of the blower during the cooling operation performed at the beginning of the air conditioning control start. Since it is possible to prevent the cool air from blowing out when the dehumidifying heating is required, it is possible to prevent the occupant from feeling uncomfortable.

Further, the vehicle air conditioner further comprises an external condenser temperature detecting means for detecting a temperature of the external condenser, a low-pressure refrigerant temperature detecting means for detecting a temperature of the low-pressure refrigerant sucked by the compressor, and Temperature comparison means for comparing the external condenser temperature detected by the condenser temperature detection means with the low-pressure refrigerant temperature detected by the low-pressure refrigerant temperature detection means, and the external condenser temperature is lower than the low-pressure refrigerant temperature by the temperature comparison means. Is determined to be high, the third valve is opened to recover the refrigerant, and if the temperature of the external condenser is determined to be lower than the low-pressure refrigerant temperature by the temperature comparison means, the third valve is recovered. Is closed to prevent the backflow of the refrigerant.

When the temperature of the external condenser is high, the refrigerant flows to the suction side of the compressor, but when the temperature of the external condenser is low, the refrigerant condenses on the external condenser and the pressure on the external condenser decreases. Since the refrigerant may flow backward, the third valve is closed to prevent the refrigerant from flowing backward.

When the third valve is set to be open, it is desirable to drive a fan for ventilating the external condenser. Thereby, heat exchange by the external condenser is promoted, and the temperature of the refrigerant sucked from the external condenser rises, so that the heating efficiency in the dehumidifying and heating mode can be improved.

Further, it is preferable that the third valve is normally open. As a result, even in the stopped state, the refrigerant and the oil flow into the external condenser side and are stabilized, so that the compressor can be prevented from being damaged even when operated in the refrigerant mode at the time of startup.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a vehicle air conditioner according to an embodiment of the present invention. The vehicle air conditioner 1 includes a front seat air conditioner 2 and a rear seat air conditioner 3. The vehicle air conditioner 1 is mounted on a vehicle in which engine waste heat is not sufficiently expected as a heating heat source, for example, a hybrid vehicle or a direct injection engine vehicle.

The front seat air conditioner 2 comprises an air conditioning duct 4
And an outside air inlet 6 and an inside air inlet 8 that are opened on the most upstream side of the air conditioning duct 4, and an intake door 10 that selectively and selectively opens the outside air inlet 6 and the inside air inlet 8. Downstream of the intake door 10, a front seat blower 12 is provided.
An evaporator 14 (for a front seat) and a sub-condenser 16 are arranged downstream of the vehicle. Further, on the downstream side of the evaporator 14 and the sub-condenser 16, an external heat source heater (front seat heater core) 1 using engine waste heat as a heat source is provided.
8 is provided on the upstream side of the front seat heater core 18 to divide the air passing through the evaporator 14 and the sub-condenser 16 into the air passing through the front seat heater core 18 and the bypass air. Mixed door 2
0 is provided. Further, at the most downstream side of the air conditioning duct 4, a differential air outlet 22, a vent air outlet 24, and a foot air outlet 26 are opened, and a corresponding mode door 2 is provided.
Openings are provided at 8, 30, and 32 as appropriate.

The rear seat air conditioner 3 includes an air conditioning duct 5.
And an inside air inlet 7 opening to the most upstream side of the air conditioning duct 5, and a blower 13 arranged downstream of the inside air inlet 7.
And a rear seat evaporator 15, a rear seat air mix door 21, and an external heat source heater (rear seat heater core) 19 disposed downstream of the blower 13, and a most downstream side of the air conditioning duct 5. Has an opening 23 in the vehicle interior.

Further, the vehicle air conditioner 1 includes various control devices such as the front seat blower 12 and the rear seat blower 1.
3. Intake door drive actuator 40, front seat air mix door drive actuator 41, mode door drive actuator 42, rear seat air mix door drive actuator 43, and a compressor 50 for a cooling cycle described below, not shown. It has a control unit 44 for driving and controlling a condenser fan and the like. The control unit 44 receives various input signals via an A / D converter 45 and a multiplexer (MPX), for example, an outside air temperature Tamb, an inside air temperature Tinc, an engine cooling water temperature Tw, a suction air temperature Tair, and an external condenser outlet. At least the side refrigerant temperature Tcond, the compressor low pressure Ps, the condenser fan signal CONDFAN, and the like are input and calculated together with the setting signals from the front-seat side operation panel (main panel) 47 and the rear-seat side operation panel 48 to perform the above-described control. This is converted into an appropriate control signal for driving the device.

The cooling cycle according to the embodiment of the present invention shown in FIG. 2 includes a first solenoid valve V1 from the discharge side of the compressor 50 and an external condenser 4 provided outside the air conditioning duct.
9, a first passage portion 60 communicating with the receiver tank 52, the one-way valve V0 and the outlet side of the first expansion valve XV1 as the first expansion means, and a second passage portion from the discharge side of the compressor 50. A second passage portion 62 communicating with the solenoid valve V2, the sub-condenser 16, and a discharge side of an orifice 53 as a second expansion means, and a discharge side of the first expansion valve XV1 and the orifice 53 are connected. A third passage portion 64 communicating from the evacuation point to the suction side of the compressor 50 via the front seat evaporator 14 and the accumulator 51, between the external condenser 49 of the first passage 60 and the liquid tank 52, and The third passage 64 communicates between the evaporator 14 and the accumulator 51,
And a bypass passage 66 which is opened and closed by the solenoid valve V3. In this cooling cycle, 55 is a pressure sensor for detecting the compressor low pressure Ps, 5
6 is a temperature sensor for detecting the temperature Tw of the engine cooling water as an external heat source, 57 is a temperature sensor for detecting the external condenser outlet side refrigerant temperature Tcond, 58 is an external air temperature Tamb disposed near the external condenser. This is a temperature sensor to be detected. Instead of the temperature sensor 57, a pressure sensor that detects an external condenser outlet pressure Pcond may be used, and the external condenser outlet refrigerant temperature Tcond may be calculated from the external condenser outlet pressure Pcond. is there. Further, the external condenser outlet temperature Tcond may be obtained by calculation from the outside air temperature Tamb from the outside air temperature sensor 58 without particularly providing the sensor 57 for detecting the external condenser outlet side temperature (for example: Tcond = Tamb + β).

In the cooling cycle, as a cooling device for the rear seat air conditioner 3, a rear seat side passage portion 68 communicating the inflow side of the one-way valve V0 and the downstream side of the front seat evaporator 14 is provided. The rear-seat side passage portion 68 is provided with a rear-seat expansion valve XV2 and a rear-seat evaporator 15 in series, and a fourth expansion valve XV2 provided upstream of the rear-seat expansion valve XV2. The supply of the refrigerant is controlled by the solenoid valve V4.

The air-conditioning control executed by the control unit of the vehicle air-conditioning system 1 having the above-described configuration is shown in, for example, the flowcharts of FIGS. 3 to 6, and the air-conditioning control will be described below with reference to this flowchart.

The main control routine shown in FIG. 3 is started when an ignition switch (not shown) is turned on. In a signal processing operation block of step 100, signals from the above-mentioned sensors and the like are sequentially taken into predetermined control factors. It converts and converts the heat load signal (target blowing temperature, total signal, etc.) as a reference for air conditioning control as needed.

Then, in step 200, operation mode setting control is executed. This operation mode setting control is shown in FIG.
It is determined whether or not the outside air temperature Tamb is equal to or lower than a predetermined temperature. Specifically, the first predetermined temperature t1 (for example, 0
° C) and a second predetermined temperature t2 (for example, 5 ° C), which is determined in accordance with a characteristic line in which hysteresis is formed. In the above case, “B” is set. When the initial value is between t1 and t2, the determination “A” is set with priority.

The setting in step 210 is determined in step 220. If the determination is "A", the process proceeds to step 230. If the determination is "B", the process proceeds to step 3.
Go to 50. In step 350, the first solenoid valve V1 is set to open and the second solenoid valve V2 is set to close to execute the cooling operation. In step 370, the operation mode "1" is set.

In step 230, the temperature Tw of the engine cooling water is determined. Specifically, the third
The predetermined temperature t3 (for example, 67 ° C.) and the fourth predetermined temperature t4
(For example, 72 ° C.) is determined according to a characteristic line in which hysteresis is formed. When the temperature is lower than a predetermined temperature, “C” is set, and when the temperature is higher than the predetermined temperature, “D” is set. Is set. When the initial value is between t3 and t4, the determination “C” is set with priority.

The setting in step 230 is determined in step 240. If the determination "C" has been set, the process proceeds to step 360. If the determination D has been set, the process proceeds to step 350. To go to. Thus, if the water temperature Tw is equal to or higher than the predetermined temperature, the cooling operation is set in step 350, and if the water temperature Tw is equal to or lower than the predetermined temperature, step 3 is performed.
Proceeding to 60, the first solenoid valve V1 is closed, the second solenoid valve V2
Is set to open and the dehumidifying heating mode is executed, and the routine proceeds to step 380, where the operation mode "2" is set. Then, the process returns from step 390 to the main control routine.

Next, in step 300, start-up initial control is executed. This startup initial control is shown in FIG. 5. First, in step 310, it is determined whether or not the starting of the driving engine and the turning on of the ignition switch which is a switch of the electric circuit is the first time. In this determination, if the ignition switch has not been turned on for the first time, the process proceeds to step 395 to exit this control. If the ignition switch (IG) has been turned on for the first time, the process proceeds to step 320, where the operation mode described above is set. A determination is made. In this determination, if the operation mode “1” is set, the process proceeds to step 395 and exits from this control as in the case described above.

In this way, when the operation mode is the cooling mode, the initial startup control is not required, and the control exits from this control. If it is determined in step 320 that the operation mode "2" is set, Especially the capacitor 4
Since it is necessary to collect the refrigerant and oil that are assumed to be accumulated in the air conditioner 9, the process proceeds to step 330, where the first solenoid valve V1 is opened and the second solenoid valve V2 is closed to set the air conditioner. Set 1 to cooling mode. In the case of the cooling mode set at the initial stage of startup, the rear seat air conditioner 3
Therefore, it is desirable that the fourth solenoid valve V4 is closed and only the front seat air conditioner 2 is set to the cooling mode.

Then, in step 340, the operation of the blower 12 for the front seat is stopped (the FAN speed is zero). This prevents the cooled air from being unnecessarily blown out to the occupant, and activates the compressor 50 in step 350 (COMP ON).

After the operation of the compressor 50, the timer t is started in step 360 and the timer t is counted. In step 370, it is determined whether or not a predetermined time α has elapsed. If it is determined in step 370 that the predetermined time α has not elapsed, the process returns from step 395 to the main control routine and proceeds to the next step. If the predetermined time α has elapsed in the determination of step 370, In step 380, the timer t is reset, and in step 390, the compressor 50 is stopped (COMP OFF). Then, the process returns from step 395 to the main control routine.

In the start-up initial control described above, by operating the cooling mode for a predetermined time, the refrigerant is supplied to the external condenser 49, the liquid tank 52 and the evaporator 14
Is circulated for a predetermined time.
When the operation is stopped, the external capacitor 49 and the liquid tank 52
Since the amount of the refrigerant staying in the evaporator 14 can be always kept in a predetermined state, it is possible to easily grasp the state of the refrigerant in the cycle, so that the adjustment of the amount of the refrigerant in the subsequent operation mode can be easily performed. Is what you can do.

After the start-up initial control in step 300, refrigerant recovery control (and oil recovery control) is executed in step 400. This refrigerant recovery control is, for example, as shown in FIG. 5. First, at step 410, it is determined whether or not the operation mode “1” has been set. When it is determined that the operation mode “2” is set by this determination, it is determined that the heating mode or the dehumidification heating mode is set, and it is determined that the outside air temperature operation mode “1” is set. If so, it is determined that the cooling mode is set. If the result of this determination is that the cooling mode is to be set, there is no need to recover the sleeping refrigerant, so the process proceeds to step 450 to close the third solenoid valve V3 and close the bypass passage 66. Things.

Further, at step 420, it is determined whether or not the compressor 50 is operating. If the determination at step 410 indicates that heating is required and the compressor 50 is not operating, for example, the normal heating mode Is required, there is no need to recover the stagnation refrigerant, so the routine proceeds to step 450, where the third solenoid valve V3 is closed.

In the next step 450, the low-pressure refrigerant temperature Ts calculated from the compressor low-pressure pressure Ps is compared with the external condenser outlet-side refrigerant temperature Tcond. In this determination, the external condenser outlet side refrigerant temperature Tcond
Is higher than the low-pressure refrigerant temperature Ts, the routine proceeds to step 440, where the third solenoid valve V3 is opened to draw the stagnant refrigerant retained in the external condenser 49 to the suction side of the compressor 50 and circulate. It is intended to be taken in. If the external condenser outlet refrigerant temperature Tcond is lower than the low-pressure refrigerant temperature Ts, the routine proceeds to step 350, where the third solenoid valve V3 is closed, and the refrigerant flows backward from the low-pressure side of the compressor 50 to the external condenser 49 side. It is to prevent that. It should be noted that this backflow phenomenon is caused by the fact that when the temperature inside the external condenser 49 is low, the refrigerant condenses inside the external condenser 49 and the pressure inside the external condenser 49 becomes lower than the low pressure of the compressor 50. Presumed.

If the third solenoid valve V3 is opened in step 440, the process proceeds to step 370, in which a fan that ventilates the external condenser 49, for example, a fan (RADF) called a condenser fan or a radiator fan is used.
AN) (not shown) to increase the heat absorbing effect of the refrigerant in the external condenser 49, to increase the temperature of the refrigerant sucked into the suction side of the compressor 50, and to assist the heat release in the sub-condenser 16. It is to be.

When the third solenoid valve 350 is closed in step 450, it is determined in step 460 whether or not a radiator fan signal (RADFAN) is present. Step 4
Proceeding to 70, the above-described radiator fan (not shown) is operated (RADFAN ON), and if there is no radiator fan signal, the process proceeds to step 380 to stop the radiator fan (RADFAN OFF). Then, the process returns from step 490 to the main control routine.

As described above, in the operation mode setting control from step 200, the operation mode of the cooling operation or the dehumidifying / heating operation is set based on the outside air temperature Tamb and the engine cooling water temperature Tw. Is executed, and the refrigerant containing oil is caused to flow through the path of the external condenser 49 and the liquid tank 52, so that the refrigerant is forced to lie in this path, and then the refrigerant recovery control from step 400 is executed. Therefore, the refrigerant and the oil can be reliably recovered. In addition, since the radiator fan is operated at the time of the recovery control of the stored refrigerant and the oil, it is possible to assist the heating of the refrigerant by the external condenser 49.

In the main control routine, based on the above-mentioned heat load signal, the air mixing door control is performed in step 500, and the compressor 50 is controlled in step 600.
On / off control or capacity control of
At 00, mode door control for opening and closing the air outlets 22, 24, 26 is performed. At step 800, intake door control for selecting intake air is performed. At step 900, the blowers 12, 13 are controlled.
Are sequentially executed, and the process returns to step 200.

Further, it is desirable to use a normally open solenoid valve as the third solenoid valve V3. Accordingly, when the operation of the air conditioner 1 is stopped, the refrigerant and the oil flow into the external condenser 49 and fall asleep. Therefore, even if the air conditioner 1 is operated in the cooling mode when the air conditioner 1 is started, the compressor 50 can be prevented from being damaged. is there.

[0042]

As described above, according to the present invention, a structure is provided in which the refrigerant and the oil stored in the external condenser can be recovered, and after starting the dehumidifying and heating operation, the cooling operation is performed for a predetermined time. Refrigerant (and oil)
Since the recovery control is executed, the refrigerant and the oil required during the dehumidifying and heating operation can be efficiently secured. In addition, since the external condenser is ventilated at the time of the initial control of the startup, the heat of the outside air can be positively taken into the refrigerant, so that the heat radiation amount of the heating can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a cooling cycle according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating a main control routine of air conditioning control according to the present invention.

FIG. 4 is a flowchart showing an operation mode setting control of the air conditioning control of the present invention.

FIG. 5 is a flowchart showing the initial control of the air conditioning control according to the present invention.

FIG. 6 is a flowchart illustrating refrigerant recovery control of the air conditioning control of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle air conditioner 2 Front seat air conditioner 3 Rear seat air conditioner 4 Air conditioning duct 5 Rear seat air conditioning duct 14 (For front seat) Evaporator 15 Rear seat evaporator 16 Subcondenser 18 (For front seat) Heater core 19 Rear Heater core for seat 49 External condenser 50 Compressor 51 Accumulator 52 Receiver tank

Claims (8)

[Claims] An air conditioning duct having at least a blower, an evaporator, a sub-condenser, an external heat source heater, a damper for adjusting an amount of air passing through the external heat source heater, a compressor for compressing a refrigerant, and a discharge of the compressor From the side, the first valve, the condenser provided outside the air conditioning duct, the liquid tank and the one-way valve through the first
A first passage portion communicating with the discharge side of the expansion means, and a second passage portion communicating from the discharge side of the compressor to the discharge side of the second expansion means via the second valve and the sub-condenser. The discharge side of the first expansion means and the second expansion means;
A third passage portion communicating from the point where the discharge side of the expansion means is connected to the suction side of the compressor via the evaporator and the accumulator, between the external condenser of the first passage portion and the liquid tank; A cooling cycle formed by a bypass passage portion that communicates between the evaporator and the accumulator in the third passage portion and that is opened and closed by a third valve; Is closed, and the first passage portion and the third passage portion are communicated from the discharge side of the compressor to the suction side of the compressor to circulate the refrigerant. The second valve is opened to open the second valve from the discharge side of the compressor to the suction side of the compressor.
In the vehicle air conditioner that circulates the refrigerant by communicating the passage portion and the third passage portion and drives the external heat source heater, the refrigerant is disposed between the downstream side of the external condenser and the suction side of the compressor. An air conditioner for a vehicle, comprising a recovery passage, and a third valve for opening and closing the refrigerant recovery passage. 2. The refrigerant recovery control is executed only once by starting a cooling operation for a predetermined time and then opening a third valve when the air conditioner is started. The air conditioner for a vehicle according to claim. 3. When the heat source of the external heat source heater is engine cooling water, it is determined when the temperature of the engine cooling water is equal to or lower than a predetermined temperature when the air conditioner is started. 3. The vehicle air conditioner according to 2. 4. The vehicle air conditioner according to claim 2, wherein the refrigerant recovery control is executed when an outside air temperature is equal to or lower than a predetermined temperature. 5. The air conditioner for a vehicle according to claim 2, wherein the operation of the blower is stopped during a cooling operation performed during the refrigerant recovery control. 6. The vehicle air conditioner further comprises: an external condenser temperature detecting means for detecting a temperature of the external condenser; a low-pressure refrigerant temperature detecting means for detecting a temperature of a low-pressure refrigerant sucked by the compressor; Temperature comparison means for comparing the external condenser temperature detected by the external condenser temperature detection means with the low-pressure refrigerant temperature detected by the low-pressure refrigerant temperature detection means, and the external condenser temperature is reduced by the low-pressure refrigerant temperature by the temperature comparison means. If it is determined that the temperature is higher than the third pressure, the third valve is opened to recover the refrigerant, and if the temperature of the external condenser is determined to be lower than the low-pressure refrigerant temperature by the temperature comparing means, the third valve is opened. The vehicle air conditioner according to any one of claims 1 to 5, wherein the valve is closed to prevent backflow of the refrigerant. 7. The vehicle air conditioner according to claim 6, wherein when the third valve is set to be open, a fan for ventilating the external condenser is driven. 8. The vehicle air conditioner according to claim 1, wherein the third valve is normally open.