Ac Clutch

[NikolinaJ]

Hi,

Can somebody please tell me what is the cause of a AC clutch turning all the time when AC is on? And if that can be fixed. Thanks

[RFeldes]

That is called an engaged clutch and is normal while running the AC.

[wwest]

Hi,

Can somebody please tell me what is the cause of a AC clutch turning all the time when AC is on? And if that can be fixed. Thanks

With the A/C "on", enabled, there are only a few things that will result in the compressor clutch being disengaged.

1. Refrigerant pressure too low...generally meaning low on refrigerant.

2. Refrigerant pressure high.....normal occurrance.

3. Evaporator temperature too close to freezing.

4. OAT below about 35F

5. WOT.

6. Engine coolant temperature too high.

Running continuously might mean the system is heavily loaded, liquid refrigerant is being exhausted as fast as it can be compressed/pumped, HOT day, bright sunshine, 4+ passengers, black exterior/interior, open windows, etc. Or it might also mean the refrigernat level is marginal.

[NikolinaJ]

Ok thanks. I took the car to the shop and they recharged it and put a die in and there is no leaks but it still doesn't work. As soon as I turn the AC on clutch engages and as I understand it is suposed to go on and off but it doesn't it turns all the time. I can hear the clicking sound coming from the compressor. I checked the belt and it's in a good condition. Do you think I need a new compressor? And can you please tell me what is WOT?

Hi,

Can somebody please tell me what is the cause of a AC clutch turning all the time when AC is on? And if that can be fixed. Thanks

With the A/C "on", enabled, there are only a few things that will result in the compressor clutch being disengaged.

1. Refrigerant pressure too low...generally meaning low on refrigerant.

2. Refrigerant pressure high.....normal occurrance.

3. Evaporator temperature too close to freezing.

4. OAT below about 35F

5. WOT.

6. Engine coolant temperature too high.

Running continuously might mean the system is heavily loaded, liquid refrigerant is being exhausted as fast as it can be compressed/pumped, HOT day, bright sunshine, 4+ passengers, black exterior/interior, open windows, etc. Or it might also mean the refrigernat level is marginal.

[wwest]

Ok thanks. I took the car to the shop and they recharged it and put a die in and there is no leaks but it still doesn't work. As soon as I turn the AC on clutch engages and as I understand it is suposed to go on and off but it doesn't it turns all the time. I can hear the clicking sound coming from the compressor. I checked the belt and it's in a good condition. Do you think I need a new compressor? And can you please tell me what is WOT?

Hi,

Can somebody please tell me what is the cause of a AC clutch turning all the time when AC is on? And if that can be fixed. Thanks

With the A/C "on", enabled, there are only a few things that will result in the compressor clutch being disengaged.

1. Refrigerant pressure too low...generally meaning low on refrigerant.

2. Refrigerant pressure high.....normal occurrance.

3. Evaporator temperature too close to freezing.

4. OAT below about 35F

5. WOT.

6. Engine coolant temperature too high.

Running continuously might mean the system is heavily loaded, liquid refrigerant is being exhausted as fast as it can be compressed/pumped, HOT day, bright sunshine, 4+ passengers, black exterior/interior, open windows, etc. Or it might also mean the refrigernat level is marginal.

WOT, Wide Open Throttle, kill the A/C all power to the roadbed.

[Robert Young]

If your system cycles the AC clutch based on a pressure switch, that might be defective. For the LS 430, the AC pressure sensor feeds into the AC control assembly (computer), so it is not directly linked into the circuit that operates the AC compressor clutch like lesser cars (our old Ford Taurus comes to mind). I'd look into the Lexus /Toyota site: http://techinfo.toyota.com/ for the appropriate repair instructions for your car, I think they still charge $10 to download all you want over 24 hours.

You may want to put a pressure guage at the low pressure side and see if it indicates that the compressor should be off. In a normal system for the LS 430 the low pressure side should be 0.15 to 0.25 MPa (approx. 22 - 37 psi) and the high pressure side should be 1.37 to 1.57 MPa (approx. 202 - 231 psi).

[wwest]

If your system cycles the AC clutch based on a pressure switch, that might be defective. For the LS 430, the AC pressure sensor feeds into the AC control assembly (computer), so it is not directly linked into the circuit that operates the AC compressor clutch like lesser cars (our old Ford Taurus comes to mind). I'd look into the Lexus /Toyota site: http://techinfo.toyota.com/ for the appropriate repair instructions for your car, I think they still charge $10 to download all you want over 24 hours.

You may want to put a pressure guage at the low pressure side and see if it indicates that the compressor should be off. In a normal system for the LS 430 the low pressure side should be 0.15 to 0.25 MPa (approx. 22 - 37 psi) and the high pressure side should be 1.37 to 1.57 MPa (approx. 202 - 231 psi).

In H&H, HOT & HUMID, Memphis last week with my brother's 91 LS400 the only way I was able to get the compressor clutch to cycle off, and/or the electric radiator cooling fans to cycle on, was to first cool down the interior atmosphere in recirculate mode and then reduce the blower speed to minimum to reduce the rate at which the refrigernat was being "burned off" via otherwise "warm" airflow through the evaporator.

Temperature was in the ninties so "fresh" mode meant 90F incoming airflow and RAPID refrigerant evaporation.

It took 48 ounces of R-134a to get to that point.

Other than the compressor constantly engaged if the system is cooling well then I'm not sure I would worry overly much.