Hello everybody

I have a problem with my A/C compressor of my 00 Jimmy. It continuously on/off only while acceleration but when the car in idle it keeps working great and cool without switching on/off.

What can be the problem from ?


thank you

 

What happens at high steady rpm?

George

 

Hi George

I check that when the car in idle with steady1500 RPM for more than 30 sec a/c compressor clutch never disengage. But while car accelerate a/c compressor clutch continue switching on/off.


thank you

 

1. At what rpm does the clutch disengage?
2. How do you know this while you are accelerating?
3. Does the accelerator pedal have to be at the floor?

George

 

1. Actually, there is no specific rpm make clutch disengage.

2.When it is no longer cool air for 15 sec and then it blow cool air. Also, rpm go up instantly when the compressor clutch disengage.

3.Yes, specially after clutch engage.

thank you

 

Q&A is over, what's the answer

 

I don’t know the answer yet, hence the Q&A. Here are the possibilities:

1. some vehicles turn the compressor off under hard acceleration, not sure about this on all years of our Blazers, manual/automatic
2. The system is overcharged and/or there is a partial refrigerant circuit restriction and stronger compressor performance trips the high pressure switch
3. A restriction causes the low side to drop and that sensor to trip
4. The compressor clutch is weak and let’s go under stress
5. There is a wiring fault possibly combined with a broken motor mount and the torque under hard acceleration breaks the circuit by moving the wiring harness
6. There is a loss of vacuum and actuators are moving. The most dramatic would be the blend door but I think your blend door actuator is electric (maybe Christine can confirm) but the recirc is vacuum so it depends on the outside temp

The first thing I would do is run some leads from the power connector at the compressor to a meter and see if it loses power during an event. Also if it does it in park watch the clutch in the driveway under a throttle snap. If the clutch shuts off get a set of gauges on the system and watch the pressures. If you don’t have gauges, jumper the high and low pressure switches in turn for one event only to avoid system damage.


George

 

Hello George


Today I check the pressure with my gauge and it is show 35 psi and the temp outside was 34C I add a little freon until it reach 38 psi but still same problem happen the clutch engage all the time at idle but when I shift to drive it works until I increase the speed over 20Km/h it start random engage and disengage.

It is possible that there is a problem in the clutch gap ?

Thank you

 

Your pressures are too low. At 34C/93F ambient your low side pressures should be around 50 psi. The low side switch cuts out in the 3x psi range. The system is designed to cycle especially as the cabin load goes down near the target cabin temp. It can be low charge but also other causes like a weak compressor or a metering device restriction, that is why you should monitor low and high side pressures along with center vent temp to fully assess a system:




George

 

Thank you very much George you are correct it was low freon. Actually, I should expect this from beginning because last time I recharge the system before 5 years when I replace the a/c compressor .