95 Del Sol S. R-134 A/C System.

For quite a while now my a/c would work fine for a while and then all of a sudden the compressor clutch would disengage and the idle would bounce between 900 and 1400 rpm (approx) until it eventually kicked back on again and all was well. I thought maybe it was undercharged and so got a can with a pressure gauge and popped it on. After running for a minute the pressure dropped to around 20psi and so I began to fill it. However, once I got up to around 35psi the clutch started cycling on and off rapidly and then eventually I was back to the clutch disengaged with the motor rpm cycling. Now the a/c hardly runs for any period of time before the compressor shuts off.

I am about to break down and take this car to a shop, but am trying one last time to find someone with some insight. I have no CELs and just replaced the throttle body gasket and cleaned out the iacv and fitv as well. Base idle was set at 500 and then the computer was reset.

Thank you so much for your help.

 

After some reading I believe I may have overcharged it? Granted, it still was not working correctly before I added freon.

 

That's exactly what happened. You have too much refrigerant pressure now. Go get it evacuated and recharged. It's normal for the compressor clutch to disengage and engage. It's not supposed to be constantly engaged unless your max ac all the time, but even then it will disengage periodically.
It sounds like your problem is just related to your idle. Is your tps set and all that usual stuff?

 

Not exactly the best approach, but I went and let some out. Now its back to what it was doing before. Runs for a while and then cuts out. When it cuts out (for several minutes or longer) the air obviously no longer blows cold (how I know it cut out) and I know when I let it idle again the rpm will be fluctuating. I did just notice if I rev the motor up a few times it usually goes back to normal again for a little bit. I checked the TPS and it is linear, however I cannot remember if I checked it at operating temp or not.

 

I know it cycles on and off, but it should not allow the air to stop blowing cold and make the engine bounce between 900 and 1400 rpm over and over and over and over and...

 

I just do not have enough understanding of how everything is controlled to understand what would cause the idle to bounce when the compressor clutch decides to disengage and why revving the motor would cause things to start working again.

 

Correction...revving no longer works. I ran my ac for about 5 minutes and then it stopped engaging and the bouncing began. Also, the rpm bounce is between 1100 and 1400 rpm. The motor also decided to sit at 1500 a few times and 2000 a few times. Could the IACV be having issues? I did just flush it out with carb cleaner but maybe its just bad? I will recheck the tps also soon hopefully.

 

Does your compressor clutch + condensor fan both run when you have the A/C on?

 

The fan is on. The clutch might stay engaged for a few minutes, but then disengages like I said before. Once it disengages the idle bounces.

 

I had this exact issue. Take it to an ac shop and have them service the system. Trust me it worth paying the money for less headaches.

 

What did it wind up being? Just evacuated and charged?

 

Servicing. I was putting to much into the system I think. And all the times I checked the servicing air got into the lines. Also the computer know when ac is selected, it brings up the idle to counter act the additional load. When that load isnt there the idle is all screwy atleast mine was.

 

1) You need to measure refrigerant pressures on both the high and low sides using a manifold gauge set.

2) Check whether the condenser is clogged with bugs etc., which will impede cooling of the refrigerant.

 

Thanks for all the input so far everyone. I guess I will take it in and have it looked at.