Warm A/C Again.. diagnose?

Aenyone · Aenyone's Garage

Ok. Just had the auto shop pull and refill my compressor a few weeks ago. I had done some work under the car around the compressor and the car was blowing warm, so I wanted them to check for leaks in the process. No leaks at the compressor. It blew cold.
Now it's blowing warm, barely above the outside temp.
I have checked my vacuum lines, the heater control valve, barn doors are closing. Everything looks good.
I also went to check the infamous heater clips that break. They are connected well, but they don't move. Does that mean they are stuck in heat mode?

What do I check to see why the arms aren't moving?

Thanks!

mattdavis11 · 10-26-2011, 07:19 PM

You have to find the leak. Could be a schrader valve or an oring, might be the shaft seal.

How quickly did it lose refrigerant?

Aenyone · Aenyone's Garage

Well, the shop said there was no leak. They used dye.. unless it is leaking elsewhere.
I am a bit concerned that the heater flaps don't work... kinda looking for troubleshooting that.

phoenix_iii · 10-27-2011, 07:03 PM

Flaps - go to clarks-garage. Easy fixes for the most common stuff (clip, etc)

Aenyone · Aenyone's Garage

The flap clips are connected. They just don't move.. It seems that they are controlled by a set of vacuum lines on the other side of the a/c unit, beside the glovebox. Is that accurate?

9FF · 10-28-2011, 06:45 AM

Check the vacuum at the accumulator next to the battery. It is fed from the brake booster valve which does fail from time to time. It won't affect the brakes but it will cause problems with heater and AC controls.

mattdavis11 · 07:51 AM

I think you are headed in the wrong direction. Seriously, it was blowing warm (did you open the system?), a shop checked it out, it blew cold and now warm again.

It had a leak before you took it to the shop, or you discharged it. You didn't discharge it unknowingly, trust me. If they didn't find a leak, they overlooked it, could not see one, or did not know what they were doing. Here's a senario (probably why they said it doesn't leak), when they pulled a vacuum, it held. They said they found no leak, so they charged it up. How they can be fooled: 1) they had their equipment connected to the service ports which would not allow them to diagnose a leaking schrader valve. 2) When under vacuum either the shaft seal, or any oring, sucked itself back into a position where it would hold vacuum. When charged, the seal returns to a leaking condition due to pressure. They can't see dye when it's a slow leak at the shaft seal unless they remove the clutch assembly, nor can they see a small o-ring leak at the expansion valve. It won't spit out enough dye to be seen in the condensate exiting from the evaporator drain tube.

Here is an easy test. Start the car and turn on the a/c. Take a flash light and look at the clutch on the compressor, is the front of it spinning with the pulley? Is it at rest?

At rest=leak, spinning=you might be on the right track. Do you have a/c gauges?

9 out of ten times with a 944, it is the shaft seal on the compressor. Sometimes it's obvious, you will see oil and or grime coating the body of the compressor. Sometimes it's not so evident, ie. a small leak.

I've seen a lot of compressors that will hold both vacuum and pressure, but when engaged, they leak. When that occurs you are most likely dealing with a shaft seal failure, or the shaft has a grove in it where the seal rides.

Verify that the compressor is engaging.