A/C compressor doesnt kick in

[skrying26]

When i set my temperature control for the lowest temperature, the a/c compressor should kick in.. I don't notice any change in the rpm.. So i'm guessing the compressor isnt engaging. There is no cold air out of the system either.. The a/c light is on too...

Anyone have any ideas what might cause the compressor to not engage? I have an aftermarket head unit installed as well, but i dont think that should have any bearing on my climate controls.. Is there a fuse somewhere i should check?

[Wacko]

My 2001 compressor is very quiet so it is difficult to tell. I had to visibly inspect the compressor clutch from above to determine if it was indeed turning.

It is likely you have a low refrigerant condition that causes a low pressure condition. This in turn causes the low pressure switch to prevent the compressor from engaging (so as not to burn the thing up.)

I went to Autozone here in the States and picked up a pressure gage and a 15oz can of R134a (plus PAG oil, red leak dye, leak stop, seal conditioner) all in one. It sounds like a gimmick but it was short money. If you choose to do this yourself, read the directions carefully on the can and gage.

I was able to check the pressure and add the can. This took about 45 minutes for the system to consume the 15 ounces. The temp at the vents went from 65 down to about 44 degrees F slowly. But I noticed that the passenger side was blowing colder than the driver's side.

The capacity of the system is 2 lbs. (or 32 ounces) and the service manual talks about low refrigerant as a cause of this symptom. I am going to add the second can and see what I get.

The red dye is helpful in finding leaks in the system. So, we'll see how it goes.

Hope this helps you.

[Marc]

Be very careful when adding any part of the second can.
Overfilled A/C can be as bad as underfilled A/C.

[skrying26]

So the a/c system should be at 2lbs on the gague? If its lower, that means i have to add some refridgerant? And possibly find the leak..

[Marc]

The A/C gauge should not show 2 lbs. when completely filled. 2lbs. is merely the weight of the R-134A that the system takes.
A/C pressures depend on air temperature & humidity as shown in the below chart from the 2001 shop manual.
For example, on a day with 90* temp & at least 60%
humidity, a completely filled 2001 Aurora A/C system should be at 51 - 57 psi on the low side, and 199 - 229
psi on the high side.
To find the leak, you need a leak detector. You move it around the entire A/C system, and when it finds the leak, it will make a rapid beeping sound.

[skrying26]

Perfect, thanks for the information.. I went to a few stores today to see if they sold the refridgerant, and i'm gathering you cant buy it off the shelf here in canada.. Looks like i'll have to book an appointment with the mechanic next week..

Thanks for all your help. ;D

[Marc]

OK!

[BNICOV]

What's the temp outside?? It has to be 15deg Celsius (around 55 or so Far) for the compressor to engage.

[Marc]

According to pg. 1-231 of the 2001 shop manual, the A/C compressor will not turn on below 42* Farenheit....6* Celcius.

[BNICOV]

Thanks for the correction Marc, I knew it had to be above freezing by a few degrees.

[Marc]

OK!

[skrying26]

It was 22 Celcius the day i tried. I didn't notice an rpm chance when i turned the a/c on.. So my guess is the compressor isn't engaging... Oh well, its off to the mechanic on saturday to figure out whats wrong.

[Wacko]

You might not see a change in RPM. Mine doesn't. If you peek down along the front passenger side you should be able to tell if the clutch has engaged. Oh, I said that above already. I'm tired.