Automotive Air Conditioning Information Forum (Archives)

daddyof4js on Tue May 26, 2015 5:49 PM

Year: 2006
Make: Chevrolet
Model: Silverado
Engine Size: 5.3L

My 06 Chevy Silverado has begun experiencing intermittent air conditioning. Upon start-up, the air will blow cold. Once on the road, after a period of time, it will begin blowing warm, muggy air. The aforementioned period of time is not consistent. It might be 15 minutes. It could be 5 minutes. Or even longer. After another period of time, it will begin blowing cold air. Again, there is no consistency to this period of time. Yesterday, it took 45 minutes before the cold air came back. Sometimes it's five minutes. My mechanic is at a loss. They, of course, cannot duplicate the problem. Any educated guesses out there?

GM Tech on Tue May 26, 2015 9:26 PM

Your mechanic doesn't do much a/c if he does not suspect a wide air gap on clutch- verty, very common on higher mileage Chevy trucks and trailblazers/Envoy- just did an Envoy last week- symptoms are always- cold at start up, then warm---well, next time it is warm- touch nothing- pull over and look at compressor nose- is it turning? probably not. The coil gets warm and resistance is too great to pull the clutch driver in over a wider than spec air gap. It you tap on front of clutch, (or hit a bump, or slam the hood real good) the compressor will kick on. Air gaps wear over time and get too wide. The fix is to remove 10mm bolt on front of compressor, and gently remove (wiggle loose) the splined clutch driver- and watch for how many shims are in behind it (shims create the air gap) Remove the biggest shim (or only shim) and put back together and go cool for another 100k miles.

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Bomber65 on Mon June 01, 2015 8:00 PM

This seems to be the problem I am having with a 2004 GMC Sierra. Last year a/c was intermittent and this year it almost never works. Compressor sometimes engages and sometimes just stops. Tapped on the front of the clutch today and the compressor kicked in. About 20 minutes later it went off again. Another whack made it kick back in. So I am suspecting wide air gap. What is the trick to removing the bolt? The pulley is spinning when I try to remove it. Holding on to the pulley while trying to remove this bolt isn't working either. The bolt is very tight. A special tool required other than a 10mm socket and ratchet?

GM Tech on Tue June 02, 2015 8:25 AM

A trick is to "jumper" the a/c relay- which energizes the clutch coil and the belt holds the clutch from turning-- or you can use a "chain vice grip" to hold the driver from turning- either way works for me.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......