Mystery Solved! The Amazing Detective Story of why the car AC failed

What I work [When I worked] for Chevrolet, all of us there at that certain dealer they [that] replace those clutches did the update. We did that because we didn't want it to come back and I have to do it again because we didn't reprogram. It's a very simple thing to reprogram. They [meaning my dealer mechanics] did not do it either because they're lazy or they're uninformed about the problem with the clutch.

So I just got this response from a former Chevy dealer mechanic. It turns out this car has a very complicated computer controlled air conditioner

So when I was delivering organic fruit - I could not continue the job, primarily because no one here could repair the AC in the car! So I was hoping it was just the "actuator" which is something that is easily overlooked. When I asked another car owner about this - and he explained more about the AC system - then I realized no it's not the actuator (the relay switch to change from hot to cold air vents).

No - so then I, today and yesterday, "tested" the AC system - doing a few small tests - and I concluded - for real - it is the "fan clutch." This is the SAME part that we had replaced twice before - and neither times did it really "fix" the AC.

So then I had to figure out WHY would the "fan clutch" keep breaking - and why did replacing it not "fix" the problem?

So then I reread the repair notes from five years ago - when we had the fan clutch replaced (twice in a WEEK!!)

And I also read up on the forums where other owners of the same car discussed this same problem.

Then I encountered this zinger:

 You need the PCM update or the ticking noise will eventually come back and ruin the new clutch.

So then when I reread the repair notes - the "technicians cited a certain "Technical service bulletin" - stating it had been cancelled. Then they said - the HVAC had computer updates but they were "not sure it would help."

So this is a fine line between being either lazy or uninformed. They HAD to have read the bulletin - because I looked it up! It took me a while to track it down.

 no cold air from vents, a/c inoperative, blows warm air (reset hvac control module)

 So that's a direct quote from the technical service bulletin and since the mechanics stated that the HVAC needs updating - then they MUST have read the same bulletin that they cite. But since the bulletin was now "out of date" - then the mechanics could claim they were "not sure" it would "improve" the HVAC!!

Quite the slippery logic they imposed on the repair job!! I can understand being over worked and maybe not being sure HOW to do the computer update?

So I kept digging - "when" was it cancelled and why?

There was a later TSB for 2005-2008 models (07-01-39-007A-No cold air from vents, A/C inoperative, blows warm air (Sep 26, 2007)) but this was cancelled by TSB 07-01-39-007B (Dec 9, 2008). The original solution for this one was to reset the HVAC Control Module by removing and re-installing the HVAC control module fuse (in rear fuse block under driver’s side rear seat). The TSB cancellation notice said if problem occurs, diagnose using information in SI (GM Service Information, aka the service manual).

Wow - so the "cancellation" TOLD the mechanics to ignore the computer update - so THAT's why they did not do it! Amazing.

So basically without that update then the compressor gets too hot when the car is idling in hot weather - and it causes magnetic damage to the fan clutch - something along those lines. The computer fix is to activate the fan clutch when the car is idling.

Ok thanks again for the encouragement. So then I hot-wired the 30-87 relay - and I could hear no clicking. And when I replaced the horn relay into the 30-87 relay - no cold air. Yeah I hear what you're saying about the condenser still working but even when I'm driving - I don't get cold air (it's just the external temp air blowing in). So I found this other youtube comment from a former Chevy dealer mechanic! Here is what he said:

"What I work [When I worked] for Chevrolet, all of us there at that certain dealer they [that] replace those clutches did the update. We did that because we didn't want it to come back and I have to do it again because we didn't reprogram. It's a very simple thing to reprogram. They [meaning my dealer mechanics] did not do it either because they're lazy or they're uninformed about the problem with the clutch." 

 So then I rechecked the repair notes from the dealer - and they cite the 2008 bulletin that "cancelled" the previous bulletin calling for PCM update and "Not sure if update will improve the HVAC." haha. What? They KNEW the previous bulletin had called for the update!

well here was another forum comment:

"There was a later TSB for 2005-2008 models (07-01-39-007A-No cold air from vents, A/C inoperative, blows warm air (Sep 26, 2007)) but this was cancelled by TSB 07-01-39-007B (Dec 9, 2008). The original solution for this one was to reset the HVAC Control Module by removing and re-installing the HVAC control module fuse (in rear fuse block under driver’s side rear seat). The TSB cancellation notice said if problem occurs, diagnose using information in SI (GM Service Information, aka the service manual)." 

and someone else commented on the trailvoy forum: "You need the PCM update or the ticking noise will eventually come back and ruin the new clutch." I'm pretty sure because the dealer did not do the PCM update therefore the new GM OEM fan clutch just went bad again! Pretty amazing. I really think I solved the mystery. haha. It's not worth another $1K to get another fan clutch installed just to insist they do the PCM update - and who knows what they will actually do or not?

Yeah I can not trust mechanics anymore - the previous place we had the car at - I had to keep calling back to try to find out what was going on - and the "front desk" person just keep saying deceptive stuff - first claiming it was being worked on and then two days later saying the car had just been LOOKED at. haha. So I had to just bring it to the dealer - since the SEAL is a dealer part. But now the seal still leaks - so I can't believe they actually did any of the seal work. The pinion seal is not leaking but I think that stopped before also - after I painted it. haha. Yeah I think there's just a serious disconnect between the "service consultant" and the mechanics - the mechanic probably just didn't read the whole repair order - who knows? I took photos of the oil leaking out of the rear differential. We already paid for it. So the service consultant said they'd put on a new gasket cover. For something like $450 - we only get a seal, gasket and cover (that did not happen?). haha.

yeah I can't even sleep because of this. I realize mechanics are overworked and are cranking out repairs all day long, etc. but I guess I should have told them - it's NO RUSH - just please do the work. haha. All I can do is "TRUST" that they did the differential fluid replacements on front and back? It sucks - who knows what happened. They supposedly did the Transfer Case fluid replaced also. It's kind of a miracle the car still runs so far. I'm getting the Transmission pan "dropped" - and "cleaned out" (I will tell them) - and then fill back - hopefully 4 to 6 quarts - and the transmission filter replaced. We have never had the transmission filter replaced! Wow.