A/C Issues STILL ONGOING

[armyhockeynut]

I continue to have issues with the A/C unit in my 2004 Chevy Silverado 2500HD. This has been an ongoing issue for several years and numerous trips to the repair shop. Everytime, someone thinks they "figured it out", it works and then returns to the same old thing. First off, the issue is not that it needs to be "recharged" This is a common repsonse, but that has been check and rechecked and all in order. No leaks either. The basic problem is that the A/C will work fine as long as the truck is maintaining a decent RPM. If we hit heavy traffic or stop and go city traffic, the a/c gives out and never returns even if we get back up to a prolonged period of normal speed. When we are towing the camper it is worse. Friday and yesterday the A/C would not work at all. As we drove I had a volt meter in the cigarette lighter and it was reading around 13.87 when I would turn on the a/c it would only drop to 13.77. Aa most know, yesterday was not a day to be without A/C here in Virgina.
This morning, I drove the truck to the train station and the volt reading was 14.45 and the a/c was blowing ice cold. In thwthe afternoon the a/c blows cold on the ride home too. So I am at a loss.
My gut says that the A/C is not getting the required power it needs to run properly.

Input please!

[Thunderbolt]

I have similar issues with my 2003. Back in 2005 the AC quit working so I took it to the dealer I bought it from. New orifice and new compressor were installed. I picked up the truck and after about 10 miles it started acting up. Pulled in the driveway and heard load hissing (not the hissing of the pressures equalizing when you shut the engine off) and when I open the hood it is purging out the high pressure relief. Back to the dealer the next day. Not sure what they did that time, but it worked for about 3 days.
Took it to a different dealer and another new compressor and system flush as well as new orifice tube. I said I wanted a new condensor as well, but GM denied it. Truck had worked great since then until last summer and it would sometimes only blow cool air and not cold for awhile and then start blowing cold again. The other day it wouldn't work at all and after moving the temp from cold to hot and back it worked. That I think was a blend door stuck since the truck has been sitting for some time.

Sorry for the long post. I just wanted to give all the details of what I went through which appears similar to the OP's issues. I am curious to see what he finds out.

[wnjj]

Gdetrailer wrote:
This is a common problem and often misdiagnosed as low coolant.

The symptoms you describe are typical of a worn A/C clutch (NOT FAN CLUTCH).

Someone else had mentioned this but I will elaborate a little on this..

Simply put, the A/C clutch works by using a electro magnet to create a magnetic field. This field "pulls" or draws the clutch together. When this happens the compressor shaft turns with the pulley.

In order to reliably pull or draw the clutch together there is a MAX distance allowed. Typically the clutch material wears down to the point the gap enlarges past the point of max distance.

Not all is lost, the clutch gap MAY be restorable. There may be a set of "shims" that can be removed.

Worst case is the clutch simply needs replaced...

Please take a look at the link below, although it is about repairing a Ford A/C clutch you will most likely find this info of great help..

SPRINGERPOP A/C AIR GAP REPAIR

First thing to do is MEASURE the AIR GAP of the clutch instead of reaching for a can of freon...

If air gap is correct then you need to trouble shoot the pressure switches, there can be several of these, one placed on the high pressure line and one on the low pressure line.

Additionally a clog in the system can cause issues but that SHOULD HAVE BEEN DETECTED if the A/C repairman used a set of gauges..

I had a gap problem on my Dakota (Sanden compressor). It would work great some times then not at all. When I watched under the hood when the AC was engaged, the clutch would shutter slightly but not engage and turn. With the AC on I bumped the end of the clutch with a broom handle and it grabbed and stuck. When I looked into it further I found a severely worn clutch (which I think was from excessive cycling on defrost during the winter when it was low on charge). I was able to pull a shim washer out and close the gap back down. It ran perfectly for many years after that.

[_40Fan]

Low voltage will kill a compressor clutch in a short time. I'd make sure they check the voltage going into the compressor clutch right at the plug. I have wired in many relays that supply power to the clutch directly from the battery.

[1oldtruck]

I had a similar problem on a 2001 GMC. They found a filter in the line just in front of the evaporator was clogged. AC worked until the line froze up. It would work again later after thawing out. Usually a few minutes with the engine off. New filter and a recharge solved the problem.

[Tachdriver]

I had a problem with my 1996 C1500, the compressor was intermittent in engaging the clutch, was the relay. Relay had a bent pin and overheating the relay, which was due to my negligence.

May want to check for a bad relay

[PAThwacker]

I just replaced the compressor on our 2004 Passat wagon, next up the 2004 burb. 10Year old vehicle plague.

[chracatoa]

I had a similar problem with my Sequoia (related to what Gdetrailer said). I took it to the dealer several times (actually since the first day I had the car) and they would only add coolant while saying everything was fine, it was all in my head. After 1 year and a half the AC died completely in a very hot day and they had to replace the clutch. Luckily it was still in the warranty.

[Gdetrailer]

This is a common problem and often misdiagnosed as low coolant.

The symptoms you describe are typical of a worn A/C clutch (NOT FAN CLUTCH).

Someone else had mentioned this but I will elaborate a little on this..

Simply put, the A/C clutch works by using a electro magnet to create a magnetic field. This field "pulls" or draws the clutch together. When this happens the compressor shaft turns with the pulley.

In order to reliably pull or draw the clutch together there is a MAX distance allowed. Typically the clutch material wears down to the point the gap enlarges past the point of max distance.

Not all is lost, the clutch gap MAY be restorable. There may be a set of "shims" that can be removed.

Worst case is the clutch simply needs replaced...

Please take a look at the link below, although it is about repairing a Ford A/C clutch you will most likely find this info of great help..

SPRINGERPOP A/C AIR GAP REPAIR

First thing to do is MEASURE the AIR GAP of the clutch instead of reaching for a can of freon...

If air gap is correct then you need to trouble shoot the pressure switches, there can be several of these, one placed on the high pressure line and one on the low pressure line.

Additionally a clog in the system can cause issues but that SHOULD HAVE BEEN DETECTED if the A/C repairman used a set of gauges..

[MARK_VANDERBENT]

I had a problem similar on my suburban ended up having bad electrical connection on the dryer can plug on side pressed wires into harness and connection was good again. Could be a loose wire issue that comes and goes with vibration and high heat.

[transamz9]

armyhockeynut wrote:
Thank You everyone for the feedback. As I said this is has been an ongoing annoyance over many years. The truck has been to 2 seperate chevy dealers, 2 firestone service centers several times, a repair shop that specializes in trucks, and from all the invoices it appears that every part of the a/c unit has been replaced. The last mechanic to work on it, swore he had it fixed and claimed that he drove it out and thru the city and it worked fine. BS! I appreciate the comments. Will be discussing this with the mechanics at a new shop in hopes that we can come to final diagnosis, repair.

The problem with the places that you mention is that every one of then use a machine to do the service. The Techs are trained on the machine and all they do is punch in what vehicle it is hooked to and the rest is done by the machine. They have no clue how to read the gauges and if there is a problem somewhere in the system the machine won't tell them. Try and find a garage where the A/C tech actually hooks a set of gauges to it and reads them. There is certain readings he will look for and times these readings are happening. A lot has to do with temperature and humidity. Good luck and follow up with what you come up with. I bet it's something simple that all the other techs are overlooking because they don't know what to look for.;)

BTW, running down the road your system should be blowing around 33-38 degree air once the cab cools out and you are running on Max mode.

[rickgu]

My 03 had the same symptoms for years and the compressor finally went out. Ever since I've had my truck I've been able to hear the compressor run and thought it was normal but now that I have the new one in I can't hear it run at all. I can barely hear it engage and it's worked perfectly since. My mechanic also replace my orifice and dryer too. But no more sitting in traffic with the AC blowing hot or it shutting off at random.

[armyhockeynut]

Thank You everyone for the feedback. As I said this is has been an ongoing annoyance over many years. The truck has been to 2 seperate chevy dealers, 2 firestone service centers several times, a repair shop that specializes in trucks, and from all the invoices it appears that every part of the a/c unit has been replaced. The last mechanic to work on it, swore he had it fixed and claimed that he drove it out and thru the city and it worked fine. BS! I appreciate the comments. Will be discussing this with the mechanics at a new shop in hopes that we can come to final diagnosis, repair.

[jmckelvy]

Engineer9860 wrote:
Check the air gap between the A/C compressor clutch, and A/C compressor pulley. If the gap is at the maximum limit a low voltage may not be creating enough of a magnetic field for the electromagnetic coil to pull the clutch in.

X2.

I have a 2000 Jeep Cherokee which had similar symptoms. No obviously bad anything. Turns out the rubber bumper stuff in the AC clutch mechanism had become hard and brittle with age. Worked fine when cool but when everything heated up the clutch would not pull in enough to engage the compressor. I simply removed some of the rubber and it has been working fine ever since.

[transamz9]

I know this is bad to say but you need to find another A/C man. No one is going to be able to fix this over the internet without seeing what is actually happening. I would need to see what the manifolds are reading and watch what they are doing.

Couple questions for you:

Has the system ever been opened?
Has the compressor been replaced?
Is the condenser clean?

There could be a number of things that could be causing this but your voltage is fine.
It could be as simple as the $2.00 orifice. You could have a blend door problem in the dash. Could have too much freon. It could have too little freon and freezing up. It could be a weak compressor. Compressors can work fine at low RPM and then not work at higher RPM.

Like I said, without having the manifold gauges hooked up in front of me it could be a number of things. I had a Dodge dealer warranty a compressor 4 times in two months and it ended up being the orifice tube. I had to do the work myself to get it right. PM me if you want to talk about what's going on with your truck (what's been done and what they are telling you) and we can seen if we can get you cooling. A/C systems are not hard to work on it's just everything has to work properly or it won't work at all. The hardest part is figuring out what's not doing it's part. 😉