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A/C belt noises progressed to hissing and now no A/C


JimiMc

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Hello, I've got an issue with my a/c on my 2001 GMC Sierra.

 

Last summer, 2013, I lost my original a/c belt. After replacing the belt, I had a strange periodic noise that sounded like the belt was slipping or flapping while first starting out it 1st gear to 2nd gear. It would then sometime make a little noise at speed, but not always. I figured it was just a crappy aftermarket belt that slipped and continued to drive with it. That replacement belt lasted just about a year. So I replaced it again. The new belt made the exact same noise.

 

After installing the new belt and having to deal with the noise again, I decided to leave it and planned on replacing it again next year if and when it broke. The A/C worked fine.

 

Just the other day, (about a month after replacing the belt) I was driving and could hear an odd noise while driving. I lowered my window and could not hear it with the wind noise, so I figured it was an outside noise not related to my truck. I arrived at my destination about 2 minutes later. While walking into the store, I could hear a hissing noise coming from the front end. It sounded as if a tire was leaking from a nail or something. But it was not the tires. I raised the hood and could hear it coming from down near the compressor. The was a very noxious odor rising up from there. I started the engine and could see vapor or smoke getting blown around by the fan. It eventually stopped and now my A/C does not blow cold any longer.

 

After driving the truck back home, I crawled around trying to isolate the trouble so I could order whatever part I needed. I detected no obvious spots on the lines, and the pully/clutch on the compressor spins freely. I then noticed a wire haging loose near the rear of the compressor. A purple plug was attached that looked as if it had melted or been chewed up or something. No idea how that could have occurred. After searching the net, it appears to be the high pressure switch. I could buy a new one, but I don't think it would be able to seat properly due to the remnants of the old one still stuck in the compressor.

 

Could the noises have been the compressor going bad, then eventually blowing the high pressure switch out of it? If so, would it leak out? Kind of stuck on what to do. Any help would be appreciated.

 

Jimi

 

 

 

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Thank you both for your input. I guess it's time to do some work.

 

Interestingly enough, I've always had an issue with the a/c losing it's cold while sitting idle at stop lights or just sitting still since I bought it new. I took it to a dealer when it was a year old and still under warranty when the a/c stopped working completely. I guess I didn't care to remember what it was, because there's no memory of it. But the same issue while at low RPM has been there before that repair and after. I just kind of got used to it. I'll try contacting the dealer and see if they still have a record of it.

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Thank you both for your input. I guess it's time to do some work.

 

Interestingly enough, I've always had an issue with the a/c losing it's cold while sitting idle at stop lights or just sitting still since I bought it new. I took it to a dealer when it was a year old and still under warranty when the a/c stopped working completely. I guess I didn't care to remember what it was, because there's no memory of it. But the same issue while at low RPM has been there before that repair and after. I just kind of got used to it. I'll try contacting the dealer and see if they still have a record of it.

 

Not uncommon for the air to be warmer at idle after a few minutes. It is usually due to reduced airflow over condenser. Before EFI you could raise idle speed a bit to reduce the effect in traffic. When I took the a/c courses many, many, many years ago, they taught to properly test a/c condition the idle speed should be raised to 2,000rpm, and engine fan must be working properly(ie clutch fan should engage as high side pressure increased).

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the slapping noise you are hearing is the idler. The idler is making noise because the compressor is failing. Replace the compressor and idler and flush the system. Same thing happened to our Tahoe. Compressors are fairly reasonable, get a drier while you are doing it and replace any suspect hoses

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Also replace the fixed orifice tube. Make sure that air flow through the condenser is not being restricted by things like a bug screen, or blocked fins on the condenser itself. Not enough air flow will cause the high side pressure to rise to the value the high side safety blows out.

 

I once had a customer come in with her year old Fairmont complaining of loud squealing and smoke from under hood while idling at stop lights. She also said she had the fan belt replaced twice yesterday. Her issue was the aftermarket a/c that was installed a month prior did not include a replacement engine driven fan. Stock fan was a two bladed "propeller" looking item. Air flow at idle was so low that the high side pressure would get so high it would stop the compressor pulley from turning, burning the belt off if left long enough at idle. As soon as the car started moving, air flow was sufficient to prevent the build up of pressure. Stupid part was that when the a/c was added, the shop called here outside to see the job they did installing it. She told me that the shop was running a garden hose over the condenser while idling, and told her that it was normal for a mechanic to run cold water over the condenser while running car in shop due to not enough air through the rad. Never dawned on her to relate that to the belt issue a while later since she did not use the a/c much, if at all in the first month due to outside temp.

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Revive an old post...

 

I went through the cold months and finally got around to replacing my idler, compressor, and drier. After taking my truck to a shop to charge the system, I found out a hose crimp was bad too. Replaced it then recharged again. :nonod:

 

Strange thing... A/C is working again, but my sitting still and idle issue of the temp getting warm issue is now gone. I can sit and idle and stay icy. But once I get up to highway speed the temp seems to get less cool. (Completey opposite than before.) Not horrible warm, just not as cool.

 

What would cause the temperature change to warmer at speed? Could it be that missing brittle insulation blanket I did not replace on the drier?

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