Squeeling when A/C is turned on high
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Senior User
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From: Nova Scotia, Canada
Squeeling when A/C is turned on high
When I start my 96 and turn the A/C to high and start to accelerate it squeels like mad. If I turn it down to normal A/C it's ok. I recovered the charge ( down almost 1/2lb but could not find any leaks) last year, put in a little oil and recharged the system...It was ok for the rest of the season. I tried a new clutch - didn't help. My A/C is nice and cold, down to 4*C leaving the dash but the squeeling on high drives me nuts....Any idea's?? I have another pump here from a 94 Mustang GT, looks to be the same so maybe I'll swap them and try that?
Fleet Mechanic
Joined: Feb 2006
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From: Lorain County, Ohio
Originally Posted by Manwith3fords
When I start my 96 and turn the A/C to high and start to accelerate it squeels like mad. If I turn it down to normal A/C it's ok. I recovered the charge ( down almost 1/2lb but could not find any leaks) last year, put in a little oil and recharged the system...It was ok for the rest of the season. I tried a new clutch - didn't help. My A/C is nice and cold, down to 4*C leaving the dash but the squeeling on high drives me nuts....Any idea's?? I have another pump here from a 94 Mustang GT, looks to be the same so maybe I'll swap them and try that?
What were the AC system pressures before you recovered the charge?
Posting Legend
Joined: Sep 2001
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A slipping serpentine belt is a ruined belt, it also ruins the pulleys. Check the Garage Forum FAQ for serpentine belt trouble repair, post #10:
https://www.ford-trucks.com/forums/9...ease-read.html
https://www.ford-trucks.com/forums/9...ease-read.html
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From: Nova Scotia, Canada
No, it's like metal on metal scrapping....Souns like a brake lathe when turning a rotor only much louder....Maybe the A/C clutch coil is too weak to hold in when the pump is on max A/C???....It's not a belt squeal - I can say that for sure.....Can't exactly remember the pressures as my truck uses a different system than Freightliner and the pressures are less on the Ford....I think they were around 30 and 150 if I remember right.
Fleet Mechanic
Joined: Feb 2006
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From: Lorain County, Ohio
Originally Posted by Manwith3fords
No, it's like metal on metal scrapping....Souns like a brake lathe when turning a rotor only much louder....Maybe the A/C clutch coil is too weak to hold in when the pump is on max A/C???....It's not a belt squeal - I can say that for sure.....Can't exactly remember the pressures as my truck uses a different system than Freightliner and the pressures are less on the Ford....I think they were around 30 and 150 if I remember right.
To figure it out, the system needs to be fully charged (or as close as you can get it) and you need to know the pressures when the clutch slips. It could be a weak clutch, high head pressure, failing compressor, air in the system, etc.
Either way, the clutch is going to need replaced, but you also need to find the root problem.
Question: Did you ever charge the system without pulling a deep vacuum first?
Last edited by lsrx101; May 27, 2007 at 08:02 AM.
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From: Nova Scotia, Canada
I did pull it down to 30" of vacuum before I put a full charge in. The new clutch didn't make a difference at all. I did get a good suggestion from another forum - I forgot to check my clutch gap. Do you know what it should be? If you turn the A/C to MAX, start to acclerate and bingo - screetching clutch is all you hear. If it was on the NORM setting it won't do it. We have a very good A/C guy at work, he looked at it with me and said my pressures were normal for the type of system. I'm still learning A/C - I do quite a bit of it but I'm no expert. It's a fixed orfice system isn't it in the F-series? The Mustang pump I have here has about 90,000K on it and it worked good when we stripped the A/C from my buddy's stang.
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Fleet Mechanic
Joined: Feb 2006
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From: Lorain County, Ohio
Thr clutch gap should be .025 or less, the narrower the better. I use a business card as a go/no go gauge. Usually a wide clutch gap will cause the clutch to disengage at random or fail to engage. I'm still curious as to what the head pressure is before the clutch starts to slip.
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