Intermittent A/C
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Junior User
Joined: Jan 2005
Posts: 60
Likes: 0
From: Huntsville, TX.
Intermittent A/C
I posted this in the HVAC section also...
<HR style="COLOR: #d1d1e1" SIZE=1><!-- / icon and title --><!-- message --><TABLE width="100%" border=0><TBODY><TR><TD vAlign=top>It just started to warm up enough to use the a/c with regualrity. I was on the road for about 3 hours the day before yesterday. My A/C was working fine for a while, then started blowing warmer than normal air. I turned it off for a few minutes, thinking low refrigerant might be the cause. It started working fine again, but only for a while. Then it became itermittent with cold then warm air.
I checked the refrigerant pressure today, and the guage read 35 psi.
I have a thermometer in the center vent. When the A/C works normally, it reads +/- 50 degrees. When it starts blowing warm, it will quiclky rise to +/- 90 degrees. When it blows warm, the center of the compressor pulley is not turning.
I have noticed no strange noises while driving lately that would give me a clue that something mechanical has failed (squealing, screeching, rubbing, rattling, etc).
Any ideas?
</TD></TR></TBODY></TABLE>
<HR style="COLOR: #d1d1e1" SIZE=1><!-- / icon and title --><!-- message --><TABLE width="100%" border=0><TBODY><TR><TD vAlign=top>It just started to warm up enough to use the a/c with regualrity. I was on the road for about 3 hours the day before yesterday. My A/C was working fine for a while, then started blowing warmer than normal air. I turned it off for a few minutes, thinking low refrigerant might be the cause. It started working fine again, but only for a while. Then it became itermittent with cold then warm air.
I checked the refrigerant pressure today, and the guage read 35 psi.
I have a thermometer in the center vent. When the A/C works normally, it reads +/- 50 degrees. When it starts blowing warm, it will quiclky rise to +/- 90 degrees. When it blows warm, the center of the compressor pulley is not turning.
I have noticed no strange noises while driving lately that would give me a clue that something mechanical has failed (squealing, screeching, rubbing, rattling, etc).
Any ideas?
</TD></TR></TBODY></TABLE>
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
These compressors need shimmed sometimes after a lot of miles. Like the coil is too weak to pull the clutch in or something. Sounds like what's happening to yours. Next time it's acting up, give the clutch a little love tap and see if it pulls in.
Post Fiend
Joined: Sep 2006
Posts: 5,584
Likes: 0
From: Millbrook Alabama
I am with Joe on this, the airgap between your clutch wheel, and pulley has probably exceeded .027. the optimal airgap between the clutchwheel and the pulley is .023 to .025. the compressor clutch rebuild kit is pretty inexpensive, so just go ahead and rebuild the thing.
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Post Fiend
Joined: Feb 2007
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From: Blairsville,Ga
Izzy is also right about clutch shims
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Thread Starter
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Junior User
Joined: Jan 2005
Posts: 60
Likes: 0
From: Huntsville, TX.
Roger that. I'll give it a try.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Some things I've posted about shimming in the past.
See Post #8 in this thread:
https://www.ford-trucks.com/forums/6...-question.html
Also, #10 in this one:
https://www.ford-trucks.com/forums/5...king-well.html
Especially #3 in this one:
https://www.ford-trucks.com/forums/5...-problems.html
Pop
See Post #8 in this thread:
https://www.ford-trucks.com/forums/6...-question.html
Also, #10 in this one:
https://www.ford-trucks.com/forums/5...king-well.html
Especially #3 in this one:
https://www.ford-trucks.com/forums/5...-problems.html
Pop
Post Fiend
Joined: Feb 2007
Posts: 7,191
Likes: 4
From: Blairsville,Ga
165-225 psi ,rule of thumb 2 times ambiant temp + 15 to 20%
Junior User
Joined: Feb 2004
Posts: 74
Likes: 0
I have a very similar problem on my early 99. The compressor seems to kick off when the engine is warm. Here are the weird details I have noticed. The A/C turns off when I slow down to a light. The RPM drops to about 800 the compressor switches off. The interesting part is that it will not come back on until I rev the engine to above 1500 RPM. If I am running highway speeds (1500 RPM or higher) the A/C will stay on without any problems.Pressures seem right both High and Low. The low pressure switch is working properly according to my LED experiment and now I am in the process of testing the high pressure switch. You guys seem to indicate it might be the Compressor spring or shimming. Any other ideas. Thanks
Post Fiend
Joined: Feb 2007
Posts: 7,191
Likes: 4
From: Blairsville,Ga
I have a very similar problem on my early 99. The compressor seems to kick off when the engine is warm. Here are the weird details I have noticed. The A/C turns off when I slow down to a light. The RPM drops to about 800 the compressor switches off. The interesting part is that it will not come back on until I rev the engine to above 1500 RPM. If I am running highway speeds (1500 RPM or higher) the A/C will stay on without any problems.Pressures seem right both High and Low. The low pressure switch is working properly according to my LED experiment and now I am in the process of testing the high pressure switch. You guys seem to indicate it might be the Compressor spring or shimming. Any other ideas. Thanks
Thread Starter
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Junior User
Joined: Jan 2005
Posts: 60
Likes: 0
From: Huntsville, TX.
Some things I've posted about shimming in the past.
See Post #8 in this thread:
https://www.ford-trucks.com/forums/6...-question.html
Also, #10 in this one:
https://www.ford-trucks.com/forums/5...king-well.html
Especially #3 in this one:
https://www.ford-trucks.com/forums/5...-problems.html
Pop
See Post #8 in this thread:
https://www.ford-trucks.com/forums/6...-question.html
Also, #10 in this one:
https://www.ford-trucks.com/forums/5...king-well.html
Especially #3 in this one:
https://www.ford-trucks.com/forums/5...-problems.html
Pop
Where do I measure the air gap?
