A/C compressor not engaging
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Freshman User
Joined: Feb 2007
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From: Detroit
A/C compressor not engaging
I have a 95 F-150, 300, whose A/C recently stopped working. The refridgerant level is fine, and the A/C clutch fuse is okay, the compressor just won't engage. Where do I start?
Posting Guru
Joined: Aug 2005
Posts: 1,036
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From: NE Ga
Jump the low side switch. Make sure you have at least 80psi on the system. If the clutch kicks on after jumpin the switch, either you don't have enough freon from a leak somewhere or the low side switch is bad. Or the wires to the switch are corroded.
Post Fiend
Joined: Oct 2003
Posts: 5,903
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From: MICHIGAN
Tap the compressor clutch with the engine running and the AC on. Use a chunk of wood or something. IF the clutch engages you may need to re-set the air gap on the clutch. .015 inch IIRC. Do you have 12 volts on the clutch connector? Even with a good fuse the wiring could be shot somewhere.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
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From: Lorain County, Ohio
How do you know the refrigerant level is fine? How did you check it?
If you checked it with a cheap AutoZone gauge and it read "good" with the compressor not running, you are way low on refrigerant. You need at least 45 psi for the cycling switch to engage the clutch. (The gauge needs to be read with the compressor running).
If there is less than 45psi static pressure in the system it will be contaminated with air and moisture, so you will need an accumulator in addition to fixing the leak, evacuation and recharging,
If you checked it with a cheap AutoZone gauge and it read "good" with the compressor not running, you are way low on refrigerant. You need at least 45 psi for the cycling switch to engage the clutch. (The gauge needs to be read with the compressor running).
If there is less than 45psi static pressure in the system it will be contaminated with air and moisture, so you will need an accumulator in addition to fixing the leak, evacuation and recharging,
Senior User
Joined: Apr 2007
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Originally Posted by Cuda_jim
Tap the compressor clutch with the engine running and the AC on. Use a chunk of wood or something. IF the clutch engages you may need to re-set the air gap on the clutch. .015 inch IIRC. Do you have 12 volts on the clutch connector? Even with a good fuse the wiring could be shot somewhere.
it stays engaged until i turn the switch off. How do i check the air gap?
Also whith the clutch engaged my ac still doesnt blow cold.( im looking at updating to 134-a though.
Junior User
Joined: Aug 2004
Posts: 54
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From: Delaware
You check the gap in between the clutch face and pully. (See pic below)
If you take off the 8mm bolt on the front of the clutch there might be shims (washers) under the clutch face. If so try removing one and see if that helps. This changes the gap in the clutch. Had it happen to my 97 150 and it has been working great now for two years.
You don't even have to take off the belt.
Here is a picture of the breakdown.....
Hope this helps
Ron
If you take off the 8mm bolt on the front of the clutch there might be shims (washers) under the clutch face. If so try removing one and see if that helps. This changes the gap in the clutch. Had it happen to my 97 150 and it has been working great now for two years.
You don't even have to take off the belt.
Here is a picture of the breakdown.....
Hope this helps
Ron
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