AC Clutch?
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5 Year Member
Joined: Jul 2013
Posts: 129
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AC Clutch?
I have a 2007 FX4 5.4 I'm trying to figure out my AC failure. History: It was working a couple of years ago and very gradually (a few months) became less cold until it you couldn't tell if it was on or not. I figured it was a leak, took it to a shop and they recharged it and said they could not find anything else wrong or the source of the leak. I had cold air again for the rest of last summer. Now it is back to not working. I bought a refill kit with a gauge. I know they are not the most accurate but the gauge indicates 👉very solid pressure. I did not add any refrigerant, only used the gauge. My next guess is the clutch. I tested the connector to the compressor and it is getting good voltage that corresponds to the switch being turned on/off. The clutch does NOT turn/engage irrespective of anything. So my question is, how do these clutches fail and how are they actuated? What is the mechanism? I can see the friction surface has not made contact with its mating surface because of the lack of recent wear(light staining visible). Other than that I can't see anything obviously wrong with it off the truck or installed. I'm trying to understand so I can zero in on the problem rather than throw parts at it. Thanks for any help here.
Senior Member
Joined: Jan 2020
Posts: 4,327
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From: utah
I have a 2007 FX4 5.4 I'm trying to figure out my AC failure. History: It was working a couple of years ago and very gradually (a few months) became less cold until it you couldn't tell if it was on or not. I figured it was a leak, took it to a shop and they recharged it and said they could not find anything else wrong or the source of the leak. I had cold air again for the rest of last summer. Now it is back to not working. I bought a refill kit with a gauge. I know they are not the most accurate but the gauge indicates 👉very solid pressure. I did not add any refrigerant, only used the gauge. My next guess is the clutch. I tested the connector to the compressor and it is getting good voltage that corresponds to the switch being turned on/off. The clutch does NOT turn/engage irrespective of anything. So my question is, how do these clutches fail and how are they actuated? What is the mechanism? I can see the friction surface has not made contact with its mating surface because of the lack of recent wear(light staining visible). Other than that I can't see anything obviously wrong with it off the truck or installed. I'm trying to understand so I can zero in on the problem rather than throw parts at it. Thanks for any help here.
5 Year Member
Joined: May 2019
Posts: 3,751
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Very common problem.
Clutches wear out over time causing the gap to increase. Eventually they either slip, become intermittent or fail to engage at all.
Use a feeler gauge to measure the clutch gap. IIRC, gap should be between around .15-.030". Once they exceed .040, the above symptoms begin.
If excessive, remove any shims if present. to bring the gap back into operating range. Worst case, replace the clutch hub and ship it to spec.
Clutches wear out over time causing the gap to increase. Eventually they either slip, become intermittent or fail to engage at all.
Use a feeler gauge to measure the clutch gap. IIRC, gap should be between around .15-.030". Once they exceed .040, the above symptoms begin.
If excessive, remove any shims if present. to bring the gap back into operating range. Worst case, replace the clutch hub and ship it to spec.
