A/C Clutch Will not Engage 2010 Mustang 4.0

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kyleivy2003
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A/C Clutch Will not Engage 2010 Mustang 4.0

Post by kyleivy2003 »

Hello, my vehicle is a 2010 4.0l v6 mustang, and I have had this specific issue about a year ago, however it turned out to be a bad pcm (which caused a number of issues) that was giving a bad ground, keeping the clutch from engaging. After fixing that issue, my ac has worked great since, granted blowing a little weaker than it should be. However, I started my car tonight and my ac was not blowing cold air, and then I realized that my ac clutch simply wasn't engaging anymore. I checked the fuse, the pcm is relatively new still, and the belt is good that's running along the pulley for the clutch. And while disengaged the clutch rotates fine with my hand, so It does not seem to be seized up. Any Ideas? Anything helps! Thank y'all.
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JohnHere
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by JohnHere »

I'm guessing that it's low on refrigerant, which would prevent the compressor from engaging. Have you connected a Manifold Gauge Set to check the static pressures?
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kyleivy2003
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by kyleivy2003 »

Sorry for the delayed reply, I checked it out and it turns out that for some reason the pressure was quite high. I am unsure what would cause this as it was carefully put under a vacuum and drained and recharged to "spec". I will check again tonight! Thank you I will keep updates coming!
tbirdtbird
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by tbirdtbird »

OK, as you continue to post, please provide the following...
Lo side psi
hi side psi
(Both of those using a manifold gauge set, the little plastic gauges that come with the cans of 134 + sealer at the parts store don't cut it. Also NEVER use one of those cans you will destroy your system. BTW has sealer EVER been used?)
Those pressures should be at 1500-1800 RPM
max fan
max cooling
doors open (you want a full load test)
Ambient temp

Stating "too high" or "too low" does not help us help you.

If you cannot get the comp to engage, give us whatever readings you can with the comp off. At that point the RPM is irrelevant. Also need ambient. Always post ambient.

Right now, from this distance, it looks as though it was not charged properly ( a common problem) and you will end up getting it evacuated and recharged to the correct amount based on the under hood sticker, BY WEIGHT not by guessing small cans. But let's see if you can give us some numbers.
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JohnHere
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by JohnHere »

Another problem that surfaces frequently on this Forum is the clutch gap—that is, a feeler-gauge measurement of the space between the clutch's drive and driven plates. For most vehicles, it should be ~0.020" or the thickness of a business card. If the gap is too wide, the clutch probably won't engage.

Reach in and measure the gap with a flat-blade feeler gauge, if you can, without removing the compressor (engine and A/C off). If the gap is too wide, you'll need to remove the bolt or nut in the center of the clutch, pull off the driven plate, and remove a shim to reduce the gap.
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Cusser
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by Cusser »

JohnHere wrote: Wed Oct 05, 2022 10:55 am Another problem that surfaces frequently on this Forum is the clutch gap—that is, a feeler-gauge measurement of the space between the clutch's drive and driven plates. For most vehicles, it should be ~0.020" or the thickness of a business card. If the gap is too wide, the clutch probably won't engage.

Reach in and measure the gap with a flat-blade feeler gauge, if you can, without removing the compressor (engine and A/C off). If the gap is too wide, you'll need to remove the bolt or nut in the center of the clutch, pull off the driven plate, and remove a shim to reduce the gap.
Yep, I fixed my own AC compressor slipping clutch (excessive gap) on my 1998 Frontier in 2019 by removing a shim; I didn't even need to take the AC belt off to do this. And it's still working fine to this day...
kyleivy2003
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by kyleivy2003 »

It turns out there was a really big obstruction in my orifice tube. After replacing and having the system evacuated and recharged it seems to be working quite well now! Thank you all for your help and Ideas! I apologize for not giving readings off of a manifold gauge set, I will be more specific in the future! :D
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JohnHere
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Re: A/C Clutch Will not Engage 2010 Mustang 4.0

Post by JohnHere »

Pressures definitely would have helped, but I'm glad you found the problem.

An obstruction at the OT would cause an abnormally low, low-side pressure or even cause the low side to pull into a vacuum, indicating a probable blockage at the metering device.
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