Air Conditioner Issues

ChicharronR

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Haven't read all of the pages of responses, but mine has/had the issue until I figured out what the culprit was. I think I left the AC on while on the track, so, my AC switch seems to have bouts of confusion. If it blows hot, I get the car up over 4k rpm...bring it back down....blows cold again. It works like clockwork.

Sucks...but, my mistake (I think)

 

galaxy

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My whining is getting pretty constant, but…only when the AC is on. No AC, no noise. And works just fine (cold air).

Does this sound like a clutch issue some have mentioned? Where can you get just the clutch? Easy enough to replace?

*edit— holy shit, a clutch is just as much as the whole compressor.
 

rick81721

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My whining is getting pretty constant, but…only when the AC is on. No AC, no noise. And works just fine (cold air).

Does this sound like a clutch issue some have mentioned? Where can you get just the clutch? Easy enough to replace?

*edit— holy shit, a clutch is just as much as the whole compressor.
Same symptoms as mine. They had to replace everything.
 

DCShelby

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Yes. In my first 18 I had to get new compressor at 20k miles. In fact, I remember that I hadn’t used it all winter, one spring day it was hot in the garage and I turned it on…got that burnt clutch smell and poof it was gone. So in my second 350, I made sure to turn it in to max a few times in the winter to keep the compressor clutch lubricated
 


DCShelby

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If they have to replace the evaporator then the whole dash comes out……if your out of warranty….that’s a big biill
 

galaxy

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Not out of warranty, but part of me, most of me, wishes I was. Otherwise I’d never in a million years let them do this job. It’s killing me to take it in as it is. Sitting here contemplating as we speak paying out of pocket for a compressor so that I can do it myself.
 

Sletcher

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Not out of warranty, but part of me, most of me, wishes I was. Otherwise I’d never in a million years let them do this job. It’s killing me to take it in as it is. Sitting here contemplating as we speak paying out of pocket for a compressor so that I can do it myself.
I did this.

I ordered a new compressor and all other required items fromRockAuto and did it myself. I used a local performance shop to evacuate the system then I used my own vacuum pump to purge and charge the system after. I know it’s done right. High revs have a cost I guess. Mine is a 2020 with 14k miles. Had it more than two years and still love it.
 

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I turn mine off when I’m really getting into the high revs on a backroad on a hot day. I just lower the window. Then on the way home doing a cruise at 5th gear cruise 75 or 80 I’ll turn it on.
 

NoXiDe

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My whining is getting pretty constant, but…only when the AC is on. No AC, no noise. And works just fine (cold air).

Does this sound like a clutch issue some have mentioned? Where can you get just the clutch? Easy enough to replace?

*edit— holy shit, a clutch is just as much as the whole compressor.
Just pretend you got the AC Delete except for your carrying the extra weight.
 

galaxy

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I did this.

I ordered a new compressor and all other required items fromRockAuto and did it myself. I used a local performance shop to evacuate the system then I used my own vacuum pump to purge and charge the system after. I know it’s done right. High revs have a cost I guess. Mine is a 2020 with 14k miles. Had it more than two years and still love it.
Dude...that's exactly what I've done on other cars and soooo tempted to do it on this one. What "other parts" did you get?

I'm probably gonna take it in for the troubleshooting for that second opinion that it's just the compressor. Right now I'm treating it like it's herpes and hoping ignoring it will make it go away...but alas, I know that won't work, LOL.
 

Sletcher

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Dude...that's exactly what I've done on other cars and soooo tempted to do it on this one. What "other parts" did you get?

I'm probably gonna take it in for the troubleshooting for that second opinion that it's just the compressor. Right now I'm treating it like it's herpes and hoping ignoring it will make it go away...but alas, I know that won't work, LOL.
I felt it was important to replace before something failed and sent FOD through the system.
-Motorcraft Compressor from RockAuto $350
-Compressor bolts from Blue Springs Ford
-AC compressor o-ring and gasket.
-AC belt, because I cut the old one off.
-134a
-The “Essentials” thread that is pinned at the top of the 350 forum has good information.

I gave this a 5/10 for difficulty, but I’ve changed AC components before and had things like a vacuum pump on hand.
 

HoosierDaddy

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If the system is low on Freon, the compressor won’t kick on via the A/C pressure switch in the engine bay
@Cobra Jet

If I turn on AC, my compressor clutch will engage but just for a few revolutions. Can I assume that fits your scenario because of reaction time with the sensor? Best I can tell observing with hood open, clutch will not re-engage again at least for the several minutes I watched. And it will NOT re-engage if I turn AC off then back on again. It will only engage for a few revolutions the FIRST time AC is turned on until next time the car is driven.

What's got me confused is my issue has come and gone for days or weeks at a time. If the root cause is low pressure and the system can't make more :wink: why would the sensor decide pressure okay for days on end and not for other days on end? Flakey sensor? Other environmental conditions affect pressure?

When working, it works great but maybe normal to work great as long as pressure is enough to satisfy sensor?
 
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Cobra Jet

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@Cobra Jet

If I turn on AC, my compressor clutch will engage but just for a few revolutions. Can I assume that fits your scenario because of reaction time with the sensor? Best I can tell observing with hood open, clutch will not re-engage again at least for the several minutes I watched. And it will NOT re-engage if I turn AC off then back on again. It will only engage for a few revolutions the FIRST time AC is turned on until next time the car is driven.

What's got me confused is my issue has come and gone for days or weeks at a time. If the root cause is low pressure and the system can't make more :wink: why would the sensor decide pressure okay for days on end and not for other days on end? Flakey sensor? Other environmental conditions affect pressure?

When working, it works great but maybe normal to work great as long as pressure is enough to satisfy sensor?
@HoosierDaddy
Usually the quick off/on cycle like that is associated with:
- Low freon
- bad A/C pressure switch

If you have a way of measuring the freon level, I'd do that first. If you're within spec for the Freon level, proceed to the pressure switch.

The pressure switch is usually located back by the firewall on or near a cylindrical A/C unit (accumulator?). It should have a 2-pin connector going to it and the switch itself is usually screwed on to the top of the unit via a schrader valve type of fitting.

If the A/C pressure switch is totally in-op, loose, or unplugged, the clutch won't engage when A/C OR defroster settings are turned on. If the compressor clutch still tries to recirculate when turning on A/C or Defroster setting, it's usually not the A/C pressure switch. It's either a failing compressor or clutch/field coil or breach in the system and low on refrigerant.

Usually to test for A/C pressure switch failure, pull the connector off the top of the switch, jumper the harness connector and if the clutch engages, it was the switch. Now granted if refrigerant is low, a functional A/C pressure switch will still kick the compressor clutch on, but it will keep cycling quickly on/off, on/off etc and won't maintain a constant "on". That's when you know the system is low on refrigerant OR there's an issue with the clutchcoil.

I would also probe the connector on the harness to the pressure switch just to make sure there's no issue with the connector or harness.

Now if that tests out, then move on to the A/C clutch/field coil.

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This older post I had on here has a lot of info about the clutch/field coil and R&R of it:

This thread was from another M6G Member where the failure turned out to be the A/C field coil/clutch head:
https://www.mustang6g.com/forums/threads/what-is-this-passenger-side-lower-main-pulley-ac.121072/

This thread has the info from the Ford shop manual for how to remove the clutch assembly/field coil:
https://www.mustang6g.com/forums/th...tentially-a-c-compressor.129712/#post-2686995

There is also this thread which discusses how to remove the A/C stretch belt (and an available Lisle tool to do it too):
https://www.mustang6g.com/forums/threads/ac-stretch-belt-help-please.175709/#post-3554880
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Start systematically with the easiest diagnosis/checking for possible issues and migrate to the more difficult (or costly) diagnosis when determining any failure points on any vehicle.

If the vehicle is low on Freon, then next step at that point would be to find the leak using die in the system OR you can use a black light in the engine bay. Using a black light, hover over all A/C lines and junctures (fittings) along those lines to see if any refrigerant has seeped out through the fittings (shraders) or possible bad sealing o-rings or worst case major leaking at compressor, A/C condenser, or evaporator core.

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I know that's a lot to digest, but hopefully something above is helpful.
 

 
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