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Discussion Starter · #1 ·
Ok, so the other day it was rainy and my windows were fogged and i hit the defrost..but that didnt really defrost anything that i was expecting. i figured it was just some really bad foggy windows...whatever... then it was hot out..so i went to kick on the ac (i got the truck in winter and didnt check the a/c...so i'm retarded :doh0715: ..) Well the ac just blows outside temp air. I get under the hood and notice the clutch is not engaging on the compressor..doesnt even try. I thought i'd check the refridgerant level (it was previously converted to 134a by i assume the previous owner) and the level looked fine (about 25 psi on the low side).

is there a test procedure for the cycling switch etc? i cant find one anywhere. Also..can i just apply voltage (12) to the clutch to see if it actually works?

I know i either have a problem in the clutch, the pressure switch, or the controlls inside the car...i just cant find any wiring diagrams or test procedures for any of this... any help greatly appreciated!

oh, and i read every article with a/c or clutch in it...i feel well versed in on board air!
 

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You can jumper the pressure switch connector. Just unplug it and jumper it. If the clutch engages, then you know the wiring works.
 

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Discussion Starter · #3 ·
sewiv said:
You can jumper the pressure switch connector. Just unplug it and jumper it. If the clutch engages, then you know the wiring works.
awesome.. i was just checking... i think i'll do that at lunch since i drove the truck today..

anyway to test the pressure switch?
 

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well, if you actually have Freon in the system, and jumpering the connector turns on the clutch......
 

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just go to your local auto parts store and get a new A/C pressure switch - it's only a $7-$10 part. Just unplug the connector going to it, then unscrew the old one with your hand. When you go to unscrew it it will make a slight "air burst", nothing to worry about as it seals up immediately. Take your new A/C pressure switch and screw it back on by hand and plug the connector back in... your A/C should work now.

I had this happen on a few Mustangs (including my 94 Cobra) - one day the air is ice cold, then the following day the air was luke warm... changed out the inexpensive pressure switch in a few seconds and I had instant cold A/C again.
 

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Discussion Starter · #6 ·
Cobra Jet said:
just go to your local auto parts store and get a new A/C pressure switch - it's only a $7-$10 part. Just unplug the connector going to it, then unscrew the old one with your hand. When you go to unscrew it it will make a slight "air burst", nothing to worry about as it seals up immediately. Take your new A/C pressure switch and screw it back on by hand and plug the connector back in... your A/C should work now.

I had this happen on a few Mustangs (including my 94 Cobra) - one day the air is ice cold, then the following day the air was luke warm... changed out the inexpensive pressure switch in a few seconds and I had instant cold A/C again.
looks like its $14 here...still not too bad. I'll jumper it to see if the clutch engages, if it does i'll just replace that switch....convieniently enough i can see the parts store from my office....
 

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Discussion Starter · #7 ·
Ok i jumped the switch and the clutch engaged..in fact ac got nice and cold....so i'll get the new switch in at lunch
 

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Discussion Starter · #8 ·
alright..that was a fun "work on the bronco" lunch. I had the switch jumpered and the clutch engaged. I hooked it back up and nothing. so i replaced the switch. Now it will engage/disengage every couple of seconds. i know i saw a thread about that on here, so i'm gonna go back and find it. after the compressor ran i went from 25psi to 0. I had a half can of 134 and put that in, pressure did not change. So now i either have a leak or its just completly empty (hence a leak). I'll have someplace to a leak check for me and if it checks out, i'll fill it up.
 

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Yeah, I'd guess you have a leak. Don't run your compressor for more than a little bit jumpered like that. You have a pressure switch for a reason, to keep you from burning up your compressor.

You may need to jumper it while adding coolant or oil or A/C stop-leak, of course.
 

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Discussion Starter · #10 ·
i disconnected the jumper, just ran the compressor for a few minutes and turned the ac on and off to make sure the switches in the truck were working. now however it is turning on and off after i put just half a can in there. I'm gonna have it flushed out and vac checked to see if theres any leaks.
 

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Discussion Starter · #11 ·
Thanks steve. so i need to be reading 27-28 on the low side. Like i said i'll flush it, vac it and then fill it with a little dye to see if i've got leaks.

the old switch looked like ass and the o ring was dry rotted, so i wont cry tobad over wasting that $14...i should probably take everything apart and replace any other o rings etc while i'm at it.
 

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Discussion Starter · #12 ·
Ok, no leaks. No gunk... it was just completly empty except for the 1/2 can i put in it initially. Its full now and ac is cold. It was charged last night and is still charged properly so its holding. I'll still probably take it apart and really give it a going over when i have some time.
 

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any photos of this switch?
 
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