NEED HELP Air Con Compressor Not Cycling

therealsethallen

Original poster
Member
Sep 20, 2015
501
Western Mass.
This is a follow up to my A/C Acting strange at idle thread (See: Idle Hunting While Using Air Conditioning)

Today, I went into the store to grab a Keno ticket and a harass my friend that works there, I came out, got into my truck, turned the A/C on and it pissed out hot air. So I popped the hood, cranked it up and the compressor wasn't doing a thing. I pulled out my owners manual, checked all the fuses (Front and Rear) related to the HVAC system or A/C and they all seemed to work. I replaced relay #44 with the horn relay, tapped the horn and it worked. So the relay is fine. It's been humid as a son of a bitch here all week and I'm not in the mood to deal with this right now.

I did remove the low pressure switch, and I plan to replace it as it's a cheap part and easy to eliminate, could it be the high side switch?

I honestly think it's the compressor unless someone gives me another idea my tired brain hasn't thought up. Now I have the one from my junkyard motor, but I don't remember what one they used. The engine did come from a TBEXT with rear air, so are they even compatible?
 

therealsethallen

Original poster
Member
Sep 20, 2015
501
Western Mass.
I plugged my little thingy onto the little thingy. (I know, such science). Pressures are fine. It's 1am here, I start orientation for my new job at 8:30am and I'm sitting here bitching about A/C because it's supposed to be 97 tomorrow and I have to park the Saablazer in a sunny lot all day.

Silly question, would the connector on the back of the compressor not being plugged in have any significant effect on the operation of the compressor?

Because I unclipped it and put it back in, and the compressor kicked on right when I fired her up.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Yes
 

DAlastDON

Member
Apr 6, 2014
5,550
Kentucky
I plugged my little thingy onto the little thingy. (I know, such science). Pressures are fine. It's 1am here, I start orientation for my new job at 8:30am and I'm sitting here bitching about A/C because it's supposed to be 97 tomorrow and I have to park the Saablazer in a sunny lot all day.

Silly question, would the connector on the back of the compressor not being plugged in have any significant effect on the operation of the compressor?

Because I unclipped it and put it back in, and the compressor kicked on right when I fired her up.

My AC quit randomly one day and i disconnected the low pressure switch to jump it out with a paper clip to see if that was it. It cycled with the paper clip. Plugged it back in and it continued to work for about two years now. I chalked it up as just enough corrosion to prevent contact and just removing it and reseating the connector cleared off enough of the corrosion.
 

littleblazer

Member
Jul 6, 2014
9,265
My low pressure switch decided to die one day at work. In the 90s with 100 percent humidity. Coming down rt. 18 at 75 was interesting to say the least. Blast oven more than anything tbh.
 

therealsethallen

Original poster
Member
Sep 20, 2015
501
Western Mass.
It was the damdest thing. I'm almost wondering if this inadvertently solves my compressor's poor cycling at idle too, hopefully when I go out to the truck at 2:30 it'll be nice and cool when it spins up.
 

jsheahawk

Member
Jan 16, 2013
533
Kansas City
Silly question, would the connector on the back of the compressor not being plugged in have any significant effect on the operation of the compressor?

Because I unclipped it and put it back in, and the compressor kicked on right when I fired her up.
Double yes.
 

Billdaman

Member
Jan 19, 2012
32
This is a follow up to my A/C Acting strange at idle thread (See: Idle Hunting While Using Air Conditioning)
I replaced relay #44 with the horn relay, tapped the horn and it worked. So the relay is fine.

I did the same swap before reading your post. I have been chasing this same intermittent AC problem for months, finally solved it today. Pulled Relay 44 and replaced it with a different relay (Gave both relays a gentile tap) The AC never worked better and continues to do so. The Compressor clutch was cycling very weakly and squawking when it did. All noise went away after swapping relay position 44.

Did you end up switching the relays back to their original positions after you did the horn test? I just ordered 5 replacement relays to eliminate chasing other bad relays in the future, If the relay in position 44 failed due to moisture intrusion, the rest cant be far behind. Strange things happen to relays. A fragment of steel floating around can get magnetized and find its way in between the contacts. When I worked for TRW Electronics we used to get Ford warranty relays back from the southern US full of red ants. Never could figure out how they got inside a sealed relay!
 

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