AC compressor pressure switch, single pin?

[Joe B]

1990 K2500 7200 5.7 4x4

I decided to replace and fix my AC. I replaced everything. Condenser, evaporator, dryer, orifice tube, and the compressor. I had replaced the lines 5 years ago, so they still were good.

The compressor I got:
FOUR SEASONS 57237
https://www.rockauto.com/en/moreinfo.php?pk=816250&cc=1052301&jsn=10&jsn=10&jsn=10

I cleaned everything with the right ac cleaner, dried it out with the air compressor. I got it all together with the correct amount of oil and pressure tested it for an hour. The vacuum held. I kept the vacuum on for another hour to dry out the system and I notice that there was not a connection to the back of the compressor like my old one.

Looking through the electrical diagram, I found that it is the A/C Air Inlet Valve Motor Pressure Switch. From my understanding, googling around, it seems everyone else calls this AC compressor pressure switch. I've searched around and could only find pressure switches that have two pins. I can't find ones with only a single pin. I feel like I am searching for the wrong part.

I uploaded two photos of the old compressor, I tried to pull out the switch, but it ripped out when I tried. I also attached a photo of the electrical diagram too.

Can anyone help me out?

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[kenh]

The new switches are all 2 pins. One wire attaches to the original wire and the other goes to ground. JUST went through this with my 90 when converting to R134. Got mine at Advance auto 'cause I get a discount through my work place. I got the "kit" with the correct connector.

Ken

 

[arrg]

The single pin switches have been superseded by the two pin switches. You just change the connector. One wire goes to your old harness wire, and the other goes to ground. It's hard to tell from the photo, but, did you remove the snap ring before you tried to remove the old switch?

 

[Schurkey]

1. I think that switch is intended to operate the recirculation air door in the blower fan area. When the compressor is working hard, the recirculation door closes off the outside air.

2. I think I'm seeing the snap-ring still in the groove of the old compressor switch bore, if so, no wonder the switch didn't pull out.

 

[studigggs]

You dont have to hook up that pressure switch on 88-90 models (trucks with no 'recirc' button an HVAC controller). Just cut off the connector and ground the single wire on the harness. The system will move from fresh to recirc 30s after the A/C is called for in Med/Hi, full cold, when on dash vents. If you ever want fresh air on the A/C, either move the selector to partal floor, put the fan on low, or knock the temp one notch in the warm. I have the switch installed, and ended up grounding it full time because I never need fresh air when I'm trying to maximize cooling. You have no control with the pressure switch installed. That switch is not a high pressure cutoff...only controls the fresh/recirc door.

 

[Erik the Awful]

Yes, there's a snap ring holding it in. Mine's busted off, just like the picture above. I would worry about it if the compressor weren't locked up.

 

[Joe B]

Thank for all your replies. For the question about the snap ring, I did remove it, the plastic just fell apart.

As for the recirculation button, you are correct that I do not have one. If I don't need to hook it up, I will just get rid of it. My truck is black and is always hot. When I'm running the AC, it is always on full blast just keep it somewhat cool. If not hooking up the switch will make it even cooler, I'm all for it. Thanks for help.

 

[PlayingWithTBI]

Guys, you have to understand, THAT SYSTEM DOES NOT HAVE A HIGH PRESSURE SHUTOFF. You can get a pressure switch that comes on @ 200psi and shuts off at ~350psi and wire it in series with your low pressure cycling switch for safety. When it's hot outside and your engine is warm, you restart it, your pressures can spike way above 350 momentarily. I know because I blew out that switch (sounded like a shotgun going off), broke the snap ring groove, had to get a new compressor, and start all over again. After a lot of research, I realized the systems that don't have a re-circulation button don't have a high pressure shutoff either.

Edit - the switch I used was 200psi on and 430 off, I just checked my build sheet to make sure.

 

[Joe B]

Guys, you have to understand, THAT SYSTEM DOES NOT HAVE A HIGH PRESSURE SHUTOFF. You can get a pressure switch that comes on @ 200psi and shuts off at ~350psi and wire it in series with your low pressure cycling switch for safety. When it's hot outside and your engine is warm, you restart it, your pressures can spike way above 350 momentarily. I know because I blew out that switch (sounded like a shotgun going off), broke the snap ring groove, had to get a new compressor, and start all over again. After a lot of research, I realized the systems that don't have a re-circulation button don't have a high pressure shutoff either.

Where did you install the high-pressure switch?

 

[PlayingWithTBI]

Where did you install the high-pressure switch?

On the back of the compressor where the OE switch went.