A/C wiring.

[jkeys0218]

I have an 85 K5 with a 91 TBI 350 in it. The truck came with a compressor, condenser, lines, and accumulator all new in boxes. However it seems to be some 91 parts and some 85 parts. Compressor is and R4 with no high pressure switch and the accumulator doesn't have a low pressure switch.

I believe the original 85 setup would have just had the low pressure switch in the accumulator and the wiring is still there for that. Can I bypass this or do I need to get a new accumulator with the switch in it?

Also what color are the wires for the compressor clutch? I have a few unused wires under the hood but none that reach to the compressor.

 

[mechted]

Wiring diagrams:
http://brochures.slosh.com/wiring/

 

[jkeys0218]

Thanks for the link. These are layed out better than the set of diagrams I have. But I dont see any A/C wiring on either set.

 

[Wes Harden]

how many test ports on accumulator, if 2 the low side pressure switch can be screwed on to 1 of the ports. power from a/c switch in dash goes to one side of low pressure switch, the other side goes to the compressor coil. This will work with an orifice tube meter system. you need a diode at the coil between the power and ground. I used a relay to turn the coil and condenser fan on.

 

[frankin5]

This is from 91 GM manual, should help

 

[jkeys0218]

Thanks guys you both helped a lot. Only problem now is the low pressure switches I am finding are for r12. I will be using r134a. Do i need a special switch or is the r12 one fine?

 

[frankin5]

looking for this
https://www.autozone.com/cooling-he...itch/santech-a-c-switch-mt0207/157503_24901_0

 

[Wes Harden]

https://www.autozone.com/parts/cool...itch/santech-a-c-switch-mt0205/175014_24901_0 this with https://www.autozone.com/parts/cool.../santech-a-c-switch-mt0135/930089_293323_6389

 

[jkeys0218]

Yup. I found some threads on converting r12 systems to r134a. There should be a screw between the terminals that will adjust the switch, 1/8 turn should equal about 2lbs. So once its charged I should be able to fine tune the switch while watching the gauges.

Thank you everyone for your help. This forum is an amazing place. Ive only posted a few times. But ive spent many hours reading old threads and have learned so much about these trucks.

 

[Toymyster]

Thanks guys you both helped a lot. Only problem now is the low pressure switches I am finding are for r12. I will be using r134a. Do i need a special switch or is the r12 one fine?

R12 pressure switch will work fine. You pressure switch will not care what refrigerant you're running. Unless your new accumulator is threaded for 134A fittings (5/16") Mine has the R12 ports and I had to install a 134a retro fit connection on one of the ports. ope this helps.