A/C wiring

[Jose0404]

I have a 91’ sierra 5.7 that tha wiring to the A/C compressor was cut. Found the connection at the junk yard but I’m not getting any power to it. It doesn’t have Freon so I know the clutch won’t engage but shouldn’t I at least get power? I get power to the pressure switch on the drier when I hit the A/C button. Also I don’t see where the switch behind the compressor hooks up. Any help would be appreciated. Previous owner did some sketchy ass wiring.

 

[pressureangle]

If it's the same as '94, the power goes through the low pressure cutout switch on the accumulator and won't pass power until the system is charged. Test power at the accumulator switch.

 

[tsr2185]

Just did a bunch of ac work on my 91

There is only a low pressure switch on the dryer, which cuts off at 20psi. You can unplug this sensor, and jump the plug with a paperclip. This will bypass the low pressure switch and send power to the compressor for you to test when you turn the AC on.

There is no high pressure switch, just a relief valve at the back of the compressor. Ive had this relieve pressure once when I was charging system and orifice tube was clogged, that scared the s*&^ out of me!