Air conditioning compressor not getting elec.

[jiggityjoe87]

I'm working on getting the a/c in my 94' 2500 working. when I hit the a/c button on the dash the climate control shows "a/c" but the compressor doesn't engage I have checked all the connections coming off the compressor and none of them are getting voltage when I push the a/c button. I have poured over my haynes manual and have not found any difinitive a/c wiring diagram does anybody have any recomendations what my next step should be. Keep in mind that this truck has 250,000 miles sooooo if there are any tests that I should be doing please let me know.

[scotts62]

Kind of sounds like a broken wire to me, since it is lighting the button that means the power is going in and out but not to the compressor. Have you followed the wire in the engine compartment for a broken or pinched wire?

[speedygonzales]

Wouldn't it also do that if the refrigerant were too low to activate the pressure switch?

Test light to the switch near the accumulator.

Need a good working elec diagram. Doesn't the Haynes manual have one in the back? Albeit crappy it could help us.

[Shyguy]

Yep, if the freon level is low the compressor will not receive any electrical from the pressure switch.

[truckdude239]

jump the switch on the side of the acculamtor and see if the compressor comes on if it does it is low on freon and or that pressure switch is bad. pressure reading with gauges should be between 30-45 on low side and 175-275 on the high side with the ac running. only charge threw the low side. freon charge not running should be equal on both gauges normal with compressor not running it should read about 100-120 psi on both. if its below about 80 its probley low on freon. feel

[truckdude239]

did you figure this out yet?