a/c not working

[92astro]

1992 astro TBI engine ok i ohmed out the pressuer switch and it is closed and i ohmed out the clutch on the compressor it is good. ok with the engine running and a/c set on i get "0" volts at the pressuer switch. what is the problem is it a relay and how do i test??

[peter]

Did you check the high pressure switch for a closed circuit?

[92astro]

not yet where is it and how do i acces it and can you post a pic please??

[peter]

It should be somewhere on the high-side section of the refrigerant piping. I have no clue whatsoever as to where on your truck, though. Follow the lines, son....

[92astro]

will the high pressure switch look like the low pressue??? also is there a wiring diagram for the air conditioing system??

[peter]

Yeah, I would think that the high-pressure cut-out would look the same. There surely is a diagram somewhere. Seeing as you wanna wrench on your truck, why don't you go on EBay and look for an OEM service manual for your model year. It'd help immensely!

[92astro]

well i looked everywhere for that high pressue switch and took the doghouse off and still could not find it. i am gonna look at the relay and the selecter switch what else could cut the power to the low pressue switch???

[92astro]

hey peter i came up with an idea to check the compressor clutch, ok, i would disconnect the connector on the clutch then i would run a wire from the clutch to grould, then run another wire to the postive side of the battery then start engine the clutch should engage then the compressor shouldd start pumping!!! just to make sure the compressor is good! to text it. also i could run a hot from clutch to battery and negertive to battery

[peter]

That'll work, 'xcept you don't even have to start the engine. You'll see/hear the clutch pull in...
The hp cut-out is on the rear end of my compressor. Upper terminals near the pulley are power, rear set are hp switch.

[92astro]

okay thank-you peter i will be testing this here in a little while!! so i will report back!! if it does work i might rig up a toggle switch to turn on/off the clutch!! but that is my last resort. the problem might be in the selecter switch. but don't know yet. i do have knowledge of electric and heat and air because i am on my 2nd year of heat and air, and there is lots of electric involved.!!!

[92astro]

i just tested the clutch it pulls in just fine so that is good.

[sfeaver]

If you have no power on the light green wire at the pressure switch, check if you have power at the AC selector switch, that is fed with a Brown/White wire. If that has 12 volts, then your mode selector switch is bad.

If Its still dead there, check at the fan speed switch. That is fed with a brown wire, if that doesnt have any power then check your fuse. If it does have power then the fan switch could be bad.

There is no high pressure switch on a 92 from what I can see on Mitchell.

Scott

[92astro]

okay i will look at the selecter switch i bypassed the whole control system and ran one wire to the positive side of the battery and ran the other wire to the negative side of the battery the clutch pulled in just fine i ran the engine and i engaged the clutch the compressor came on just fine, but it does need 1 or 2 cans of refrigant. but thats it it runs great no adnormal noise. so i know the problem is on the control side.

[LiftedAWDAstro]

If it needs 1 or 2 cans of refrigerant, the low pressure cut out switch is what is holding it up. Unplug the switch and jumper it. Make sure the van is running and the controls are set to A/C. Just jumper the 2 wires and it should kick on.

[SoCalli V8]

You can find wiring diagrams at http://www.Autozone.com