So this car has been sitting for a few years and I've just now started resurrecting it due to fuel costs, and now its running like a honda should. When I parked it a few years ago my A/C stopped working and my lasting thoughts were that the pressure switch was bad because it had 134a in it but compressor or condensir fan wouldn't come on. All fuses seem to be good.

So before I just throw parts at it, could you guys give me a starting point to run with?

TIA 🍻

 

If you have a set of gauges, put them on the car. Is there any pressure in the system? How much?

With the engine running, apply +12V to the compressor clutch with a jumper wire - does the compressor engage? If it does engage, what kind of pressures are you seeing on the gauges?

 

No pressure in the system. I jumped the pressure switch on the dryer, the clutch does not engage. Clutch engages when I direct power the red wire. Fan not running either. Relays seem to all be good, not sure if they are getting a signal. When I press the A/C button on the dash, it does not illuminate.

 

Anyone know what the electrical chain of command is with the a/c?
I'm stumped.

 

I just went through replacing a condenser because it was leaking. The chain of command from what I know is simple.. When the a/c button is pushed on the dash it sends an electrical signal to the a/c relay which activates the a/c system. If the pressure switch sees no pressure, it will not activate the a/c clutch. But the a/c condenser fan comes on. You don't have either of these. First check the a/c switch in the dash, if that's not working, nothing will. Also, test the pressure switch, that could be bad as well. But the relays can still be bad, have you checked them manually? Instead of assuming they're good, test them out, can't rule out anything.

Look around all of the components and look to see any oil residue around, that's how I found my condenser leak. But with no pressure you need to see if there is any refrigerant in the system. If no pressure, no a/c, get that hooked up to a a/c machine to see how much refrigerant comes out, then you'll know there's also a leak.

 

There is no refrigerant in the system whatsoever. This car has been sitting a long time. I do have manifold gauges and vacuum pumps, and will get to that once I know all the electrical is working. No signal to the pressure switch either. I've checked the relays and they're all good. I guess it could be the a/c switch on the dash. Not sure what else it could be

 

ok so we now know it's leaking.. obvious to look for the oil residue where it was leaking.. shouldn't be too hard to find that, should have lots of grime on those areas. But testing out the a/c switch on the dash, testing the relays out and then replacing them, there's only 2. I had an a/c clutch relay that tested out correctly but there was this loud CRRRRACK first time the a/c was turned on. I thought it was the clutch since the relay tested out good, replaced the relay no more noise! So that tells ya.. plus the relays are cheap $$.

Ok so no signal to the pressure switch at all, not that the switch is bad, no signal getting there. Simple start, check the a/c switch in the dash, and you might have to do some continuity tests from the a/c switch wiring down through to the pressure switch. Ya a/c switch is where it all starts...