NoSparkplugs

So now that its summer and its obviously getting hotter, driving with straight air at my face isn't going to cut it so I want to get my AC going again. Now I've 90% sure that I still have refrigerant in the lines but anythings possible I suppose. My main problem is that the clutch on the compressor won't engage, like its not getting any power. Where would be a good place to start looking on it? As far as I know everything is hooked up and I recently discovered that the pressure switch (I believe thats what it is) was unplugged so I plugged it back in with no difference in operation

So for those of you who have tackled the AC system on the glorious 1st gens, what are some of the easy to check and replace items on the system?


Thanks

cootz

I had this happen earlier this year as well.
First check the fuse. Its an odd ball fuse, mine was anyway, the ones where you can't visual tell if the fuse is good or not. Either replace it with another fuse or use your test light to ensure power is getting past the fuse.

If everything is good at the fuse, either your clutch itself is shot or there is a problem upstream. Use a test light to ensure you have power at the clutch itself when the A/C is engaged. Work your way backward if no power is found. Mine had a loose electrical connector on the passenger side wheel well. Unplugged it, cleaned the terminals, replugged, and presto, its like the North Pole once again.
And to think I spent a 28C day stuck in traffic in Red Deer sweating my rear off when it was just a loose connector.

wannadiesel

Didn't you have PCM trouble last year? The PCM runs a relay that grounds the compressor circuit. If you have a problem with the crank sensor, the PCM will think the engine is off and won't engage the compressor.

NoSparkplugs

I'm still not sure if my PCM is ok or not. My cruise doesn't work and I *think* my clockspring is ok (I figure its ok since my speedo and odometer work fine). And the CC servo holds vaccuum fine as well. Maybe my crank sensor is shot and needs replacing? If the crank sensor IS shot what would be a sign of it being inactive?

So far I've checked the wiring and it seemed to check out, nothing frayed, broken or loosely connected.

wannadiesel

And you haven't put a voltage regulator on the firewall? It's hard to remember who's done what...

If it's charging using the factory setup, the crank sensor is OK.

Try jumpering the pressure switch harness to see what that gets you, you may just be low on refrigerant due to a leak.

NoSparkplugs

The alternator charges fine. I haven't replaced the voltage regulator yet but I don't see the need to.

Ok, how would a guy go about "jumpering" the pressure switch harness. I haven't heard of that one before .

BearKiller

There are two wires/contacts that the pressure switch makes/breaks the circuit to.

Either skin a portion of those two wires, or un-hook the switch, take a short length of wire and "jump" between the two wires.

If low refrigerant, or a bad pressure-switch, is the problem, the compressor-clutch should kick in, when the switch is by-passed/jumped.

If the clutch kicks in with the switch by-passed, check the refrigerant pressure.

I ain't no A/C specialist, so please correct me if I'm wrong.

wannadiesel

That was exactly what I meant. It's a poor-boy way of checking to see if you just need refrigerant.

NoSparkplugs

Well while putting on the new belt tensioner I tried jumpering the pressure switch and I got nothing from the compressor. I turned the clutch part of the compressor and it turns but it doesn't feel 100% smooth.

So now I think its something a lot more involved and expensive .

wannadiesel

OK, now let's hot wire the compressor to make sure it's not seized and that the clutch works. On the driver's side fender there are 3 relays. The rear one is the A/C relay. Pull the plug off it and (with the engine running) jumper the dark blue wire to the dark blue with a black stripe. If the clutch engages and the belt doesn't slip, we know the compressor isn't seized and the clutch works.

It sounds to me like something simple and electrical.

NoSparkplugs

Man I hope your right Dave, I swear after hunting down various wiring problems I think Dodge should've hired an actual electrical engineer to design the wiring on these things.

Where would I be without good ol' DTR? Probably stock and going slow .

NoSparkplugs

Ok so I jumpered the wires as Dave said and voila! I have ac and its super cold as well. So now its just a matter of finding the electrical problem.

However, while hotwiring the compressor, I found a maled ended plug, unplugged. It has green, pink, black/white and 2 blue wires running to it. I didn't see any female ends without a mate but I'm pretty sure this plug has to connect something.

KB440

That's great you have somewhere to work from.

The other connector you see is the OBD connector or DRB port whichever you would like to call it.

wannadiesel

OK, the way the circuit works is this:

Power comes out of the PCM to the cycling switch (near the pressure switch, 3 wires), then from the cycling switch to the pressure switch, then into the HVAC control panel, then is grounded with a whole bunch of other stuff. When the PCM sees a complete circuit, it kicks on the A/C relay and the compressor comes on.

Test the PCM/relay function by unplugging the cycling switch and grounding the brown wire with a jumper. Do this with the engine running and the A/C turned on. If no joy, leave that wire grounded and go unplug the A/C relay again. Use a voltmeter to look for a ground on the dark blue/orange wire. If you have a ground there, swap another relay into the A/C position and the system should run. If you have no ground there, it's trouble with the PCM or the wiring harness to it.

NoSparkplugs

Ok stupid question but what colour are the wires on the cycling switch? Its hot and crappy here again and I'm hopefully going to have my truck back tomorrow from the shop and my weekend project is to get the AC working like it did from the factory.