All the wires on the AC side of the weather pack are red. I looked at the position of the red wire on the Car side of the weather pack and applied a 12+ source to its mate on the AC side. The compressor did not kick in. Is this the correct way to run the 12+ to the compressor to force it on?

Of note: I did find that probing the AC side of the weather pack with 12+ gave me a lighted bulb with my tester in the middle slot. This would be the blue and red wire on the car side. So I assume it is a ground. Sound right?

 

Try this troubleshooting:

 

So I was searching to find where the Heater control panel was... OMG inside the dash... Anyway got some work to do there.

But in searching I came across a thread that mentioned a DTC testing. I was not sure it would work as the LED does not work in the AC button, but thought what the heck! So I follow the instructions. I release the Reserc and Defr buttons wait a few seconds for the Reserc to give me the results. Then the blower motor kicks in and blows air for a few seconds then shuts back off. No blinks from the Reserc. And yes the fan switch was off.

Is that normal or does it indicate anything else before I disassemble the dash?

 

So as a way to help rule out issues I wanted to pressure check the lines to see if maybe the whole thing is low freon and shutting the sys down. From searching I see its the caps that indicate indicate high and low pressure lines. Well both caps are gone on both lines. Which is which? Which one should I check to see if I'm low? I remember in some of the tons of thread I read that the high side should be 240-300 and the low 26-36 psi.

Is there a specific kind of pressure gauge you need to use to test the Freon. I have one that we used to check the fuel pressure on my 80s firebird. Will this one work?

 

You need an A/C manifold gauge to test the pressures. These are sold at most parts stores, it may be behind the counter and you'd have to ask for it.

But no need for that yet, you can just unplug the pressure switch and measure its resistance. It is an on-off switch-- if the pressure is OK switch resistance will be near zero ohms. If switch is open, it could be no pressure or a bad switch, you would need gauges to tell the difference.

I would be concerned that the LED in the A/C button never comes on, this seems like a control panel problem. The panel gets power from at least two different fuse circuits.

 

regarding the manifold gauge, you can rent them as well I believe. the high side is the smaller diameter tubing. but run the test that mk says and his point about the electrical problem also needs attention.

 

Is the pressure switch the one that is located on or in the compressor? How do you locate it? Do you just follow the wire bundle down I have been working with?

In alot of threads I notice people are jumpering the relay. Is there a need for that test in my case? And which relay is it? the one with the snowflake by it? How does one jumper these?

Would checking these help me determine if I do have an issue that requires dash removal. Just not looking forward to it since its the daily driver right now... Could mean driving around with the dash in pieces...

 

Questions regarding photos and information in post #7:

1) For the life of me, in the service manual, I can't find a 3P junction connector that feeds three RED wires into RED, BLU/WHT, and BLU/RED wires. Do the three RED wires go to the A/C compressor?

2) In the circuit diagram, a BLU/RED wire does run from the compressor clutch relay in the under hood fuse box to the thermal protector of the compressor. If this wire were supplied with battery power, the compressor clutch should engage (make click sound).

3) In the circuit diagram, a BLU/WHT wire connects the multiplex control unit to the A/C pressure switch (located on receiver/dryer). With the key in ON(II), grounding this BLU/WHT wire would indeed cause both fans to run, but should also cause the compressor clutch to engage (make click sound).

4) How did the 3P connector get damaged? Why are BLU wires seen sloppily spliced together in the photo?

 

Yes they all go down to the AC compressor in black tubing. Wonder if its an aftermarket unit?

the receiver/dryer... this is the unit with the blue and red wire feeding it? Mounted on drivers side in front of the fender well down low?

Well I got both fans to run, But I had the weather pack unplugged. I applied ground to the car side of the connector when disconnected. It would not have fed back to the compressor. I will retry this test with the plug connected.

Welcome to my used car nightmare. The connector seems to only be superficial and limited only to the plastic. I plan to solder the BLU wires back now that I found them. I found this when I peeled back the convoluted tubing to trace wires to help determine routing. The cars past shows a bad front end collision which totaled it. We were aware of the wreck when we bought it. Its how we got a steal of a deal. The deal looked everything over at the time we bought it. All seemed just fine. It has been working perfectly for us for the 10,000+ miles we have had it. Well until now.

 

Yes, I would guess an aftermarket A/C system was installed. The wiring looks bad, so I must assume the problem lies there. What components do the nasty spliced BLU wires serve?

The diagrams below show component locations and the A/C circuit diagram (partial, missing heater control panel). This may help you sort things out.