Stephencs601

My 1984 A/C compressor is not working. The only way it turns on is by giving direct power to the wire in front of the timing cover. Has plenty of freon in system. Any thoughts.

SharkSkin

Start here: https://www.928gt.com/T-WallyHVAC.aspx

IMHO the best thing to start with is the freeze switch. With the AC control head/AC button calling for AC you should have +12v on both terminals of the freeze switch. This cuts troubleshooting in half(usually). Based on the results of this test you may find:

• 12v on both terminals -- something in the engine bay(usually) is what is causing the break in the circuit. the wire does go back to the CE panel to connect to the harness for the engine bay so it's possible a CE panel connection could be at fault. Try the same test on the low pressure switch that is on the side of the dryer.
• 12v on only one terminal -- freeze switch probably faulty
• 12v on neither terminal -- problem inside the cabin, probably either fuse, relay on CE panel, or relay inside control head.

Stephencs601

So far this is what I have found. The connection to the AC button was unplugged. When the radio was installed, they must have pulled it out and never replaced it. I have no power to the recr/dryr. So what I will do tomorrow will be to check the freeze switch. Now If I have power to both sides I Will run a new wire to the Recr/Dryr from the freeze switch. Any thoughts on the above.

SteveG

Yea, wonder why it was unplugged. I hope it is just the freeze switch, BTDT. If that doesn't work, you may have a problem with the relay in the control head. There is/are write-ups on replacing this with a stronger relay; involves removing the head from the dash, soldering, etc.. If you don't find what you need, PM me. I'm in Sound Beach most weekends, I can get a copy of what I have to you, but I may not have inet this weekend, computer glitch at the house there.

Stephencs601

Steve,

I think it may be the wire from the freeze switch to the recr/dryr. Will test tonight. Call me over the weekend. I will be home all Sunday

SteveG

Stephen: I don't have your number?? PM. On my GTS, the wire to/inside the probe was intermittant; I couldn't see any way to fix that, so I had to replace the whole thing, but it is easy, IIRC not much $$. If you are talking about the connection from there to the dryer, that should be simple too. I hope saying that doesn't jinx it for sure.

dr bob

Remember that the pressure safety switch and the 14-pin connector are between the anti-freeze switch and the clutch. While it is always possible that there is a bad wire, the most likely candidate is the pressure switch doing its job. You can test the switch with an ohm meter for continuity. If there's no continuity across the switch itself, most likely that you have low freon in the system due to leakage. Fix the leaks, new drier, evacuate, refill. Take the opportuninty to restore the oil level in the compressor while you have it out for new o-rings and hoses. But fix the leaks.

Stephencs601

I know that I have Freon. Has been checked when we jumped the compressor.

The fan did not come on when we jumped the comperssor. Is that normal. On that 14 connector, which is the wire for the switches.

dr bob

How did you check the freon when you jumpered the compressor? Pressure gauges? Do you have continuity through the pressure switch?

WSM electrical drawing shows that the clutch connection runs through pin 9, and that connection is between the pressure switch and the clutch. So as you are tracing with the ohm meter, starting at the upstream side of the freeze switch, you should have continuity to the other side of the freeze switch, then the upstream connection of the pressure switch, to the other (downstream) side of that pressure switch, then to the bottom (stationary) side of the 14-pin connector, connects to the engine (top) side of that same 14-pin connector, then the wire to the harness side of the little compressor plug-in spade terminal, and finally connected to the compressor clutch lead that plugs into the harness there where it passes by the oil dipstick tube.

You should also look at the WSM pages (97-205) to see that the circuit passes in and out of the CE panel. From the freeze switch, it passes in through J2 and back out through Q2 before going to the pressure switch.

The fan will come on when you have high freon temperature. Just jumpering the compressor will not necessarily start the fans.

Stephencs601

Found the problem. I checked the freeze switch, both sides had power. I then checked continuity from the switch to the power block in in the engine. This is what I found; a wire spliced and not connected and another wired hooked up to it running into the interior. I checked continuity from that cut wire and found it was the compressor wire. Some nut cut that wire for something else. Gee I wonder if every time they turned off the A/C the thing didn't work Losers.

So problem fixed for now. Thanks everyone, I owe you a drink.