DaveCF

Gentlemen,

The previous owner of my '73 replaced the factory A/C with an upgraded unit (Alma Products) a number of years ago. The A/C has been intermittent currently, blowing cold then normal. I checked the wiring and discovered an unattached wire coming from the wiring harness (see picture). I don't know if this was done intentionally (if it simply wasn't needed on the newer compressor), or if it has detached from where ever it is supposed to be attached. I've found a wiring diagram for a 73 (no A/C) and a 77 with A/C, but it didn't specify what that wire did. Any suggestions?





Unattached black wire from harness





This is the harness, black wire comes in at bottom right.

jnb5101

That's the thermal limiter. It shuts off the compressor when the freon level is too low.

DaveCF

Sounds rather important. Where do I reattach it? And thank you!

Blue73Shark

In the picture below, 2 green wires and a black wire enter the socket that holds the thermal limiter. The black wire is on one end.
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jnb5101

Use this.

Mashman

The round connector it the superheat cutoff switch connector.

I believe this is unique for 72's and 73's. The round connector is plugged into the superheat switch on the back of the compressor. The superheat switch worked like a thermostat, and would provide ground if the compressor overheated - this would occur if the system had a leak, and was low on freon. This would cause the thermal limiter fuse to blow, and stop power from going to the compressor.

When you initially charged the system, you need to leave the connector unplugged, remove the thermal limiter, and jump the two green wires on the connector. This process is described in the service manual.

If you don't have the connector on the back, you could still have the original compressor, there is a plug that can be put in if the switch is removed. If you don't have the superheat switch, or it's not connected, then you should not have a termal limiter plugged in, and the two green wires need to bridged, to power the compressor.

DaveCF

Great, thank you all!