Okay, among a lot of other things I'm trying to do on my 69 300, I would like to be able to turn on the A/C. My compressor is seized up, and before I got the car, somehow the wire connection for the clutch was removed. What I need help with is finding out which wire under the hood to connect to the A/C compressor when I put one in that works and has an actual connection to plug it in to.

I found one that looks like a candidate. It looks black but it may actually just be a very dark blueish green. It's got a female blade connector end on it, and it attaches to a bullet connector near the firewall behind the passenger side valve cover. See the attached pictures.

I put a battery in the car and pushed both the A/C and MAX A/C buttons and checked for a voltage in this wire, and there was nothing, but it may be because my fan resistor is unplugged. When I got the car, the resistor was broken in half and the plug was melted. After 11 years, I have a replacement but haven't got around to putting it in yet, because when it was running, even without a fan, the heater core radiated so much heat into the car and combined with my laziness that resulted in me never fixing the fan. So if there is some kind of interlock with the fan that doesn't let the A/C clutch engage unless the fan is turned on, that could be the reason.

Any insight into this issue would be appreciated.

Another picture, closer to the firewall to show where the wire originates out of the wiring harness.

I was so happy to see that I had a response, then I remembered it was me.

It looks like it, but I cannot say for sure. I do not think the resistor has any application to the AC clutch though. That is handled by the control switch in the dash. You may have a blown fuse, which would explain the lac of voltage.

I'm not specifically familiar with the 69 300's AC, but in general, AC systems have a pressure switch that keeps the clutch from engaging if there is inadequate refrigerant pressure in the system.

My guess is that your system has 0 psi in it as the compressor died a horrible death many years ago.

Now my other concern, if you simply install the new/rebuilt compressor in the car, you will soon have a pile of junk again on your hands. Especially expensive if you loaded scarry expensive R12 back in.

When the compressor died, it seized and filled the refrigeration lines, evaporator, orifice and condenser with shards of metal. You need to replace the receiver/dryer, flush out the entire system with solvent under pressure from both directions on the orifice (they make stuff to do this), load the correct amount of oil into the compressor and assemble the system with R134 fittings. Since R134 does not like old lines, I'd consider replacing them at this time too.

Once this is done, see if it will hold a vacuum. If not, find the leak. Then load R134

Astrobuf

The pressure switch that disabled the A/C system on low pressure was not introduced until after 1969 for Plymouth and Dodge; don't know about Chrysler. Plymouth diagrams show dark blue colored wire from the firewall to the compressor clutch connector. The wire after the connector to the clutch is usually light green. But you need a 69 300 wiring diagram and FSM.

When the heater is off, no coolant is supposed to be flowing through the heater core, and the doors inside the heater box should be closed. Maybe the vacuum hose/vacuum motor system and vacuum switch that control the heater box doors isn't working properly. If the heater core was hot, sounds like the coolant valve wasn't closed. Start troubleshooting with the valve, then the doors. If your dash controls are shot, that could explain both the heater hot in off and clutch wire not hot when A/C on.

Yes, if the compressor cratered internally, the entire system is contaminated with metal debris that is usually visible in a black coating on the expansion valve and at pipe ends. All piping/hoses, the condenser, and the evaporator must be flushed with flush fluid and shop air (about 100 psi), NOT an aerosol flush can. For an example of a flush tool, see:

http://www.northerntool.com/shop/tools/N...g%2Bflush%2Bkit

Replace the contaminated accumulator/drier and the expansion valve. Flushing will remove all refrigerant oil, so the oil must be replaced with refrigerant compatible oil, either R12 oil or R134a oil per the FSM, a few ounces each into the new compressor, new accumulator, and each heat exchanger for the specified total amount.

This photo shows a Plymouth dark blue clutch wire running to the front of the valve cover terminating at a connector and a light green clutch wire after.