plug on a/c compressor

[Abnorml]

On my 73 Cadillac hearse there is a plug on the a/c compressor and the bottom wire is not connected to anything. Does anybody know what it should connected to? The pictures are not the best, but I hope they help.

[Highbars]

One is B+ from the switch and the other should go to ground. It probably went to ground not near the compressor... Is it broken off or does it have a Terminal on the end...This connecter is for engaging compressor clutch... After and fuses or Pressure switches...

[Abnorml]

The wire is not broke, it's just not hooked to anything. It looks like it might go to the coil, but I'm not sure.

[Custom Coffin Works]

Mine goes to the plus side of the coil

[Morella]

Yes, one is to the dash unit and the other to ground, and if you have Climatron, it runs in every position except vent and off, if I remember right. I usually put in a separate switch to turn it on, instead of letting the Climatron decide. If you do that, though, be sure that you hook it up so that it can only come on with the ignition switch on.

-denise

[Highbars]

I'm goin' to the books.... been awhile since I worked in a caddy dealer...1979 was the last.... so I will do some research....

[Boogeyman Con Carne]

Here are a few quick shots from the dealer repair manual wiring diagram for 1973 Commercial Chassis...

[Boogeyman Con Carne]

Damn... those are crap... if they are heading in the right direction for you I will post better ones tomorrow...

[Abnorml]

Here's a picture of the wire. When it's plugged in it's on the bottom.

[STODD]

Ground it. The compressor will cycle after that.

[Psychoholic]

damn you people and your air conditioning!

[Abnorml]

Ground it. The compressor will cycle after that.

That's all it was. Thanks everybody for the help.

[Morella]

Hooking up the positive side to the positive side of the ignition coil is wrong! Nothing should be connected to that terminal except for the ignition wire. You are also bypassing the control head, A/C fuse, and thermocycling switch, if so equipped. If the compressor clutch shorts out, your ignition wire will fry, or, if it has a fusible link for the ignition, it will blow. Either way, you will end up stranded on the side of the road, unless you hotwire it. You are also taking away 3-4 amps that your ignition needs, limiting your power, especially on the high end, and reducing your gas mileage.

If you have a superheat switch, the negative side grounds through it, but most people who replace compressors don't move the old superheat switch to the new compressor, even though that may have been the only thing wrong with the system. It is there to turn off your air conditioning if the compressor gets too hot, to keep it from overheating and getting damaged. If you don't have one, then just ground one terminal of the connector, if it isn't grounded already.

Some cars have a thermocycling switch, to turn the compressor on and off. This may be necessary to keep your evaporator from clogging with ice, and it may save you gas. In this case, the positive side of the compressor goes through this switch and then to the control head. Some cars will have the compressor run all of the time, once it has turned off, so if you switch from A/C to vent, the compressor will still run. This is to keep moisture from building up on the evaporator case, and making that stinky odor when you turn on the A/C.

Do yourself a favor and fix it properly. I use a separate switch to turn mine on and off, but I know how the system works, and when to turn it on and off.

-denise

[Morella]

Let me elaborate on this, because I forgot something. In the cars which use a superheat switch, there is a fuse which looks like a rectangular block, usually on the evaporator case, and with green and black wires coming out of it. If the compressor is superheated, such as happens when the system is low on refrigerant, this fuse will blow, and your compressor will not get power. You will usually see a bulge in the fuse. You must replace it before the compressor can engage.

I believe it was 1977 when they went with the low pressure cutout switch in the line instead, and did away with the fuse. You can buy these switches to screw onto your service port on older cars, and they will cut out your compressor if the pressure is either too low (out of refrigerant) or too high (superheated). You can even buy them with R134 conversion ports on them. Try ackits.com and they will hook you up. If you don't have some sort of protection for your compressor, it will seize if the refrigerant leaks out, or damage the compressor or blow a hose if the A/C system overheats.

Hope this helps,

-denise