I have an '85. My AC/Heat does not come on. I tested the blower and it works. My Haynes does not have a section on AC/Heat. I am taking it apart and examining components, and I found this odd little part. The coils are intact, but slightly corroded. There are remains of ceramic coatings on the wires. Here are some pix. Anybody know what this does?
Carolyn

 

I think that was for the AC, whenever the air flow through the vents was cold enough that icing of the compressor could occur, it would kick out the compressor, untill the air flow warmed up.

 

The problem was that the blower wouldn't turn on. I checked the blower motor and it works. Next I took out the switch, and as I was taking it out the blower came on for a couple of short bursts. So the problem is in the switch or the wiring right near the it. Does anyone have a wiring diagram for the switch?

 

Those are the resistors for the blower. They control the different speeds. 99% sure on that. Theres full wiring diagrams and FSM with a great heater TS section. Look in the FAQ thread for the linkie.

http://www.iluvmyrx7.com/1st_gen_manuals.htm


http://www.wankel.net/~krwright/cars/cars.html

 

Werd to Carl.

 

Oh yeah thats right, the frost switch is mounted elsewhere, sorry

 

Yep, Carl's on it.

The ceramic coating that you see intact on some of these denotes it's purpose to resist current flowing to the fan so that you have 4 speeds on your fan control. Speed1 is all resistors, Speed2 is 2 resistors in the path, Speed3 is 1 resistor to the flow, and full Speed is straight 12v current.

If you run a voltmeter across your terminals looking for continuity, you'll find which ones are working correctly, and which ones will need to be replaced. Often, what can happen is that these resistor wires get cracked under the ceramic where you can't see it which results in losing one or more fan speeds - you will ALWAYS have full speed, which is unresisted 12v. A trip to Radio Shack can net you some good resistors that can be soldered into place, but as for resistance ratings, you'll need to check with the FSM or wiring diagram. Since these are mounted in the flow from the blower fan, they do receive cool air across them to keep them cool, but they also generate heat that is released into your airstream from the A/C - something to think about if you're into not wasting energy (thermodynamics).

I run my A/C at full blast most of the time for this reason. HTH,

 

Where exactly was this located. The resistors on my 79 apparently are shot. I only have full fan speed. I do not have any slower speeds. Hopefully you can save me a lot of time and keep me from taking a bunch of stuff off that I don't have to.

Thanks!

 

Remove your fan motor and the 'thingie' is located in the upper shroud that the fan motor assembly bolts into. You'll see that it's about 1" by 3" and has all of the ceramic coated resistors mounted to it. The wiring harness that connects is on the outside, with the resistors on the inside of the duct.

HTH,