What is this "sender" ?

Hi all,
Today i want route a pair of speaker wires through the front door and door jamb. I did it on the left side, there was a rubber plus (1") in the jamb so no problem (escept doors have no hole for wires ...)
But on passenger side i found a "metallic thing" fixed with two scew. I removed the screws and discovered that there were two wires at rear. I can't followed them as they go to interior.
What is this part which looks like a transistor TO3 !!!!!

On the pic you can see it between front of front door and rear of fender


rear of part (red color)

 

Does your car have air conditioning? It looks like it could be a temperature thermistor (a device that changes resistance because of a change in its temperature) that keeps the cabin from getting too cold, or keeps the compressor from cycling on too cold a day.

 

Hi Andrew,
Yes my car has A/C. A friend of mine who works in heating, boiler, etc... tells me that it looks exactly like some thermal switchs he uses ! I've the electrical schematics of '70 Ford and i can't see this part on drawings of A/C. Could it be a switch sensitive to external temp and turns off (or on) the A/C ?

 

I think it is, as my earlier post indicated. Nowadays, it would be known as an ambient temperature switch or sensor, and yes, it would control the clutch to keep the cabin from getting too cold or preventing the clutch from engaging on too cold a day.

 

Unplug it and see what happens?
I'd check the factory service manual, the factory assembly manual if they have it for that year, ask on a Ford forum, see if it has power and trace it back to it's source.
That plate could just be made to hold that plug and wire for an accessory that was never installed originally, like a power antenna or spotlight possibly.

 

The wire colors don't correspond with the power antenna or spotlight accessories, AFAIK.

 

This does indeed look to be a thermal SWITCH, not a thermistor. I also strongly suspect NOT related to the air conditioning either. A thermistor was probably employed near the evaporator to prevent icing, but this ain't it.
I know Ford used these in the early(primitive)emissions systems to inhibit the operation of certain solenoids, throttle solenoid being one.

 

Yes, but installed in the door pillar?

 

I'm pretty confident that's what it is. I've since looked at a (Mustang)wiring diagram and the wire colors (on a Mustang anyway) are red/yw & brn*
As for placement it would be away from engine heat, shaded with ambient air flowing over it. Makes sense to me.
* pretty sure it was brown, can't find that diagram again

 

If this device is to control emissions through the electric dashpot at the carb and the various distributor vacuum controls,there is another part in that circuit. On my Ford,it is a red plastic box underdash near the steering column. Inside it are various electronic components. On mine,it is burned out and disconnected. I knew that there was an ambient temperature sensor in a door pillar,but I haven't seen it on mine.

 

Fair enough. I'd have to see the sensor firsthand.

 

The burned-out module under your dash--does it have vacuum lines as well as wiring? If it does, it goes to what's called an "Electronic Distributor Modulator" and the pic in my Motor book shows a thermo switch in the diagram with a grey wire to it. If I can snap a pic and post it up, I will, but right now I don't have a pic resize capability, so please bear with me.

 

It appears to tie in with the cruise control.

 

Hi, i haven't seen all these messages, i was busy, thanks for your replies ... The car has no cruise sontrol. As i 've removed the upper dash panel i think i could see (this afternoon) where go the two wires (one is black and the other light grey).
I look at the 70 shop manual and there is an "ambient sensor" but only on the automatic climate control A/C and not installed in this area. This feature wasn't available on Ford.
Yes Andrew the pic shows a thermal switch that looks lile my "mysterious" item. If you can resize the pics i send you a PM with my email adress, so you'll be able to send me pics .

 

Love that picture! I don't have anything that clear in my Chilton's here. Most of what is in that pic is disconnected; the "electronic control module and solenoid valve" IS the red plastic box with burned out guts,and was bypassed before I got the car. The PVS valve is functional,but I'll have to check if it is still connected to the module. What worries me is that Speed Sensor--If most of this mess is disconnected/bypassed,couldn't this cause the stuttering/hesitation at 45-50 mph? Or,it could even be a vacuum leak where the module was bypassed.