76 Eldorado ambient temperature sensor

[7gen]

Can anyone confirm that the prongs for the electrical connector on the ambient temperature sensor on the evaporator plenum are in line as opposed to at right angles?

In cold weather, the blower does not come on until about 20 minutes into the ride. Cadillac Tim diagnosed this as an ambient temperature sensor going bad. Easy fix, right? I got an NOS sensor for a 76 Eldorado from a vendor and the prongs are different from the one on my car. The one on my care are two prongs set side by side in a line. The sensor sent to me by the vendor has the prongs set at right angles to each other.

I looked on ebay and mine resembles what someone is calling a 73 sensor so I'm wondering if it has been changed out on my car and a 73 installed? The electrical connector, though, looks original and it only allows prongs set in line to be connected.

The prongs look like this one on ebay. I haven't taken the sensor out to look at the business end to see if it looks like the unit shown, though. http://www.ebay.com/itm/Delco-1973-Cadillac-A-C-Ambient-Temperature-Sensor-NOS-Part-15-7642-/142133334803?fits=Year%3A1973%7CMake%3ACadillac%7CModel%3AEldorado&hash=item2117ce9313:g:rzAAAOSwSHZWc2WM&vxp=mtr

Could someone take a look on a 76 Eldorado convertible and let me know? Thanks.

[Scot Minesinger]

The switch on the e-bay listing is installed on the evap casing adjacent to passenger hood hinge and looks correct.  Tim may be referring to the switch in dash unit, not sure.

There are two delay switches that wait until car is proper temperature to start the climate control working.  One is behind the alternator and it makes ground.  The other is in the dash unit itself and you have to remove and replace it (solder in as I remember).  These two switches are in parallel for a/c but not heat.  The heat switch is behind alternator, and if it is triggered a/c and heat will work right away.  To make sure this is not part of your problem remove wire from single spade connector behind alternator and attach a ground to the removed wire. If the system operates then that is the problem.  I routinely ground those to remove the delay feature. 

[7gen]

Thanks for the info. It may be easier to just do as you say - ground out the heat delay. The temperature control dial inside the car works great once the system comes on. All functions are good - three blower speeds, automatically stepping down or up depending on the in-cabin sensor determining cabin temperature. Heat changes in response to control dial. So maybe all I really need is to ground out the heat delay feature entirely. I'll try that this weekend.

Thanks!!!

[Scot Minesinger]

Believe me it is the very best way to manage this.  If you regularly parked the car outside during extremely cold weather and started it wearing exposed ankle clothing, then the delay may be worthwhile.  For ac it is completely worthless to me, and not worth it for heat.

[cadillactim]

Perhaps you misunderstood. The ambient sensor is not what I was referring to. I was stating that the heater turn on switch behind the alternator may be going bad.

The vertical spade sensor is the compressor switch. It prevents the compressor from coming on when the temperature is below freezing.

Tim

[7gen]

Yep, my bad. My problem is that I'm starting from nothing in my understanding about engines. I looked up ambient temperature sensor in my shop manual and went blindly from there, without understanding that there are sometimes several names for a part. I apologize - I'm really trying to learn. Mostly, I've been been finding parts for my mechanic but I want to start doing more myself to learn by doing. First time out of the gate, I get it wrong. Sorry.

Is this the unit we are talking about? http://ezautoparts.ecrater.com/p/9667306/cadillac-climate-control-blower-delay

A better view of a different listing http://www.ebay.ca/itm/322289260450?rmvSB=true

[TJ Hopland]

That looks correct but between 70 and 90 ish there were at least a dozen different temp set points on sensors that looked the same.   The set points ranged from 120*F (the one you need) to in the mid 300's.    Luckily the 120 one is easy to test since the engine normally gets that hot.    Your existing sensor may be working but just the wrong temp setting.

That sensor grounds when it reaches its set point so its easy to test with an volt / ohm meter or test / bypass the rest of the circuit by grounding the wire. 

[7gen]

Well I guess I'll stick with just grounding out the switch as Scot suggested. I don't really find a use for the feature given how I use the car. I'll try that this afternoon. Thanks!!!