checkmate1996

Ok, while I had my radiator out, I did a quick resistance check on the temp switch on the lower, right front of the raditor. NADA, nothing. I did confirm a circuit completion of I just touched my two leads together to verify my unit worked. So, do this mean my switch is bad?? Time to replace?

SharkSkin

Assuming the switch was not at operating temp, your test shows that the contacts are open, as they should be. What you really need to know is if it closes the contacts at the right temp. Switches are available that switch on at 75°C/off at 70°C (a common swap) but the original part is on at 95°C/off at 90°C.

Your next step should be to put it in a pan of shallow water -- preferably not on the bottom of the pan, suspend it or put a plastic kitchen spatula on the bottom of the pan and the sensor on top of that. You want the sensor immersed as far as possible without shorting the leads. Now increase the temp of the water while checking for continuity at the leads. You should get continuity at no more than 95°C (within a degree or two).

This is one thing that may be easier to check in the car(except you already have it apart ), either by holding a thermoucouple tightly to the side of the radiator near the sensor with something that won't act as a heat sink, or use an IR thermometer.

Imo000

Wouldn't the switch be open when cold and when it reaches the target temp it closes the circuit?

SharkSkin

I think that's what I said...

checkmate1996

Dave,

Thanks! Great tip!

Imo000

YUP, you certainly did! NOW look at the time we both posted our responses and it will all make sence!

SharkSkin

DOH! I get it now...