Bad thermo switch?

[1962nova]

My car currently has 16" Afco fan with relay connected to a thermoswitch right next to the thermostat housing. I have a Autometer Ultra lite II temp gauge on the opposite side. The thermoswitch is supposed to be 185on/170off, but it is not coming on until around 198 and off at around 185 based off my temp gauge.

Is this a bad switch or did I get the wrong one?

The fan relay kit is from Summit, and they have to temp ranges....185on/170off and 200on/185 off.

Thanks for the help,

Kent

[CarlC]

Have you checked the accuracy of the gauge? Also, have you confirmed your relay kit is set for on/off at 185/170? Your 198/185 is correct based on the higher of the two choices.



If you have a 180* thermostat the fans will not turn off if the fans are set to 185/170. Once on, they won't turn off again.

[1962nova]

Have you checked the accuracy of the gauge? Also, have you confirmed your relay kit is set for on/off at 185/170? Your 198/185 is correct based on the higher of the two choices.

If you have a 180* thermostat the fans will not turn off if the fans are set to 185/170. Once on, they won't turn off again.

I have not checked the accuracy of the guage. I have a 160 thermostat in. The thermoswitch is fixed temp, once it reaches the desired temp, sends a neg current to activate fan. So either I have the higher of the two thermoswitch or my guage is not reading accurate?

[thoroco]

When checking fan switches I use an instant digital thermometer used for cooking. Put a pan on the stove and bring the water up slowly with the switch connected to an ohm meter as the temp rises to the fan on temp you will see the ohm meter go infinate, then look at the thermometer, thats your on temp. Drop ice in the water to get your off temp.

Most less expensive fan switches can has a +- of about 8-10 degrees, good ones 2-5 +- but expect to pay $40-$50 for it.

Checking the gauge is similar. Boil up some water bring it to the car and with the temp sender probe in the water along with the digital thermometer read the gage and compare with the thermometer.

How do you know if the digital thermometer is accurate? You don't but you will know how the fan switch is working in relation to your gauge. If the switch comes on at 180 and the gage read 180 your in good shape.