CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Heater switch

The switch on my blower only works on high, is it the switch, relay, or what

Pit Mom, Usually It’s The Blower Resistor That Burns Out And Causes The Blower System To “Default” To High Speed Only As It Was Designed To Do So You Still Have Heat / Defrost.

Often a new blower resistor fixes the problem. Sometimes the new resistor is short-lived in the situation that a worn out blower motor is putting too much strain on the resistor. In that case, both blower resistor and blower motor / fan assembly need to be replaced.

Most people go with the new resistor, first. That will likely fix it.

Do you have basic manual heat / defrost controls as opposed to automatic temprature or climate control?

Also, I’m curious. Is that “pit” in “Pit Mom” like the pit in “pit crew” or the pit in “Pit Bull”?

CSA

It could be the resistor pack as CSA suggested. But the problem can also be caused from defective high speed blower motor relay.

This relay is what controls whether the voltage passes thru the resistor pack for the lower blower speeds, or it applies full voltage directly to the blower motor for the high speed.

These resistor packs for the blower motor aren’t cheap anymore. And I’ve seen people waste their money on a new resistor pack when the problem was with the high speed blower motor relay.

Tester