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Blower Relay Keeps Shorting Out

I have a question, and am wondering if anyone else has the same problem. I had my blower relay replaced under warranty in February of this year, because it was shorting out, and was causing the blower to turn on even though the dial was in the off position. It now is happening again, and will get it replaced again, and again, under warranty, since I’m under 60,000 miles. Anyone else have this problem, and know what could be the cause?

I have one possible theory. The parking lot where I work is a gravel lot, and don’t know if it just keeps getting dirty because of the dust and uneven surface. I don’t know where the relay is on this car, but that’s just a hunch.

The most common cause for a relay to fail where the component it controls continues to operate is because the contacts in the relay get so hot that they weld themselves together. This is caused because the relay contacts aren’t rated for the amount of current that passes thru them.

When you have the relay replaced next time, have them perform a current draw on the blower motor to see if it’s over spec. If the blower motor is drawing too much current, this can cause the contacts in the relay to get hot and weld together, and the blower doesn’t shut off.


I suspect that something is wrong with the wiring that controls the relay unless the relay contacts are fusing together due to a very excessive current rate due to a bad blower motor. The current needs to be checked as Tester stated. If the current is normal then something in the wiring for the relay control is causing the trouble.

get it tested as tester suggests, but if it passes muster there, the thing that is wrong in the leads will be either an intermittent short, or high resistance on the ground lead of the high current side of relay, at least that is my best bet.

If the contacts that the relay plugs into are loose/dirty, then that can cause heating at the relay that might burn it out.

Hi everyone.

Just an update. I had the blower relay replaced again, but that wasn’t the problem, as the blower was still intermittently turning on even though the dial was in the off position after it was replaced. In tracing it further, they determined it’s a bad switch. The part is on order, and also covered under the bumper to bumper warranty.