High Fan Speed Relay Keeps going out

[aj213121]

Hello, my highest speed on the A/C was not working so i replaced the blower resistor/wiring, as well as the switch/wiring. After that didnt work i replaced the high speed relay and it worked! But here I am a week later and I believe the relay is dead once again. The first one looked like it was melting a bit, so I'm assuming there's too much power draw? But how would i go about fixing that?

 

[shucker1]

You might start looking at the fan motor itself beginning to wear out or drag.

Excessive amperage draw causes heat which burns up the boards.

Amperage and Voltage are inversely proportional so if voltage goes down amp draw goes up for the same amount of work.

Wouldn't hurt to check the idle voltage of the alternator and the voltage output of the alternator @ 2000 RPM to make sure it remains almost constant.

Outside chance the alternator is putting out less than optimal voltage causing excessive amperage draw by the fan motor.

 

[aj213121]

Thank you! Maybe I'll replace the motor next and see how that goes!

 

[ptf18]

Somewhat OT but what are opinions on replacing high mileage alternators (200k plus) as a preventative item instead of getting stuck on the side of the road?

 

[Mbrooks420]

Agree with Shucker. I’d suspect the fan first.

As for replacing a functioning alternator, I wouldn’t bother unless you are going to replace it with something at least equivalent. I’d trust a 200k unit over a cheap reman anyday.