HVAC issues

[87SQRBDY]

Hello all, I am new to this and have a 1987 Chey R10 Silverado, small block 350 and looked every where for an answer, so I thought I'd give it a try here.

I'm having a problem with my fuse blowing when i place my blower selector switch on high. It doesn't do that in the first 3 settings, only when place on high.

I'm grateful for any help and advice.

 

[dusterdude]

My thoughts are,either a bad blower relay or maybe a bad blower resistor

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[Itali83]

The resistor is bypassed in high, so, you’ve probably got a blower motor going out and it is just drawing more amps than it’s supposed to. Check your switch on the back side where the plug is, over time they can get melted and broken from heat over the years, I’ve seen where the plastic plug is completely gone, the pins on the switch are loose and can touch other pins and short out possibly. My bet is tired blower motor though.
Ben

 

[Corvette Ed]

Welcome to the forum.follow the advice from Itali83 and you’ll find your problem.

 

[SirRobyn0]

The resistor is bypassed in high, so, you’ve probably got a blower motor going out and it is just drawing more amps than it’s supposed to. Check your switch on the back side where the plug is, over time they can get melted and broken from heat over the years, I’ve seen where the plastic plug is completely gone, the pins on the switch are loose and can touch other pins and short out possibly. My bet is tired blower motor though.
Ben

I agree with this. As other have said the resistor is bypassed on high, so really only leaves a failing motor. If you really want to test it you could disconnect the blower motor, make sure the unplugged witing isn't touching any metal and turn the switch to high and see if the fuse blows. Which I'm quite sure it won't. My money is on the motor.

 

[87SQRBDY]

Sorry just getting back to everyone. Thank you very much for all the help. I'll definitely try each suggestion. The motor isnt that old, bot even a year old yet, but that doesn't mean it cant be bad though. For the longest I was doing "shotgun" repairs to no avail. A couple times it worked for for a while then just stop for a few days then back to normal. Now it's just the high speed blowing the fuse. Apologies for being long winded. I'll try everyone's suggestion and get back with y'all tomorrow.

 

[87SQRBDY]

Ok all, I tried unplugging the purple wire that gives the motor power and the fuse still blew on high. I've changed the relay, resistor, even though I prob shouldn't have and the blower selector switch. I'm at a loss of what to do.

Thank you for the advice though because I def wouldn't have thought about the motor causing an issue like that. Good reference for me to put in my tool kit.

I'll get back to it and try to run down the issue.