'92 fullsize blazer, heater problems

[nofeartruckin00]

\'92 fullsize blazer, heater problems

Alright, this is just annoying. The heater won't turn on when I hit the button. It waits about 3 minutes then the fan will start to blow. When I hit the fan speed up or down, I can hear the relay click but no fan.

As of today, the fan won't blow at all. I assume because I can hear the relay click every time I try to switch speeds it is still good. What do I actually need to replace, just the blower motor? Thanks for any suggestions you may have!

 

[HarryH3]

Re: \'92 fullsize blazer, heater problems

Getting to the blower motor on these is a real pain in the a$$. /forums/images/graemlins/frown.gif But you need to get to it and unplug the power wire. Then use a jumper wire to apply voltage directly to the power input of the motor. If it doesn't spin right up then it's time for a motor, unless you want to pry that one apart and try to replace the brushes yourself. They typically wear out and cause intermittent fan operation.

If it spins right up every time you apply power, then you'll need to start working your way back through the harness to find out where the power is stopping on its way to the motor.

 

[nofeartruckin00]

Re: \'92 fullsize blazer, heater problems

Thanks for the tips! Applied direct 12V and nada, so I picked up a new blower motor for $25. Being a PITA to replace is an understatement /forums/images/graemlins/shocked.gif!!! It took a good 45 minutes just to get at the stupid thing. I never knew the ECM was hiding back there behind the glove box, now I know what was rattling. The air blows again, YEAH!!! Thanks for the help! Now to just get the air to blow warm..... /forums/images/graemlins/smirk.gif

 

[HarryH3]

Re: \'92 fullsize blazer, heater problems

Glad to hear that you got it fixed! Getting at that freakin' motor isn't nearly as easy as on the earlier body style! /forums/images/graemlins/frown.gif

 

[KENNY]

Re: \'92 fullsize blazer, heater problems

LET ME ASK YOU SOMETHING. THE RATTLING NOISE YOU HEARD WAS IT LIKE A BUZZ THAT WOULD HEAR EVEN WHEN THE FAN WAS OFF.

 

[nofeartruckin00]

Re: \'92 fullsize blazer, heater problems

Nope, wasn't a buzz. It was only when the fan was on, and sounded like a marble bouncing around in the fan. The only buzz i've heard in my truck is when my headlight switch was bad, and when I hit the switch, the lights wouldn't come on right away but the electrical connections would buzz/crackle.

The only other stuff back behind the dash/glovebox is the ECM, and 3 relays (I'm guessing the relays are for high/med/low on the fan) Does the noise seem to come from that side? May want to check for a broken wire interfering with your radio, or maybe just the pass side speaker.