Help! Heater blower shutting off.

[bigfeet]

I need input guys! My heater was fine for 187k. Last week it was on high then stopped all of a sudden. Stays off for about ten minutes then comes back on. Always very hot. I took a shot and put in a new resistor. No luck, still shutting off, then coming back on. One interesting note, when I start truck heater blasts on high no problem. If I let sit in driveway, after about ten minutes blower quits. Once I get in and start driving for 5 minutes, blower kicks back on! When working I have all 4 speeds. Any ideas will be appreciated. Thank you all.

 

[SunlitComet]

only thing common in all four speeds is that it uses the same 2 wire connection at motor and the motor itself. you can eliminate the high power circuit if when it fails the other lower speeds do not work either. at each speed the electrical path to motor is slightly different.

 

[bigfeet]

Thank you. I do not want to eliminate the high power circuit. I should check connection at motor then. Sunlit, should I change the switch or even the whole module or is that useless?

 

[SunlitComet]

disconnect the motor terminal wires and test the voltage on the wires as you cycle thru each speed. jiggle the switch a bit in each speed to see if the voltage wonders off. try that first.

 

[bigfeet]

will do thanks

---------- Post added at 03:53 AM ---------- Previous post was at 03:52 AM ----------

Where are the motor terminal wires?

 

[clownracer]

will do thanks

---------- Post added at 03:53 AM ---------- Previous post was at 03:52 AM ----------

Where are the motor terminal wires?

right above the motor.....my connection was bad on my old tahoe i would wiggle it and the motor would pop right back on

 

[jrsavoie]

The connection is a known weak spot. More GM undersized wires.

This connection frequently suffers from meltdown. Especially on older motors that are pulling a bit more juice than they used to.

Might want to look into swapping the blower motor. I'd try to find a old stock AC Delco or check where a new stock AC Delco is made before buying. If you have to buy Chinese junk - it just as well be cheap Chinese junk

I usually add a ground from the ground spade on the blower to the dash mount bolt just a few inches away

 

[hagar]

You can also try wiggling your heater control panel and see if it turns off and on. Mine would come off and on at random, and when i wacked the control panel it would turn back on. Ended up being the one wire in the connector going into the heater controls had some build up on it. I just cleaned it good with sand paper, then pried the tab down a bit for better bite.

 

[jrsavoie]

The ground is close to the passenger side and just a hair above the bottom of the glove compartment.

The positive wire is just to the right of it.

The plug that you can pull apart is less than 6" away. follow the wire>

This is the plug that frequently melts down. If it shows deformity, change your blower motor. You will be doing it soon anyway.

It's easiest to start by removing the glove compartment

will do thanks

---------- Post added at 03:53 AM ---------- Previous post was at 03:52 AM ----------

Where are the motor terminal wires?