Heater not working? Need help

[FastOrange]

Check the printed circuit board on the controller for lifting on the trace. I have had dozen's of these over the years that worked until you touched them. I junk a dozen trucks a year and 96-98 hvac controls are getting hard to find in working order.

we checked that, its fine.

plus the fan speed doesnt use the circuit board.

 

[great white]

This is going to sound simple and you might have already done it without mentioning it here, but try removing cleaning and reinstalling the dash wiring harness grounds.....

 

[FastOrange]

This is going to sound simple and you might have already done it without mentioning it here, but try removing cleaning and reinstalling the dash wiring harness grounds.....

Haven't done that yet, where are the grounds located?

 

[great white]

This is a 96 tahoe and not a pickup:

http://www.gmtruckcentral.com/wiringdiagrams/1996 Chevrolet Tahoe/Fig 2 Heater Circuit.pdf

So it looks like it's using the common engine ground through the firewall.

My 98 has it up under the RH side of the dash.

Looks like you can find it either way by following the ground wire on the blower motor.

Have a look and chase it down....

 

[FastOrange]

This is a 96 tahoe and not a pickup:

http://www.gmtruckcentral.com/wiringdiagrams/1996 Chevrolet Tahoe/Fig 2 Heater Circuit.pdf

So it looks like it's using the common engine ground through the firewall.

My 98 has it up under the RH side of the dash.

Looks like you can find it either way by following the ground wire on the blower motor.

Have a look and chase it down....

We checked that ground, it's on the front side of the block near the crank sensor.

Plus that same ground controls the heater motors, which are working great.

I'll still take a look, maybe clean it up abit.

 

[FastOrange]

worked on this again today.

someone told me to check the plug that the red wire goes to, they sometimes get loose and cause problems.

found the plug rolled up in the factory foam .

cut it out, splice the wires together.

no dice.

 

[1997chevydriver]

Just double checking here.....


Ok he said this....vvvvvv

check the body side connector (male) for the fan speed on the back of the HVAC controls, I had the same problem you had TWICE, the resistor was drawing to much current and melting the wire, I bet your connector is melted man.

And you said this.....vvvvvv

just put the fan out of my 1994 in my 1996, fan is a OEM Delco, works great in Orange truck, same problems.

its not the plug on the back of the controls, i had 3 different controls in it last couple days...

Did you check the connector on the controller? Or the plug on the harness in the truck that plugs into the fan speed switch?

 

[FastOrange]

This plug with the blue tab right?

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And here is the one in my other controller, all seem fine

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[FastOrange]

I just realized, the switch it self has 3 contacts on the top, but the plug only has 2?

 

[1997chevydriver]

This plug with the blue tab right?

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And here is the one in my other controller, all seem fine

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Not sure if its just the angle or not but the black wire almost looks melted to the tanish wire and the blue wire about 2?" Back looks a little funny? Possibly melted.

As for the extra pin I'm not sure