Help: heater repair

Hi,
My heater control fritzed out; smelled like burning wire under dash, then the controller blanked out. Dealer thinks its either the heater controller, or the heater resistor
block.
The controller is easy to replace but expensive; the resistor block is cheap, but is very hard to get to (under dash behind blower motor). Does anyone have any suggestions on replacing the resistor block?
Thanks, Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Guess it would help to say its in a 91 GMC P/U (with half its dash out now). :(

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Answered own question. Trick was to see the schematic from the dealer, rather than Haynes or Chilton. The dealer's schematic showed the resistor block sitting on top of the heater assembly near and not immediately behind the blower motor.
Resistor was discolored but not broken. Will swap test controller to see if its OK. If it is OK, any ideas on what else could be wrong? I put power to the fan and the motor is OK, so the problem is between there and the controller.
Thanks Ian

then
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
My local Library has a set of Mitchels that are much better than chiltons or haynes crap. I refer to them when I dont have the oem manuals.
Cheers

Does
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mitchels. Thanks. I'll look for those.

resistor
is
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Look for a 6 pin connector behind the controller and pull it apart. Most likely its fried. Common on these gmc's. My connector was directly behind the controller and easy access, I have heard others say to access it remove the glovebox and it is there. Good Luck and plz post your findings JRE
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Problem had multiple causes.
There was a resistor in the controller module that was blown. My nephew (an electrician) found and replaced it; saved replacing the entire contoller module.
The resistor block which looked OK didn't test OK. I replaced it. May have been the source of the problem with the blown resistor in the controller module.
The relay (6 pin connector) in a bank of three similar devices in front of the resistor block behind the glove box (not behind the blower fan as my book showed) is OK.
There was still no power to the controller module because of a poor ground. Everything worked except for the fan. Instead of trying to find this, I ran a new ground the blower motor directly to the frame. Everything now works but the blower motor is noisy and a little stiff. Probably needs lubrication or a bearing; will take this apart and repair tomorrow. This may have contributed to overloading of the resistor in the first place.
I would like to check the filter (if there is one) next to make sure it isn't clogged with dust. Do you know if there is one and where it is?
Thanks for all the info.
Ian

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.