in need of heater/ac help!!!!

[98 blazerlt]

i own a 1998 blazer lt with computer climate control and i have been having problems with the heater and ac...it seems as if the panel loses power because the heater control loses power and the defrost loses power.. i have spent several dollars on this problem and no one seems to know how to fix it...the heater will work when it wants to, right now it works but who know when it will quit. i been told it was the a/c-heater controller but before i spend $350 0n the part i need a second opinion.........any takers????thanks

[ricksza]

If the whole panel is losing power, the first thing I would do is determine if you are losing power to the control head. It might just be a bad connection shutting everything off. Terminal C6 (brown wire) is Ignition 3, terminal C12 (orange) is battery, and C10 (black) is ground. If it is an intermittent concern, I would wire in test lights to all three circuits. That way when the heater control shuts off, you can determine if you lost any of these.