Environmental Control Works when it wants to

[LostSoul]

So my heat and AC work...when they want to. Everything works as it's supposed to eventually but not when you change the switches. I have had it apart a few times. Checked voltages and signals. Resoldered the board in case it was a bad joint. (Not the Colorado kind). Since everything eventually works I am assuming the solid states are good. I don't have any hair so I can't pull that out. It is the kind that is thermostatically controlled. I am at my wits end with this thing!

[Jemstone]

I'm not a mechanic, but that sounds like a break in a wire.  A break in a solid wire wil open as the metal cools and contracts, opening the break and disabling the a/c and heater fan.  When the metal is warmed by the heat generated by the engine the wire expands, closing the break and allowing current flow.  The break may be in a wire where the insulation both hides the break and keeps the wire ends almost touching.

Get a can of liquid nitrogen and spray the wires slowly enough to pin point the likely short.  I am guessing a computer repair place would know where to find it.  (Once you have a flash freeze aerosol you are also set to have some serious fun with food, especially thin sliced items.)

John