ac/controller power problem 94 C4

has anyone seen this problem?
the power to the a/c head seems to go off/on at random intervals. the backlighting doesn't go out, just the temp digits int he lcd and the green
light over the button selected. when it comes back, it goes through the normal power on sequence (showing the internal setting, then the outside temp).
it does it randomly, the time off is random, when sitting at a light, and also, oddly enough, will occur sitting in my garage with the engine off but the ignition on.
i've swapped out the controller head with the one from my wife's 96, but the problem did not follow the controller. i've checked the fuse for this circuit and there is no corrosion in the fuse socket, and replaced the fuse. i drove around with the head sticking out and moved all the wires that go into the head without being able to cause the problem.
i don't have a manual for this car, so can't find out where the ground points or power is provided. is there a relay that provides power, or something else like another controller (besides the esm) in the circuit that could cause such an intermittant problem? the bundle of wires dives behind the dash down into somewhere near the driver right foot, but i can't seem to figure out how to get the side panel off, or know what else it's connected to there.
thanks, charlie
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