I bought a 1997 bonneville with auto temp control, and the display only has three short equal lines displaying. It does nothing. no fan, no heat, nothing. The radio is missing, and the heater core has been bypassed. Will the bypassed heater core cause the auto temp control to shut down? The a/c compressor clutch runs all the time. Any tips?? thanks.

A bypassed heater core would not affect the electronic climate control system. I'd assume the problem is with the HVAC Programmer (which is attached to the plastic cover over the heater core), the climate control head, or the wiring between the two. If a sensor or actuator (perhaps the ambient air temperature sensor, or the air mix actuator) goes bad, the outside temperature will blink upon starting the car. In this case, it is larger problem.

My money is on the climate control panel. It'* the easier of the two (vs. the programmer) to replace.

Nick

Did you check your fuses? I had a blown fuse that did the same. It was a small red 10 amp, 3rd row last fuse i think.

Well...here'* the deal I bought a replacemant radio, and when the radio did not turn on, I replaced the blown radio fuse. And vioalį! My control unit started working as well as my radio! I almst dripped 80 bucks on a used one but I just had a hunch the missing radio may have something to do with it. And no, the fuse that was blown wasn't the temp control fuse. Wierd.