ATC - 88 Estate Wagon - how much does it control?

[occupant]

I picked up this beast for $600 today and the AC compressor works and all the lights and functions of the ATC unit work...at the head...but the blower motor is out and the heater core is disconnected. I'll check the resistors and the motor shortly, change out the heater core, but I want to know two things:

Can the ATC unit prevent the fan from coming on if the light for the selected speed lights up and it beeps? Low, Auto, High, I get no fan movement. I'm ASSUMING that the fan motor is shot or a resistor is blown, but I just want to know if the problem COULD be part of the ATC head unit.

Does the ATC system use vacuum to move the blend doors or are they electric? Since the fan doesn't work, I don't know if the air is going to come out the right place, so I am curious to know how this system works. Maybe there is a theory page somewhere on the net and I haven't found it yet?

[Hawken]

I have seen many of these in a few local junk yards. Is there a part you can ID that you need? Maybe post some pics.

Ken

[Greg Schmelzer]

They can be a pain. I'll have to get back to this with pics tomorrow. I have an 84 Electra that the blower motor would not shut off at all unless you disconnected the battery. There is a circuit board on the top of the A/C box that is bad. I bypassed the circuit board and installeed a rocker switch in the dash to control the fan on/off. The speed switch in the control panel will still vary the speed. It just would not shut off. I'll post some pics tomorrow.

[71staged]

Hi Alan,

The Electronic Touch Climate Control automatic air conditioning system,(RPO 68), uses electric motor-driven actuators, rather than vacuum-operated valves, to direct the air flow. The keypad contol panel directs the input signal to the blower and a/c compressor clutch control module, situated atop the blower and a/c evaporator housing. This module has a 2 pin and 5 pin connector. It's possible, if the wiring to and from the module is OK, and the blower motor is good, the module may be defective. Try cleaning all the contacts for the module, as well as the the pin connectors. Remove the screws retaining the module to the blower housing to access the other connectors, for cleaning. If cleaning doesn't help, the module should be replaced. The module is still available through GM, but pricey at $190 Cdn., and GM parts prices effective March 2009 , will be increasing 10%.
Look for another module, or bypassing it, as Greg already suggested.

Good luck,

Nando.