I believe the system test sequence is the same until you get into the all electronic (no vacuum) units in 1992. I will look at my 1989 FSM in a while and scan the test procedure. I may have a control head for that one.

 

The control head has a different PN on 1988 and 1989, but I believe the test procedure is the same. Here are the 6 pages from starting the self diagnostics through the end of the codes and then the connectors.

I may have some parts for it, but would have to see what I have.

 

Thank you very much for your time, I did the test and there was no codes, One test I did was I removed the ATC box and unplugged it and turned the ignition to on and with the box unplugged the Blower still turned on, The box must send information to something and whatever info it had already sent is stored in that, Like if you unplugged the digital dash for instance the mileage info is still stored so when you plug the dash back in the same mileage will come back up, I'am 99% sure when I first got the car the blower and display did not come on every time I started the car, It just doesn't make sense for any car to do that, I wonder with your shop manuals if it says where the ATC sends info to and if we can figure that out there may be some info or sequence of buttons you push-hold down etc...That stops the blower and ATC box from coming on by itself? In the display It also always lights up the AC snowflake, It might be something in the AC section, Sometimes the blower comes on half speed and sometimes full, When i turn the key to the on position the display lights up snowflake, The temperature and blower speed, If i touch the AC button and turn the snoflake off and turn the blower to high and then hit off, When i start the car again the snowflake always come on, and even though I turned it off with the blower on high it normally comes back on at half speed, But sometimes not often high speed? It's probably an easy fix, I have no codes and everything works good, Blower motor low high speed, Temp. Up Down All the icons in the display light up, Thanks again for your time, All The Best, Cheers Greg G

 

When you say you removed the ATC box and unplugged it, are you referring to the control head in the dash? If that is the case, then I would suspect that the power module (located on the HVAC casing under the passenger side of the dash) as that is what controls the blower speed. The system has a large power transistor that is inside the HVAC case so air flow from the blower is always cooling it.

The blower on these cars is powered from the accessory circuit, and grounded by the power transistor to control speed. If the blower comes on even with the control head disconnected, I would suspect the power module portion.

The wiring diagrams are for a 1988 Lebaron coupe or convertible, if you have a sedan, it may be different.