1989 heater issue

[tim1]

The guy across the road from me just bought an 89 convertable that is having issues with the heater. The digital display will only go to set it up to 60 degrees, he purchased another control unit (junkyard) and it is doing the exact same thing. Can someone please shed some light on where or what I need to start checking so we might be able to get his temp to go up so he has hot air.

 

[DonB]

You should check for any fault codes stored. They will lead you in the right direction. I have a '90 and the procedure may be different because many things changed from '89 to '90. I'd definitely check the FSM to be sure.
Here's how I access mine anyway.
Push and hold the fan up and fan down button at the same time and hold for 5 seconds. The LCD will show "-00" Then push the AUTO button. The system will then display the fault code stored. Here's what they mean,
00 Not Used(no fault)
01 Temp. door motor circuit fault
02 Temp. door motor circuit fault
03 Ambient sensor open
04 Ambient sensor short
05 In car temp sensor open
06 In car temp sensor short
07 Solar load sensor open
08 Solar load sensor short
09 Low(or no) Freon
10 UART Failure

To clear faults disconnect the negative battery lead for ten seconds. This will also clear any and all presets in the car.

Let us know how you do.
Don