Climate control not working properly
 

My climate control on my 1983 300sd has a few problems. It doesn't matter what button is pushed, it stays on windshield. I replaced the ccu with a rebuilt one and it hasn't changed. It also blows fuses. I cleaned the fuse box and replaced the fuses and no change. The weird problem is that when it is turned on, the windshield wipers cycle on a couple of times. Any ideas??? Thanks

Sounds like a bad ground


ground points:


https://www.startekinfo.com/StarTek/outside/12253/program/Chassis/54-100.pdf


climate control wiring diagram:


https://www.startekinfo.com/StarTek/outside/12253/program/ETM/ACC83-85.pdf

Thanks. I will check all that out

I found out the overheating fuse problem was the auxiliary pump. It was seized. Still haven't figured out the other issues

Glad to hear...what issues are remaining?

The wipers come on when I turn the climate control on and it doesn't matter what switch I push, it stays on windshield

I replaced the ccu and no change

The wipers...the ground info from Christuna will likely be a huge help to locate and clean the ground connections. That is what I'd do next; but, there is a fair chance the new CCU has been damaged from the current overload and defaults to windshield clearing.

Good luck!!!

Thanks

Before you mentioned this, I was going to suggest checking the aux pump. I've seen these seize causing the climate control to go into default which is defrost only. Did you unplug the pump.

I did. I just checked to see if the climate control worked and it is still only on windshield

The wiper is solved, I think. I unplugged the switch on the column and found a loose wire. I fixed it and now it doesn't do it now

I mean the wipers don't come on by themselves

Could the blower resistor cause the unit to default to windshield,also? I just noticed the low speed isn't working.

I don't think the blower resistor would cause this as all individual elements of it would have to fail. IIRC, the resistor is on the RF fender well in a metal cage. Check each coil for continuity and resistance.

Good luck!!!