82 300SD Climate Control

[phil2810]

No blower motor, even in defrost setting. Still seems to get heat out of the dash when cruising at 45-70mph.

Removed the blower and hot wired it. Checks GOOD, blows hard and quiet. No 12VDC to it when everything is connected normal.

What wire color is the BLOWER output source voltage on from the CCU? I want to check it for an output.

I've read about the AUX water pump eating CCU's, I don't know if it's bad or not, but is the fact I have no blower even in DEFROST point to a bad Control Unit?



What does the "Blower Regulator" do (I saw it while I was under the dash)? Also, Where is the Resistor Block? I figure they must both be in between the CCU and the blower itself, therefore possible.

I don't know if this is the right idea, but I'm thinking the system must be like this:

CCU output voltage pin ----Resistor block --------blower reg------blower motor


Thanks.

Phil

[Brian Carlton]

If you have no blower in any position, but the blower is good, either the CCU is NG or the blower controller is NG.

I suffered with the same problem for a month last winter and it turned out to be a bad CCU.

[tangofox007]

Originally Posted by phil2810

I don't know if this is the right idea, but I'm thinking the system must be like this:

CCU output voltage pin ----Resistor block --------blower reg------blower motor

It's a bit more complicated than that. The blower regulator is actually powered (Red/Yellow wire) in parallel with the CCU, but receives input from the CCU as to operating mode and selected fan speed. It also interfaces with the Temperature Control Unit when the Auto fan speed is selected in some modes. The blower regulator determines how many elements of the blower reisitor are utilized in order to operate the blower at one of the six possible speeds.

My guess as to the most likely cause of your problem is that the solder joints in your CCU are cracked.