Return it to stock, I want my controls to work as intended.

 

I forgot to add that the blower motor control module can be removed to access the inlet, outside facing side, of the evaporator. When I removed mine out of curiosity I found almost the whole area packed with tamarack needles and small leaves. It is worth taking off to check.

This is a link to a control module. They are expensive but I'm sure you could get one at wrecking yard for cheap.

https://www.rockauto.com/en/moreinfo...314133&jsn=469

 

Since you have the automatic climate control system, your blower motor does not use a resistor network to vary the speed. The speed is varied with a PWM (pulse width modulation) signal on the purple/white wire which comes from the Heater and AC Control Module on pin C16. The black wire is ground and the orange wire is hot at all times power. I suspect that when the system failed then the PO substituted a std blower motor and ran a switch to the power for the motor to produce full output blower speed. If I am correct then you will need the OEM PWM blower motor and then return the wiring to stock. What we dont know is if the blower motor failed or the control circuit failed. Either way the std blower was most certainly cheaper. If its the control circuit that failed then you will install a new/reclaimed PWM blower motor and the system will still not work until the rest of the failure is corrected. Unless you have an oscilloscope then it will be hard to verify proper pulse width modulated control to the motor prior to spending the money/swapping parts. If you get access to a proper PWM motor at a junk yard then you could wire it in under the hood and see what you get.

As far as the hot air is concerned, does the compressor clutch engage and does the accumulator get cold and sweaty with a call for cooling? If not then its probably not your blend door/motors/vacuum. If yes than the converse is probably true.

George

 

George,

I like your hypothesis about how the wrong blower motor might have been installed. To satisfy my curiosity I checked to see if there are different blower motors for the manual and automatic climate control systems and there are. The thing is there is not much difference in price between them, at least now at Rock Auto. I would guess it is the PWM circuit at fault, i.e. the control module, that might have gone bad.

 

I see that Christine is right about the motors being both inexpensive and nearly the same price so I'll go with her guess that its the controls that probably failed. The PO either did not want to spend the money or did not want to tackle a more complicated system and went old school. Of course we will both be wrong if the PO just happened to have this motor laying around.

George

 

How do I tell the difference between the motors?

 

Hard to tell, it’s just me so I can’t really watch the clutch (assuming I am looking at the right thing) and hit the button at the same time, but the accumulator did not seem to get cold after running the air conditioner for a few minutes.

 

Old school used with a resistor network for speed control = 2 wire.

OEM PWM control for your truck = 3 wire.

George

 

Look at the front of the compressor and with no call for AC the very front plate will be stationary even though the belt and pulley are turning. Call for cooling and then go back and look again and that front plate will be spinning. Also the whole thing will chatter a little and the RPM's will change slightly.

George

 

OK it doesn’t work then, that front plate is as still as can be.

Think it’s a bad air conditioning clutch or could there be a problem somewhere else in the system? What should I look for now?

I suppose the good news is that the blend door actuator might actually be working then.