I have a 2003 Chrysler Town & Country with the Automatic Temperature Control (ATC). It has an intermittent problem where the blower speed it selects for the temperature setting in the interior is very SLOW. For example, on 100F day and inside set to 60F, it will run the fan at about 1/4 the speed it needs to keep us cool. I try to manually adjust the fan speed to max, but it is usually unresponsive and does not increase the speed, and is nowhere near the max speed I know it can get to. Any ideas? I find it interesting that it is usually on really sunny days where the dash and interior gets a lot of sun. It usually starts out fine on a trip, but begins failing after some time.
Could it be one of the infrared sensors in the cabin that sense how hot the occupants are? Could it be some other sensor?
I have replaced the
1. blower speed control module
2. ATC control unit

Thanks
Peter

 

Can you take the system off of automatic and get full speed from the fan?

 

When I do take the system off of automatic, the manual fan speed adjustment does not allow me to adjust the speed for very long. It may increase in speed for a few seconds, and then drop in speed back to a low level, as if it is still in 'auto'. The fan speed is mostly unadjustable at this point with the ****. It's pretty frustrating to not even have manual adjustment!
It doesn't always give me problems, which makes diagnosis a bit tricky for me.

Could it maybe be a blend door, too? The fan was good the other day, but had weak output on the 'floor' setting compared to the 'panel' mode.

 

Do the led's on the panel change when you turn the ****? Plugged Hepa filter? The blower speed in manual mode just uses the control head and the power module. No sensor input should affect it.

 

The LED's do change when I move the ****.
I doubt it is HEPA filter, as it works 80% of time.
I have replaced control head, so I don't think that is it. For power module, are you referring to the integrated power module under hood? Any instructions on how to test it?
Thanks
Peter

 

It sounds to me like the fan motor is toast. When ours went out, it would barely run no matter what the ATC called for.

 

power module is what they call the blower resistor for the ATC system. Leaning toward the blower motor as well.

 

Thanks for the suggestions. I think I will try replacing the blower motor.