So, my parents have a 2004 S type that has some issues with the their HVAC. It's a digital display that shows they can adjust the temperature up or down and it shows the speed of the fan increasing or decreasing. BUT, nothing happens when they adjust the blower.

I don't live here so can't work on it too often. I came home to visit a few months ago and we replaced the blower motor and it continues to do the same thing. It will kick on once in a while but it's very random.

I'm not sure what to do. It's freezing cold and my mom can barely leave the house because of how cold the vehicle is. I'm in town for a couple of days but don't know if I'll be able to do anything before I have to leave.

Any help is very much appreciated.

 

Usually the DCCV - use Search - or its module (in which case both).

 

There's a relay (R7) for the blower motor, in the rear power distribution box. Wiring diagrams here, scroll down to figure 6.1:


http://www.jagrepair.com/images/Auto...x2062004en.pdf


The easiest way to troubleshoot is to swap a known-good relay with position R7. Look for the other relays of the same size and pick a non-critical system as a donor and swap them. See if the blower now works okay and if the fault follows with the suspect relay.

You can also check fuse F10 in the rear power distribution box. Make sure the prongs are clean and it is firmly seated.