I found a problem with my AC today, worked fine on the way to waor and on the way home, it quit blowing, except on full blast. It is not just the AC, it is the system altogether, it doesnt move any air or operate in any way except on level 4. Any ideas, I have no idea what could be the cause of this. Any help would would be appreciated.

 

Might want to check out this thread towards the end.

https://www.dieseltruckresource.com/...d.php?t=111716

 

Sounds like something is broken/blocked... I assume the fan switch works in all settings and you're just not getting any flow except on the max?

There are issues with the blend/recirculation doors. I'm sure someone will point you to how to fix yourself or take it in and pay $. Lots of people seem to have this issue.

 

NO, MJ i know exactly what your talking about, mine does it too!!! only on full blast some times, them if you just take off or go around a corner it works for alil while then back off, you can sometimes hit the switch and it will pop back on again, MEGA, IT IS THE SWITCH and it is shorting out. it didnt start doing it till this summer when i used AC alot, then just started doing it all the time. i just havent had time to take to dealer, if they will even replace it.

 

If it only works on high, but not the other positions on the switch, it is more than likely the blower motor resistor. They use it to change the voltage for the speeds of the fan.
Part Number #4720278
List Price: 62.95 USD

 

already pulled mine out and tested it with ohm meter, its the contacts on the back of the rotary switch.