Hello everyone,
I'm new to this forum so please bear with me. I have a 2003 Astro van LT, and it runs great, but I have a problem with heating and a/c controls. It blows hot or cold as it should on low and medium speeds but when I turn it to high it stops blowing all together. Could use some help
thanks

 

The resistor block is probably the problem. Does the fan blow on every speed setting except high?

 

The RESISTOR,AUX A/C BLO MOT(TWO THERMAL LIMITERS)Its found on my 97 under the hood left side facing the engine,On mine I had the remove the radiator and windshield wiper reservoir??/I belive mine had three or four wires going to it??/ it controls the speeds to the fan,as mine did not work on high either??/It fits in the shroud of the fan,I guess to keep it cool when operating??/Someone way back when said you can wire the high speed side directly(red or orange on my vehicle) And I've done this on earlier models,but I wouldn't advise it because of no protection in that circuit??/ So I bought mine(Heater/AC fan resistor)through Rock Auto parts store(cheep closeout)and found out why??/ I had to remove material around where the old resistor fit into the fan shroud (The template was supplied) , because the new unit was bigger than the factory opening maybe a plus because of added insulation and component strength??/look at the old one when you remove it to see if any of the circuits are fried??/ at this point you can run 12 volts directly to the fan to find out if it runs faster than normal use from inside the cad (Touch and go)

 

be careful here. The high speed control bypasses the thermal resisters with a relay to supply 12vdc directly to the fan motor. The relay is in the same pack as the thermal resistors. All controlled by the fan speed switch.

 

Thanks for all your insight guys. Yes the blower does work on all speeds but "high". I am familiar with the resister in this case, as I have replaced it about three years ago. I had to do the modifications to make it fit. I didn't think it would go bad in just three years. I'm going to go ahead and replace it this weekend. Again, thanks for all your help.