HVAC fan only works on high

[Optikalillushun]

But i have all other functions. Worked fine last time i used it, about 3 weeks ago. Gunna check the usual suspect but any other suggestions? Is the speed slector on a cable or vacuum? Trucks an 88 F350 Custom with AC.

 

[160k87F250]

I would suspect the blower motor resistors.
John

 

[OLDBULL8]

The resistor block is located in the fan box.

 

[Optikalillushun]

Ya, im gunna look at the usual suspects first. Whats a good place to get a resistor? NAPA?

 

[dgr]

Just about any parts store should have the blower motor resistor. Oreilleys has it on the shelf but that may be a west coast store

 

[89dieselbko]

had this issue on my bronco... i replaced the resistor, didnt fix it, i had to replace the fan itself... the internal wiring was fried after (many years, its an 89) and just needed a freshening up. 5 bucks at local yard to fix it!

 

[f-two-fiddy]

More than likely the resistor pack is fine. The connex corrode and dont make contact

 

[Optikalillushun]

Thanks, started easy and ended up cracking the resistor pack removing the plug...lol. So i just got a new one from NAPA. Cleaned the connector and put the new one in...works like a champ. Wanted to test the old one but i broke it and couldnt...oh well.

 

[typ4]

they have an over current fuse /resistor thing that blows in the resistor pack.when the motor goes weak and then you only have high.

 

[icanfixall]

From What Russ posted above it may be time to replace the possible weak motor..

 

[Optikalillushun]

I took the blower out n cleaned it up...spun freely with a very slight drag. Now it works great but ill keep an eye on it. Thankfully both (resistor block and blower) are right there in the open.

I also cleaned out the evap/blower box as it had some stuff in it.