Ac/heater fan only blows on low and medium speeds.

[PhotoDoctor]

My 1994 4.0 jeeps ac/heater fan only blows on low and medium - High no longer works.

I'll bet there is a post here somewhere about the issue but I have not found one.

Any thoughts (The good new Is medium still blows a lot of air but I'd rather be proactive on fixing it)

Thanks

[4.3LXJ]

There are a couple of things I would check right off. One is the switch in the dash selector. There is a lot of current that goes through that switch and they can burn the contacts or terminals out. The other is the ballast resistor located on the HVAC housing under the glove box. They can burn out too.