97 dodge 2500 cummins diesil, fan doesn't work 80 % of the time. wondering if anybody has any ideas. thanks

 

id say your blower motor is on its way out then. or there is a bad connection. do your blend doors move when you change them?

 

Mine was doing the same thing. I ended up replacing the blower, the relay because I was there, and I put a new control switch on. It's been working fine for about a year and a half now.

 

I'd try cleaning the contacts on your control first. It's free and don't take much to do.

 

I had that problem in my jeep. I replaced the controls panel. Problem solved.
Prior to replacing the controls however, I isolated the problem to a bad relay on the panel. I bought a generic relay and "made it fit". Lasted for a little over a year before I had problems again and replaced the controls.

I got it used from Advanced Autoparts.