I have no 4 (high speed) on my blower motor. I have tested the switch, wires, relay and motor and every thing is fine. I am stumped. Any ideas would be appreciated

 

Please provide your vehicle information with every tech question you post. It saves those of us willing to help a lot of time.

Regardless of whether you have manual or automatic climate controls, the HVAC fuse (30A) in the underhood fuse box controls high speed operation through the blower motor relay.

 

Sorry about that. It's a 2000 blazer LS 4x4 with auto transmission. I checked the fuse and it looked good but I changed it any ways. I have power to the blower motor when it is on high but for some reason the motor is not working. The motor works fine on 1, 2 and 3. No funny noises. When I lost high over a year ago it almost sounded like it was being throttled. It would loose speed and pick back up.

 

... Ok.. Check the wiring between the HVAC (30A) fuse and the relay then...