Night Hawk

Hey guys I have a question for you regarding my digital climate control head unit on my 88 GTA with a digital dash.

Last year the climate control operated properly, but every so often the fan would cut out and the amber light indicating the fan speed would fade away to nothing. The weird part was that every other part of the climate control head unit was functioning properly and you could here the ducts change whenever moving to heater/vent. Now this didn't always happen, just while I was driving around [smooth paved roads] and usaully I just keep on pressing the fan speed buttons and it would usaully come back to life, but it kept on getting worse and occuring more frequently.

Currently the is no response from the fan and there are no amber lights on the fan speed indicator, although the climate control is operating properly. I have tried hot wiring the fan and is spins like crazy. I have replaced the fan relay and the transistor. Today I pulled the head unit out [harness' still attached with key on] and with a test light probed the harness'. There is power going into the head unit's man harness, but there is no power either coming in nor coming out of the harness connected directly to the fan speed control area of the head unit.

I guess the question I ask is whether or not I need a new head unit or is there another way I can go about this.