I recently was called, on saturday, to a customer who's furnace was not working. He explained that someone else had made repairs to the blower motor but now the furnace was shutting off on an entirely different code.
Upon arrival I found the furnace off and a trouble code was being flashed on the control board. This code indicated that the furnace was overheating. I performed all the customary checks and cleaned the Flame Sensing Rod (FSR) and observed the proper operation of all components. My diagnosis was that the blower fan was not running fast enough to move enough air over the heat exchanger and keep the furnace from overheating. After inspecting the blower motor I found that the module that controls the motor speed was not, yes you guessed it, the Original Equipment Manufacturer (OEM.)
Am I saying that you should only use OEM repair parts...... No not at all. What I'm saying is that you should use a company that knows when a OEM part is best and when its not as critical.
To end the story Valentine Mechanical Services (VMS) was able to tell the customer exactly what was necessary to repair the furnace. The customer relayed this information to the previous repair company and they returned and installed an OEM module. The furnace is repaired at this time.