Nando,
I am an electrical engineer and have repaired my circuit boards and understand the system fairly well. With the information you have given in your original post I am fairly certain the problem is not with the thermostat. That leaves the board and its components and the motor itself. My experience has been the circuit board is not well designed and is boarder line for switching the current loads that it is required to control. I have replaced the switching relays and repaired circuit traces that were burned with additional wires and solder. It is easy with my background, but not so easy to detail in a post. I was able to find the relays that were used on the board on the internet and obtain them at a very reasonable price. My A/C manual included a schematic and wiring diagram for the circuit boards and well as an english language description of the proper sequence of operations. Should you desire to attempt to troubleshoot the board and repair on your own I would be glad to try and assist. Good luck. Just remember if you can use a voltmeter you would be able to determine if the board is bad, or the motor has the high speed winding burned open. Russ
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