I'm a homeowner with a ten year old ClimateMaster geothermal heat pump. I decided to try a new, more local, company to service my unit this year. The technician, who seemed very knowledgeable, showed me some areas that were discolored on the circuit boards inside the unit, which he said were for the compressors. He said those discolored areas indicated the diodes were overheating, which he said happens a lot, but could cause them to fail. He said I should consider replacing one or both boards. No one else has ever mentioned this before. I'm not an electrician, but I do know that diodes tend to heat up, so I'm thinking this might really be normal. I'd appreciate any input on this since I don't want to have my heat pump go out this winter but also don't want to spend money on something that's not necessary. The discoloration is sort of coffee colored. Definitely not charred, but darker than the rest of the board, and located right around the electrical component on each board that he said was the diode.

Thanks for your advice.