I have a Trane XV80 two stage furnace. While on vacation the house sitter called and reported that the house temp had fallen to 34-degrees. He told me that the thermostat would not allow him to set a temp above 32-degrees. The thermostat is a White-Rogers 1F80-51 programmable Electronic Digital model. The house sitter also notified me that the furnace LED was flashing a sequence of four flashes. I called the furnace company that installed this furnace and thermostat to respond to my house. At the end of the service call they charged my account for a new thermostat ($229), a new fan high limit switch ($307) and a new motor control module ($577) with the service call charges, tax, etc. the total was $1539. I instructed them to leave the old parts. When I returned home I put new batteries into the thermostat and it appeared to be working. The old thermostat was put back into service. When I confronted the owner he refunded my money for the new thermostat. There came a time when I suspected that the high limit switch may not be bad. I tested the high limit switch with an ohm meter and a heat source and found it to be working properly. I put the supposedly broken limit switch back into operation and it has been working flawlessly since May 1. The owner of the furnace company is refusing to refund my money for the switch informing me his tech found it bad at the time of the service call. I am going to take this company to small claims court but I need some help here. The house sitter swears that the tech could not make the furnace fire until he replaced the high limit switch. Then when the blower did not start the motor module was replaced. My questions: (1) Did the tech need to clear the high limit fault by following the Trane instructions to turn the power on-off twice within 30 seconds? (2) Would the fault have cleared if the tech turned off the power and replaced the high limit switch? My thoughts are the tech didn't clear the fault properly and that is why the furnace didn't ignite, but when he R&R the high limit switch the fault was cleared. I believe that the motor module failed causing the furnace to exceed the 190 degrees limit, tripping the thermal limit switch (Fan high limit), causing the furnace to lockout with the error code.

Bump