I thought that I would post here after being a long time reader on these forums. Last night we turned on the heat at the thermostat, and noticed the house colder after a hour. Thermostat indicated heating, but nothing coming out the vent. Furnace diag indicator light showed 3 flashes - low fire pressure switch. There was no vacuum across the switch because the inducer motor was not running. I checked for voltage at the motor and at the PCB output for both high and low 120v. Nothing. Checked the 120v side of the transformer mounted at the bottom of the controller board. There was 120v there. When I flip the switch to allow power to the furnace, I hear a single click from the controller board area. Is the the relay attempting to close? Or maybe closing and opening again. Would there be a diode between the relay and inducer motor? I'm uncertain as to how to check for a defective relay without a bypass point. The unit is 7 years old and has been cleaned every year. Goodman is not honoring the 10 year warranty they promised because they said that they never received the warranty card that WAS sent in. We purchased the Goodman furnace and Rheem tankless at the same time. Rheem apparently received the registration and has since honored their warranty, Goodman conveniently did not. Is there anything else that I can check for before buying a replacement board? Are relays a common fault on furnace controller boards? If it was gas valves or burners, I wouldn't touch it, but a PCB replacement seems simple enough if that's indeed what it is. As long as I match up the DIP switches. The furnace is a GMV95 and the PCB is a PCBBF106 that has been succeeded by a PCBBF107S. Local installer quoted me $700 parts and labour. Whirlpool has the replacement board for $160. I like to learn, but also like to save money where I can. Thanks in advance... B

I have a forced hot air system that's about 10 years old. Worked fine last year. Before this summer, I had it upgraded for central AC. The AC system worked fine for the season, but now when we put the heat on, there is a noise that sounds like the blower blade hitting something. I don't understand how the cold air can be blown through the house fine, but when the heat comes on there's this loud banging. Do the AC and heat use different blowers to push the air through the house? Is there a common screw-up that can lead to the heat blower hitting something after the system is upgraded for AC? Thanks in advance.