I have a 1987 carrier furnace. The problem is that the blower never turns off- it runs constantly regardless if trermostat setting. I suspect the control board relay is bad - is there anything else to check? Where can I get a new control board or relay?
Note: the contacts on the relay were burnt pretty badly - I cleaned them and replaced the board...it worked for a few cycles then started to run constantly again.
There are a couple of possibilities.
1.) The relay is stuck on at the control board.
2.) The thermostat wiring , the green wire and red wire may be touching each other, to disprove that go to the circuit board an disconnect the green wire it should be landed on the G terminal. If that doesn't shut it off then you have a bad relay on the board.
So can the relay be replaced? Where can I get one?
What about the board - Where can I get a new board if needed?
Any good reliable web stores?
I'm not aware of any online stores that carry Carrier parts and unfortunately the relay can not be replaced you would need to replace the circuit board. Did you try taking the green wire off of the terminal on the circuit board ?
Hold on before you buy one. Is this a red circuit board ?
I'm wondering how you were able to clean the contacts in your original post. .