Goodman pressure switch
In my twilight years, I still try to learn a little every day. Today a Goodman gas furnace less than 2 years old failed to work. It was doing nothing when I got there. I checked the gas and electric supply, all OK. No codes flashing. The 24 volt transformer had the proper output voltage. That was the limit of my knowledge. So I turned off the electricity and called a fellow who installs Goodman. He said that when turned the power back on, the code appeared-- 3 flashes-- bad pressure switch. None in stock locally. Supposedly available tomorrow.
Searching on the computer turns up several posts about this pressure switch. As I have pieced together a supposed understanding, the switch must be open at the moment the inducer fan starts and then it must close-- with every furnace cycle. The furnace will try this cycle 3 times and then shut down. Turning off the power supply and then on again resets the process.
Is this correct?
Seems to me, my idea, not suggested by others, that a simple single pole toggle switch could be substituted for the pressure switch to test the furnace for operation-- to see if all else is OK. The toggle switch would be open and then would be manually closed as the inducer fan gets up to speed. That would run the furnace for one cycle. Is this idea correct?
Do these pressure switches have high failure rates? Would it be wise to have a spare on hand?
The switch is marked 0.7 and the tech tested the pressure on the hose with the fan running and it was about 1.7, over twice the minimum required. Or is the 0.7 a maximum and the 1.7 points to some fault?
Answers for the questions are welcomed and appreciated along with additional suggestions. Those occupants will be cold until tomorrow.