1.Thermostat activates the centrifugal chamber air pump. 2.If green light on control panel lights up, furnace will operate normally. 3.If green light does not come on, centrifugal air pump will run for hours. There is no click or apparent attempt to initiate gas valve or ignitor. 4.Simply turning off furnace at door switch and back on will always return furnace to normal heating cycle. Turning down thermostat to shut off furnace will also return furnace to normal operating cycle. Furnace will do this at erratic times, sometimes go days, weeks between malfunctions. Have had installed; 2 control boards, 2 limiter switches, 1 ignitor, 2 fan limiter switches. Pressure switch was bypassed by a previous HVAC tech in an attempt to solve this problem. What about a shutdown from the previous heating cycle that resets with power on/off, but does not reset?
It sound like the limit switch is shutting off and not coming back in to play .
Testimonial: "A previous HVAC tech removed the limit switch and wired it 'hot'with no change."
SOURCE: 1993 goodman status light 4 times blinking
I have a goodman GMP075-3 that won't turn on. I think it is the pressure switch since I do not have a vent blockage. What is a venter and where can I find it??
SOURCE: Goodman furnace GMPN080-4 Getting 4 RED blinks/Open Limit Swtch
You have a limit switch located in the furnace (a little bigger than a dime and located near the center of the front panel, sometimes the switch is mounted to a small fiberglass board) . There will be two wires going to it. They sometimes trip so often that they fail to automatically reset(due to dirty filters or undersized ductwork). You can SHUT OFF POWER TO THE FURNACE, then remove the two screws holding the switch in the furnace, pull the switch out of the furnace and tap on it and wipe it off.
The switch may work a few more times but should be replaced with the same size and type. You will see some rating printed on the switch somewhere. Write down all the numbers and get a replacemet from a furnace/AC supply house. If you have a meter and know how to use it you could check the switch for continuity.
Sometimes just a tap on the switch will get it going. There will also be a couple of rollout switches that could be tripped. They have little buttons on them to reset them. If they trip it may have other issues to be solved.
Hope this helps!
Matt
SOURCE: goodman gmnt100-4b wont ignite
I had the same problem. I had to remove a return air duct filter that i had installed and it worked just fine. The system needs plenty of air flow to operate.
SOURCE: furnace wont start. heil gas furnace. on initial
Yes, inspect the air intake, exhaust pipe, filter and condensate piping for blockage or moisture. Also check for a hole in the hose that goes from the small exhaust blower to the pressure switch or a bad connection on the switch or control board. You may be able to temporalily jump the switch for diagnostic purposes only.
SOURCE: Coleman furnace -- fan runs, ingniter won't light,
My furnace did not have a reset switch on that particular limiter. I unpugged the switch, it had 2 wires, waited 15 seconds or so and then plugged it back in . Turned the furnace back on and the limiter reset itself.
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