I came across this site while trying to find out some information on my furnace. So far from what I've seen, it's very informative and helpful. I read the rule about DIY's and the questions/answers I may receive. I'm really not asking how to fix my furnace so much as what's wrong with. I can understand a professional repairing it if it was needed, but if it's just a $10 switch or something, would that be ok for me to do?
Onto my problem(s):
My furnace is a Goodman GMP100-4. I've owned the home for almost 4 years. The home is an 1100 sf ranch style with a full basement. The basement is not finished and is sitting at bare walls and floor. The furnace is approximately located in the middle of the basement against the back-side wall of the house. There are 4 cold-air returns; the main one in the hallway, 1 in each bedroom, and 1 in the basement. There are 2 vents in the basement that I currently have foil taped off since it's not needed down there.
When the furnace kicks on, the vent fan spins up fine. When the flame starts, it makes some gurgle/burgle noises and then lights up smooth. While the furnace is running fine, the flame cuts off and the vent fan slows down, but the blower continues to run. Then suddenly, it kicks back on and keeps doing it's thing. I listened on the thermostat and it's not being satisfied by the furnace. Meaning it's not getting the house to the set temp. before cutting off, hence it cuts back on and runs longer. For a short time, the vent fan would kick on and the furnace would never light. But after throttling the on/off switch a few times, that stopped.
My FIL has helped on this project. He's a licensed firefighter and home inspector, I know this doesn't qualify him to do this, but he's not ignorant of the dangers/consequences. We've cleaned the sensors and that didn't help any. We recently replaced the hot water heater and since it was moved to the other side of the furnace, we re-did all the vent duct work. Everything passed the inspection from the inspector and we were actually complimented on how well we did and made it look. I replace the filter's regularly and yes they are dirty but nothing irregular. What could the problem be? My FIL thinks it may be the fan limit switch. I spoke with a Goodman parts distributor and he has the switch as well as an air pressure switch that the tech said it might be. I was going to try those two before moving on to bigger things. My goal was to remove the simple things from the equation before calling in a professional.
Any information will be greatly appreciated. Hopefully I worded this correctly to not get it locked.
Thanks in advance & be gentle, I'm new