coppercutlass

My funrnace has been on the fritz so to speak. The ignitor comes on the the flames come on and once the blower motor comes on they shut off. Now here is the weird part if i shut it off for maybe 4 hours and turn it back on it will heat the house back up no problem. My settings on the t stat are fine hourly wise . It has to be something simple. I replaced the filter it looks clean in there. I read the manual and the only 2 things that make sense on what it could be is the pressure switch or the flame roll out switch. But i need to find out if those are bad but the manual sucks at explaining how to check things and it just tells me to call an hvac guy. I have a multi meter but i have no guides on which to go by. I have all the model info . Any help is appreciated.

Allan R

Get a hold of Scot (GAOldsman) I think he knows a lot about this stuff.

coppercutlass

Thanks. Im trying to get this fixed so my brother in law does not have to drive here to fix it.

firefrost gold

check the clear tube at bottom it will fill up with junk and do what you are saying yours is.

Lady72nRob71

Is there an LED flashing a trouble code?
Is it a truely intermittant issue and not predictable when it will occure?
About 15 years ago I found cold solder joints on a control board that caused weird shutdowns.

coppercutlass

Cool where is it located. I have the ignitor then the flutes or vents whatever they are called that blow the flames then there is a tube behing those.

coppercutlass

The led light stop blinking when i shut it off totally from the power source. It was blinkin but in a non rythmic patter that i would call diagnostic patter. It just blinked. It is predictable. It will run enough to heat the house., then not blow hot heat anymore. I let i sit shut off for about 4 hrs. plus then it blows hot again

coppercutlass

Ok I went back down beer in hand lol. I dont see a clear tube . But the lights arr blinkin again. Green and red blink . green comes on comes of and red comes on and off in a cop car like pattern back to back if that makes sense.

w31man

Check the flame sensor, its a bare metal sometimes straight sometimes L shaped should be sticking in the flame soewhere. Take it out and clean it with sand cloth. I have seen this problem tons of times

Greg

MDchanic

Okay, as with automotive questions, we need more information before we can begin to give you intelligent answers.

• What sort of fuel does this system use? Oil? Natural gas? Propane? Kerosene?
• What sort of a furnace is it? Forced hot water? Forced hot air? Steam?
• What sort of ignitor is it? A red-hot coil or a spark plug?
• What do you mean by "blower motor?" The motor that blows warm air through the house, or the motor that blows combustion air into the burner?
• What filter did you replace? Filter for house air, or oil filter?
• What pressure switch do you mean? Fuel pressure? Household heated air pressure differential? Combustion intake air pressure differential?
• What are the make, model, and year of the system?

- Eric

coppercutlass

I think i fixed it. Its a gas furnace. I replaced the air filter for the house. It has a red hot ignitor, It's the blower that blows air into the house, I think im talking about the heated air pressure, some one mentioned gunked up . I remember my dad would always vacuum the furnace every year. I think i now know why. Im a new house owner so kinda like a deer in the headlights. I just hope this isn't one of those intervals it goes into. I wont get into make model and year until i really need to get into it. sorry eric. It's a newer maytag i think 2005 or 2007. Btw all i did was grab my shop vac. with some .5 aluminum tubing left over from my fuel system duct taped to the shop vac. tube and sucked whatever was inside. I turned it on and i had heat again. I hope this does the trick.

MDchanic

I'm pretty good with oil, but less experienced with gas, and know nothing about the kind of controls you'll find in a 2000s model anything.

So I'll just leave this one to the experts...

Good luck! You'll get it.

- Eric

edit: If there is a pressure differential switch that tells the unit that the fan is working, so that it can keep the gas on, that switch could be screwed up - you can test its basic function by removing the hose and blowing into it (or sucking), and seeing whether your meter shows the switch closing (or opening). If not, you can try it with the switch disconnected, and if that doesn't work, try it again with the switch terminals shorted. If one of those fixes it, you need a new pressure switch.

Lady72nRob71

Hope you got it fixed...
I sure liked the old units that an old fashoned thermocouple and two thermostatic switches on the heat exchanger. The ones we had never had problems until the HE's rusted out after 20 years...

coppercutlass

Seems to be working good. The house warmed up pretty fast. Much faster than the last few day's it shut off and turned on again 2 times since blowing hot air every time. It's working much better than it has the last week.

fitter bill

usually a rollout switch located down toward the burner is a fuseable link or manual reset with a red button on it . if u got the furnace to fire that rules them out . if your furnace is newer and high efficiency (with pvc flue & intake ) i would check the intake screen for dirt & leaves with wind we had around here . plugged screen wont let the pressure switch make .look on the inside of the blower door for the diagnostic codes to tell what it failed on.

coppercutlass

It started acting up the other week with all the rain we had. I vacuumed it and it has kicked on a few times already with heat. The intake screen looked good. If it craps out again i"ll look on the inside of the blower door for the codes thanks that is really good to know. Now is the intake screen where the filter goes ?

fitter bill

if it is high efficiency i would check right at the furnace you can usually loosen the connection of the upper pipe at the furnace and move it aside to access the screen just make sure its the intake .

coppercutlass

It works guys. Thanks for all of the help. It stayed on all night ad has not shut off since.

69442C

Glad it's functional again but you may want to have a qualified technician check it out for you. Keep in mind that today's heating equipment is nothing like the older systems so what was typical for maintenance years ago may not be what is done today. Maybe it was dirt or maybe the gremlin is just taking a nap and will decide to wake up when it's zero degrees outside. Also being natural gas, you need to know what you are doing so you don't risk life or property. Those flashing lights on the board are trouble codes and are very helpful in diagnosing a problem.

I'm assuming you have a closed combustion chamber in your furnace and that would be evident if you have 2 pipes that run outside? One is air intake, one is exhaust. Any debris in those pipes can cause an issue such as leaves, birds nests or rodents. If this sounds like your system, here is a typical process the heater goes through to function. When the t-stat (which typically operates at 24 volts) calls for heat, there is an inducer motor (small blower motor) that will begin to run and it brings in the fresh air and blows out the exhaust. This inducer motor will create a small positive pressure (inches of water column or fraction of a PSI) that is seen by a pressure switch. This inducer motor start-up can last for 20-30 seconds. Once the controls are satisfied that this system is functional, meaning the pressure swicth closed and remains closed, it will engage the ignitor (heated plate, glow element or whatever is used) and some units have an electronic eye that is looking for the glow. Once that is seen, the controls will send power to the coil for the gas valve so gas can be fed into the conbustion chamber through the burners and the gas will light. There is a electronic eye that will look for that flame and if all is OK, the burner will continue to heat the chamber. Once the chamber gets to the correct temp, the main blower motor will start and air will blow across the chamber and out into the duct work.

It's possible dirt was on one of the electronic eyes and was shutting down the solenoid which caused the flame to go out. Or, maybe there is another issue that is still there that may crop up again. The controls are very complex and there isn't a way to jumper out a defective switch because the system will know that was done. It's all in the name of safety. I had a similar problem like you described a few years ago and what was discovered was the main control board was bad. When the power was sent to the coil on the gas valve (24VAC) , the small load from the coil would cause a connection on the board to open up, breaking the 24 VAC circuit and the solenoid would close and put out the flame.

Think about having a technician check it over and be safe.

Brian

coppercutlass

My brother in law is an hvac tech. He is coming over next week i have to fix his car so he is just going to look over it while i do that.