Carrier Furnace Heating Help

tim smith

Pull tube(s, black tubing about 5/16 diameter rubber, loose one at a time that go from pressure switch to heat x connection and poke out connections on collector box, NOT on pressure switch (round silver device with wires to it). Don't miss where they connect back to! Use like a paper clip or piece of 14 gauge solid wire to clear port. These will get some debris in them and when heat x fills with flue gasses it will nuisance trip on pressure switch. If at all in question of this properly, Don't do it. Call service tech.

wxman

Carrier Furnace Heating Help

I have a carrier 80% furnace and I have recently started experiencing some problems with it. The problem is, sometimes when it calls for heat when it gets to the part where the gas valve opens and releases the gas, it ignites and only stays ignited for about 5 seconds and then it cuts out and starts the cycle all over again. Sometimes it will do this once or twice before the gas stays lit and the blower comes on, other times it will get stuck in this cycle and I have to intervene and turn the thermostat on and off and that seems to kick it out of the bad cycle... and it will either go into a good cycle and heat the house or start the bad one over again.

Only thing that came to my mind was a failing flame sensor, but that doesn't explain why it works some of the time, and why I need to turn the thermostat on and off to get it to work sometimes. I already jumped R and W at the furnace to see if it was the thermostat, but I encountered the problem when I did that too. Maybe you guys can help!

tim smith

Re: Carrier furnace problem

May just be a dirty flame rod or possibly your pressure switch ports are blocking up, combustion fan wheel getting dirty or partial flue obstruction. Lastly, may just be a defective ignition module making intermmittent contact. I would get the little bit of cleaning done first to verify things are clear and clean. Then would really lean towards ignition module. PS we are a carrier service/install dealer. Tim

Tony_23

Ignition systems

Does it employ a hot surface ignitor or is it older, using a 3 wire spark-lit pilot ?

Sounds typical of 3 wire pilots that need cleaning or replacing.

The most assured way of fixing the real problem is calling a heating professional familiar with the Carrier/Bryant line.

wxman

Its a hot surface ignitor. I'm really leaning towards a dirty flame sensor and might take it out today and scrub it with steel wool.

Steve Ebels_3

It's either..........

It's either your flame sensor or possibly the "wings" on the burners. The flame sensor should put out a minimum of 3 micro amps current if you have a meter to test with. Once in a blue moon I'll run into a sensor that doesn't conduct even after it's cleaned and it has to be replaced.

The burners have "wings" that transfer the flame from the first burner, by the ignitor, across to the last, by the flame sensor. Sometimes they'll get crudded up, especially if the furnace is in a laundry or other dirty environment. The only fix to that is remove them and brush them out.

Best to use a stainless brush to clean the sensor and/or the wings because regular steel or sandpaper can leave residue which will eventually cause more problems.