Bryant Furnace

[pumbaa68]

I have a Bryant Furnace model # 310AAv066110, it starts up normal. After 5 minutes of blowing warm air it starts blowing cold air, it flashes 33 and shuts down. 3-5 minutes later it starts up normal and goes through the same procedure. It does it all day long. I changed the filter, by-passed the thermostat, and cleaned the flame sensor. Any help would be appreciated. Thanks

[hvacwiz]

have you checked to make sure your condensate trap is not plugged.

[pumbaa68]

No, now the dumb question were is it?

[hvacwiz]

I should have asked you if it is a 80% or 90% furnace. Only a 90% furnace will have a condensate trap, and It should be located in the blower section.

[pumbaa68]

Mine is the 80%. Thanks

[jnaas2]

Does it say on the furnance what code 33 stands for

[pumbaa68]

"code 33" - "LIMIT OR FLAME ROLLOUT SWITCH IS OPEN
If limit switch is open longer than 3 minutes code changes to code NO. 13
Check for:
a)Blower motor failure- Blower works
b)motor start capacitor ????
c)open flame rollout switch Tested 24.85 Volts
d)inadequate combustion air supply (flame rollout switch only)
e)dirty air filter Replaced
f)defective limit switch or connections Tested 24.60
g)loose blower wheel" Not

[jnaas2]

If you have lived there for a while and this just started to act up its from low air flow across the heat exchanger. When it hits the temperature limit it shuts the burner off until it cools down then will start the burners again. This can be caused by vents being shut to rooms in the attempt to save on heating bills or from a dirty blower wheel or filter. The fan moter has different speeds and the blower speed may need to be changed but first make sure everything is clean and working right first

[pumbaa68]

I have lived in the house since 01/2004, it was a new build.
Checked blower wheel and it is clean now.
So now I lost heat completely, it flashes 31 now.

[pumbaa68]

Turned out to be a pressure switch and a limit switch. But I have heat now.