[ioeuropa]

Hey all,

I have an an American Standard Freedom 80 two stage furnace with a honeywell thermostat. I have owned the house for 5 years. Last year the furnace started working intermittantly. This year it doesn't. This year when I turned the heat on, the thermostat clicks and it's green light comes on, and sends a call for heat which is indicated by the fast flashing red light on the inside computer in the furnace. The exhaust fan comes on, then the ignitor heats up bright white for about 10 to 15 seconds, but I get no flame. After the third time that the ignitor heats up, the exhaust fan shuts off, and the computer flashes a series of two flashes constantly. The front of the computer says that two flashes indicates "system lockout, check polarity".

So do you think I have a sticking valve?

Any help would be appreciated.

 

[HVAC Doc]

Just curious, did you have any electrical work done last year when it started working intermittantly such as breakers, main panel, circuit that furnace is on? Most commonly (not always) a stuck/bad gas valve will give an error code of No Flame. If nothing changed electrically, head to the valve (that is after you check and make sure gas is turned on).

 

[ioeuropa]

Nope, no electrical work done. I have also emory clothed the flame sensor to get the crud off and make it nice and clean, and checked the internal heat fuses, they're all about 6 ohms. I just don't want to blow 120 bucks if it's not the valve. And I've read about other guys with the same problem as me, and it was not the valve, but I never found out what their answers were.

 

[HVAC Doc]

Well I would probably recommend a tech to come out and check it and actually diagnose the problem. You could have a polarity issue, a control board issue, or a gas valve issue. Question is how many parts do want to "guess" at and replace in hopes to finding the problem before you spend a bundle changing out a bunch of parts?

 

[ioeuropa]

Furnace fixed

Hey all,

I replaced the valve after I verified that it was getting 28 volts from the computer, now the furnace is working. However, the day before yesterday, the furnace computer cut the valve off for a very short period even though there was a call from the thermostat for heat. The red computer light was blinking three short blinks which says that there is possibly a pressure switch problem. This happened only once that I noticed since I replaced the valve a week ago. It was strange that it happened on the windiest day of the year. I'm thinking it might be the wind acting like a partial blockage in the vent. Then again, it could be another problem which makes the valve cycle on an off alot more than it should and eventually overworking the valve and the igniter. The investigation continues.

Thanks,

Vinny