Air Conditioning - Diamond York 80 - shutting off....

Hey DIYers!

Having an issue with my Diamond York 80 furnace. Recently it began shutting off at night, and when we wake up in the morning the house is freezing! When this occurs, I go down to the furnace and notice the red "service/error" light is always illuminated (just on, no flashes or anything). I turn the furnace OFF using the master power switch on the side of the furnace, wait a couple seconds, turn it back on and it turns back on just fine (vent motor, igniter glows, gas ignites, blower turns on, everything OK).

This has been happening for about 2-3 weeks, but there was a 3-4 day period where I never had to re-cycle the master power switch. And it never seems to occur during the day. Strange!

This morning, I did notice a first - when I turned the "master" power switch off and then on, it cycled through the steps - vent motor started, igniter glowed brightly, but the gas didn't ignite. After a couple seconds it shut down and the red light illuminated (no flashes, just ON). I recycled the master power switch and it turned on just fine. I'm wondering if this is what's happening in the middle of the night.

Any ideas? Things I should check/replace?

I am by no means a home repair technician, nor an electronics engineer but I'm usually capable of repairing most anything in the house. I'd really like to spend money on the holidays/gifts than on my furnace!!! ;)

Thanks!!!!

You really need a couple of specialized tools to properly service a gas furnace. If you want to try something you might just go ahead and replace the thermocouple first and see what happens. If your furnace has not been serviced for a while it would probably be money well spent to have a proper service done. Low airflow due to a dirty filter or blocked return-supply/Low gas pressure/Dirty pilot orfice/Blocked vent/Bad or dirty thermocouple/Bad gas valve/Bad gas valve control/Cracked heat exchanger are a few of the things that can happen to a gas furnace. You might have someone come out and have them go thru your unit while you are there and you can watch and take notes. Then maybe from that day forward you could do your own service if you invest in some tools. Every time I hear about someone inexperienced working on a gas system it reminds me of my neighbor that blew his houseboat to smithereens after he worked on the gas furnace on it BBBBBOOOOOOMMMMM These furnaces have lots of safety systems and when properly serviced are considered by most people to be safe. I personally would not have one in my house. When you cycle the master power switch you need to keep in mind that you are overriding a safety feature and that is NOT RECOMMENDED.