Hi, I have an older gas Furnace (8 yrs)? And it seems to run fine when we first turn it on via the Thermostat (ie, turn on, set temp to... ). Warm air blows out upon initial startup and maintains this heat up until the desired settings.

However as the hours and day goes, on, the thermostat of course, turns on the furnace again if the temperature falls below the set desired setting. When this happens, the air is normally cool or sometimes even cold, ---- and of course, if we're away for awhile, the house is actually colder than normal with the furnace running constantly blowing cold air.

We can usually fix this , but turning off the thermostat, waiting 10 minutes or so, and then turning it on. But ideally we'd like to live with a normal automated system :)

I'm willing and ready to bring in professional help, but was wondering if any experts on this board could provide some insight - maybe it is a quick fix?

Thanks

S

Change your filter and clean your drain. It could also be a problem with the t-stat

Brand/model#? Check status LED on furnace, if present, when this occurs.

Hi

We've changed the filter a few times already and the problem still appears. Here are some pictures of our furnace. Thanks in advance...

What do you mean by drain?

Pic #2 (yours), top-center shows the flame sensor. Remove & clean.

We've been going through this too and I've found a number of things that it could be, but after a furnace check up (for which they found nothing, but did eventually clean our sensor like the last poster suggests) and another service call yesterday where the most he did was blow out the drain and said it did seem a little clogged, it seems to be working normally today. (fingers crossed) I would definitely check the drain. The sensor is always a good thing to clean, but when we repeatedly had that with our old furnace, it just never came on until it was cleaned, whereas this problem was the cold air blowing like you suggest. If it starts acting up again, our next course of action is to have the blue ignition box replaced. I had found that a similar furnace to ours (Lennox) had the same problem and that was their solution. I asked about that and the tech tested it and did find it wasn't doing exactly what it should. However, with it working for now, we are waiting since the $75 service call is cheaper than the $250+ part replacement ($175 for the part and $75 service call). Good luck.

Well, our furnace started blowing cold again, so I guess the part replacement is necessary. It is reassuring we are not the only people going through this.