My furnace tries to start, the blue flames come out but then it just stops. It continually cycles like this every 30 seconds. It blows cold air. I have to turn it off for a few minutes and when I turn it back it on it will ignite and I will get warm air. When I turn it back on the red light blinks 7 times, goes dark, and blinks 7 times again before staying a steady red. The same thing happened last year and the guy told us the filter was dirty and it was nothing. In addition to the question of what the 7 blinks mean, I am wondering if companies manufacture their furnaces this way so that you have to place a service call at least once a year?

Hi Cesarina. Are you sure the last tech said it was a dirty filter, or was it a dirty flame senser? Either way, it sure sounds like a dirty flame senser this time. Very common, and easy to fix yourself. I would suggest having a tech in one more time, but this time be there to watch. Ask him what he is doing, and how to clean the flame senser. A good tech will be happy to show you the basics of the furnace.

As far as the manufacturer making it so you have to have a service call every year, no. The diagnostics light is actually to make trouble shooting easier. If you have the install manual, or homeowners manual, you can read through it and actually find how to fix many problems yourself.

If you know where the flame senser is located, remove it, clean it with steel wool or fine sand paper and put it back in. This should get you back in steady heat.