Two years ago I seemed to encounter a similar problem but this time things seem different. Last time I cleaned the flame sensor and things worked just fine...until now. I'm not knowledgeable on this type of stuff but this forum has helped so I'll try to give as much information as I can. About a week ago I noticed my York 90 furnace in my condo continuously running but not providing a to of heat. As I live in Wisconsin this problem will get worse as we get deeper into winter. At first I thought it would be the flame sensor again. It would ignite and I'd here three or four clicks and gas wouldn't stay on. Happened two years ago. Cleaned it off and tried again to no avail. Put thinking about it off to the side as thanksgiving holiday got in way. Started messing with it again, now I run into different issue. Starts up as usual, heating coil turn bright , gas turns on and stays on (sometimes right away,sometimes after a few clicks). Problem now is the heating coil goes out right when gas kicks in so it doesn't blow out any hot air. Runs fine for two to three minutes then gas goes off. Panel blinks red light four times (once doing this test a few times, I saw it do three blinks of red light). I cleaned out the one tube with a straw by blowing and sucking gently. A tad bit of water comes out but nothing that seems out of ordinary. One thing I did notice, I think one of my tubes may have a small hole in it as blowing and sucking caused a very small water drop to build outside tube. One time I had the tube in as normal and just tried squeezing the tube to see if that would help and when gas kicked in, I could feel a whoosh on my hand. Now, is this the root of all my issues? A teensy hole in that tube? Or any other potential issues? If there is any other information you need from me to help me out, just ask and I'll do what I can to help provide you the answer. Thank you .

Just bought my house a few months ago and something isn't quite right about the central heat. It's a natural gas furnace (Kenmore Model #H8MPN100F14B). When the heat is trying to come on, you hear the blower come on first, then after a few seconds it goes off. Wait a few seconds THEN you hear the furnace's pilot light lighting the burner. Then the blower will come on AGAIN, as it's supposed to. Why is the blower coming on first when no air has been heated yet? Any ideas of what's wrong or what to look for? The home was inspected before I purchased it, but the inspector did not find anything wrong with the furnace (it was still warm weather here, when the inspection was completed). Thanks!