Originally Posted by peng teo
Haha..yes it seems like when you guys show up and the problem go away.
It is true...guess what, after he left, the heat reached 65 as set on the thermostate. It stopped. When the room temperature dropped to 62 and I saw thermostate calling for heat -- the HEAT blinking sign. Furnance complete quiet. Well, I called the technician (he said I can call him if it is not working again). He won't believe it. But he asked me to unplug the thermostate and cross wire red and white and see what happen. The moment I took the panel off, the furnance kicked in. But I waited and waited no heat, I crossed red and white wires and hold it as instructed...nothing happened. He suggest I replace the thermostate and see what happen next. Anyway I put everything back, two hours later, heat came on. So now at least I have heat until tomorrow morning and my wife won't kick me out to the garage. I will get a new thermostate at HD to replace it.
It never fails.
Turn the stat to off and jump (or cross as he put it) the W and the R terminal in the furnace at the control board. If heat works normaly when jumping in the furnace, if it comes on each time you jump those wires, then the stat very well could be the problem.
Remember when doing this that the furnace door switch needs to be pushed in to allow power to the control board so jump the terminals with the door switch off and once connected W to R push the door switch in so the unit fires up, if it will. Jumping with power to the board could cause a fuse to blow if you touch metal with your jumper wire so be careful.
So if that works and the furnace starts up then release the door switch to kill power. This way you cut the entire furnace off all at once. If you simply remove the wire witht he door swithc closed ( giving power to the furnace) then the heat will cut off (no flames) but the blower will remain on for a minute or 90 seconds after the flames cut off. This is what it is supposed to do but then you have to wait that 90 seconds to fure it up again.
Whatever you're comfortable with doing in other words.