I have a tempstar (ICP) furnace put in when the house builder built the house. Model is N9MPD075F12A2. Installed late 2009. This problem only happens with the furnace not the AC. When calling for heat, the furnace will run 10 – 15 minutes then give me a 4 blink error which is (limit or roll out switch open). flames turn off, inducer finishes it run along with the blower motor. Then the furnace resets and turns on right away again. This may happen 1 – 3 times to reach the desired temperate especially when wanting to raise the temp by 2 or more degrees. I have removed thermostat and hardwired w and r wires with same condition. I have a non pleated filter at the furnace, and a 20x20x4 return filter on the first floor right above the furnace. Honeywell model FC40R1003. These have been replaced and the issue is no better. Two ceiling return grills on the second floor also. I have removed the honeywell return filter and this has still happened.
I have cleaned the flame sensor, no help. There is no rollout of flames out of the heat ex-changer that I can see. The flames stay inside the exchanger when they first light and also when the blower motor turns on. This is a 9o or higher efficiency furnace so I have intake and outtake pipes 2" ID with three 45's and 4' going up to ceiling and 10' across to outside.
Looking for solutions and things to check. Thanks
Best Answer
Thanks guys, I had a pro check it out. The furnace is working fine. He found too much air restriction on the return side, and corrected it. There was too much of a temperature difference between the cold return and the hot side. The heat exchanger was fine.