Bryant Plus 80 gas furnace. All the cycles seem to work normally - resistive igniter heats up, burners fire, all 5 have nice blue flame, chamber heats up, main fan turns on, burner turns off, fan runs a few more mins (about 3:30 total). However... its running very often and not keeping the house warm (peaked around 65F inside, its about 30F outside). This has NEVER been a problem. It feels like the temp at the vents is not very hot, even the ones that are right above the furnace. Filter is clean, I changed it about 2 weeks ago. Admittedly the old one was very dirty - went too long. I also just (few days ago) started using the whole-house humidifier. We never have before, but it was getting just unbearably dry. I am suspicious the limit switch is not working properly, possibly affected by the buildup up dust and now addition of moisture. It clearly hasn't "failed" completely b/c it still opens and closes, but I suspect the bimetallic sensor isn't completely cycling any more... such that it kicks off at maybe 160 instead of 190 as intended (its a 190-40). So after all that, here are my questions: 1 - is that a reasonable possibility? Given the cost of a new switch it seems an easy thing to try. I pulled it out, it "looks" OK, a little dusty but thats it. Cleaning didn't do anything but I didn't expect it to. 2 - more importantly... my luck is that this is Saturday, and a holiday weekend. All local HVAC places are closed (only a few here will sell to DIYers anyway... ergh). Is there any kind of trick or bypass I can do to get me through to Monday? Listening to the thing run constantly, I'm hearing dollar bills getting sucked right back down the registers.... I considered wrapping a little tape around the sensor to insulate it a little, hoping to raise the upper temp at which it would trip. But that seems like its pushing the edge of safety, I don;t want it to run indefinitely and cook my furnace! :eek:

Having an issue with a Goodman furnace. The draft inducer turns on with the thermostat calling for heat. The inducer will run for mere seconds, turn off, then cycle all over again immediately. This will go on for hours, with no ignition. The red code light goes out when the inducer kicks off. Audible clicks can be heard when the inducer comes on and goes off. This seems to happen on the coldest days. I shut off the furnace by the A/C switch on the side for fear the system will self destruct from failed attempts to start. I'll turn it on again after several hours and the cycle will begin again, with ignition finally happening after within 30 minutes to many hours later. It will then run for a few days until it goes back into the no start mode. The original installer is no longer in the business. He referred me to the "best guy around" to fix it. There have been two service calls so far with attempts at resolution. Service call #1. He comes over during a period where the furnace is not running. He proclaims the original installer wired the thermostat wrong. He changes some wiring. Heater starts after being off for days and all is well temporarily. Service call #2 (one month later). He comes over after furnace is running again following no-start period of 1 day. He says original installer didn't put enough return vents in the rooms (5- 6" returns) so he cuts a hole in the side of the heater in the basement and puts a filter there. Theory is that it is "hitting the high limit" because of not enough return air. He doesn't seem to understand that the inducer is kicking off, not the blower. Now there is colder air coming out of the vents because heater is sucking 45 degree air from the unheated basement. The heater failed to start 40 minutes after he left. When I explain to other service companies what the problem is and tell them who I've had attempt to fix the problem, the reply is that if he (best guy in town) can't fix it, there is nothing we can do. So here I am on this board. I have mechanical skills and electrical skills, but no knowledge of how the heater works. The manual says that the after 3 failed attempts, protection mode kicks in and further attempts are delayed. This is not happening. The inducer will come on/go off 50 times an hour with no break. No stored codes. As stated, the red light on the board goes out after seconds of inducer starting and kicking off. About 1 year after the furnace was installed I noticed a change in the sound pitch of the inducer. It now sounds like an old fashioned air raid siren spinning up. There seems to be adequate air flow out the vent, but I suspect I may be looking to replace the blower in the future. I have checked the air inlet and outlet of the system and it is clear. There are grids on the ends of the pipes. Seeking guidance at a resolution. Thanks in advance for all imput! ---------------------------- Goodman GMH95 Series installed 3 years ago to replace original boiler system installed in 1949. All new ductwork, returns, gas line installed, thermostat, A/C unit put in at the same time. 1. Southern NJ, Temp. 35 F 2. Poorly insulated 1900 Sq ft brick rancer, 1949 3. Goodman GMH95 series, 3 years old. 4. Natural Gas 5. n/a 6. n/a 7. LuxPro WXPSP511LCA Thermostat