Question: Why has the furnace started making a knocking noise and smelling like a hair dryer? Two techs have told me circuit board is fine, but the 3rd tech said circuit board is bad. A voltmeter and knowledge of what you're doing with it is important. Check the ignitor. Best wishes to you and yours. If the inside seems dirty, use a soft brush to gently clean the thermostat. Answer: It sounds a lot like a pressure switch. I really appreciate the feedback. This process will repeat until a flame is sensed. What could be the cause of this? I reset it manually from the breaker box. However, the issue might persist, even after you had reset the furnace. What would cause this? When I looked at the temperature on the thermostat it read 61 when it was set at 68. If you do, then the problem is either the gas valve not opening or the gas is off or potentially there is air in the line and it may need bled out. Hi, Dan. It just hummed. The control board has a steady red LED meaning that the control is ok. How should I further troubleshoot my furnace's ignition problem? Remove the cover. The remedy that works 100% of the time: - turn off the switch on the outside of the furnace - wait 30-60 seconds - turn on switch - furnace works fine until the next long idle period. Solid Red and Green Light on Furnace [Reasons and Solutions] If you don't see or hear these things, the furnace will stop the cycle. I took the module off the blower motor. Although you may not want to, you should consider calling a professional HVAC technician. This happens when the pressure switch is stuck in the open position. Question: I smelled burning wires, and then my ten-year-old trane single cycle furnace stopped working. Range should be +/- 10%. Thank you again. I have a Goodman GPG1360140M41AD. Landlord said in spring she will have ducts cleaned.. it is 2 story townhome, furnace is in basement not in same room with washer dryer if that helps. It remained on low flame stage 1. Generally speaking, this means there is a problem either internally within the furnace system or with the thermostat it communicates with. Now furnace works however fan will not turn off and I have to keep recharging my nest with USB every day. It stopped heating my house. Perhaps a burnt out heating element? Keep in mind I cannot guarantee that but these are common failures that have this symptom. have an intertherm electric furnace hooked the power up to it set the thermastate and it was all ready running waiting for it to turn off at th temp i set it but it never shut off and the blow was still running on hight and i could see the coils still glowing red tryed everything to shut it down till i pulls the disconnect over the cartages fuses and it shut down could it be the digital thermastate being faulty? A new module would be best to not only address the fuse but the underlying issue that caused it because I also know that a large majority of the motors never fail, but the modules do. Question: After the furnace has been idle, it frequently (75%) will not provide heat when the thermostat places an order.