I have a gas heat unit.. the piolt light is lit and the heat is turned on yet i am gettin cold air out of my vents.. sometimes it cold air then sometimes it works just fine for a day or 2 then will blow out cold air/
I'm a roofer by trade by sounds like a thermostat problem. the one at dads rental propriety used to do that and we found that the fan was running all the time. you should call HVAC certified tech. to be safe sir. plugged (pilot) orifice is a common problem (gas line)
Hello jr_38320: The flame sensor may be corroded or non-functional. Turn the unit off, and remove the flame sensor. Clean it up with sandpaper then replace, inspect the wires connecting the flame sensor to the unit. Turn the unit back on, and turn the thermostat to call for heat. With a standing pilot, when the thermostat calls for heat, it energizes the gas valve, and fuels the burners. When the heat exchanger reaches temperature, the fan switch closes and brings on the circulating air. You will also want to very carefully inspect the heat exchanger for holes. The gas pressure from the gas valve may be too high, causing 'over-firing' and opening the high-temperature limit safety switch. If the heat exchanger gets too hot, it shuts off the gas valve, but leaves the blower running. To test the gas pressure, you will need a manometer, but a simple test is to get an accurate thermometer (from the cooking isle at your department store). Put the thermometer probe near the limit switch, and see how hot it gets. If it gets too hot and the flame cuts out, this is your problem. You say that it takes five minutes before the fan comes on, this is rather long. It should only take 45 to 60 seconds for the heat exchanger to reach temp. It may be the heat sensor switch itself has worn out. It may also be the motor. When running, is the motor 'hot' to the touch (120* or hotter?). It could be a capacitor or the bearings. It is best to have a trained technician inspect the unit and make any adjustments or repairs.
