Posted: 6/20/2009 9:40:23 AM EDT
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My central AC fan won't quit running. The outside unit kicks in and the house cools off fine but the fan won't stop running until I turn the power off to the fan. I have a Lennox Pulse 21 furnace model G21Q3-80-3 The outside unit is a Lennox HD25-261-1P I have replaced the thermostat today after following a troubleshooting guide from here http://www.inspect-ny.com/aircond/aircond15e.htm#ACNoStart2 What else do I check before I call for professional help or start hitting things with a hammer, the last part was the wife's' idea |
| If the relay is on the circuit board you gonna have to buy a whole new board.....taking power completely off the system and ohm the relay it should show open if not your contacts in the relay are stuck closed...I just looked over the info on your system and you have a pulse furnace they are notorious for heat exchanger failure so get yours checked every year and get CO detectors nothing like going to sleep and never waking up.. |
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Quoted:
OK, am I looking for the relays on the fan motor or on a circuit board? Should I be taking pictures? pics help. the relay will be controlled by the circuit board assy. It will be seperate from the fan and the board trace out the wires from the fan on back and this will lead you to the relay. |
| Do you have any means to an ohm meter if so check on the relay com. to blue (should be the hi speed fan) make sure you remove the wire from the relay or you'll get a false reading com. should be white thats the other leg of power...one leg hot to the motor all the time and the other leg is the speed on the motor low for heat and hi for cooling, you have to remove the wires from the relay and ohm the contacts cause if you don't you'll ohm thru the motor and get a false reading...and it's really hard telling that a storm could cause this you at least have the inside fan working and that's a good thing you can buy some time into looking for a replacement board...Good Luck!! |
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Quoted: Quoted: I'd like to thank you guys for your help, it's working as it should now. What was wrong with it? It must have been a stuck relay. I took a screwdriver to tap the top of the relays and after the AC caught up cooling the house the fan shut off as it should. It's been working normally ever since. |