Blower Won't shut off on Goodman GHP125-5


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Old 02-09-13, 10:05 PM
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Blower Won't shut off on Goodman GHP125-5

Several weeks ago, the blower on our AC/heating unit would occasionally come on for 5-10 minutes and then go off. Sometimes it would be hours, sometimes it would do it several times in an hour. Call the AC/Heat Tech. He says "Thermostat", so $150 later (80 for t-stat, 70 for service call) we have a new thermostat. Next day, same problem. So I removed the new thermostat. The blower continued to cycle on and off (without a thermostat). Next day I replace the old thermostat (got money back for new one). Rewired control lines to exteriour compressor & found a leak in the vent pipe that had dripped on one of the roll over switches just above the burners. Unit seemed to be working fine. Until tonight. Turned t-stat on HEAT (AUTO FAN) in preparation for a cool over night temp and the blower immediately kicked on. I turned the thermostat off and the blower continued to run. I let it run for over 30 min then cut off AC power to the unit to stop the blower. When I reapplied power, the blower stayed off. I then reset the T-stat to a temperature that would allow the heat to kick on. When I selected heat again, the blower immediately came on along with the vent blower. The burners lit, the house warmed up and the burners kicked off. A few minutes later the vent blower went off, but the main blower continued to run until I again interupted AC power. I tried removing the T-stat, no change. The control board LED is steady on, not flashing, showing no faults. I ohm checked the roll over switch circuit, its good showing continuity thru-out. What Next? Maybe a sticking Blower Relay?
Unit is a Goodman GHP125-5 built in 1993.
 
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Old 02-10-13, 08:05 AM
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It very well may be a sticking relay. Is the relay part of the control board or separate?
 
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Old 02-10-13, 08:16 AM
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Now its...

Well, this morning I couldn't get the heat to come on even with the blower stuck on. Looked at the unit, now the LED on the Circuit board is flashing 5 times. According to the schematic on the inside of the door, this indicates "sticking gas valve, false flame detected". Now I don't know if this is directly related to the blower running, although it's supposed to run if it detects heat, or if its a new problem. Can this error be given if the gas valve is not sticking? i.e. a bad circuit board? BTW - circuit board contains all fan relays and connects directly to blower.
 
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Old 02-10-13, 09:06 AM
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That error code is most often a failed control board. To verify make sure there is no flame present at the burners. That error code will make the blower run.
 
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Old 02-10-13, 02:45 PM
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Unhappy Now its DeAd

Well, now its totally dead! The T-stat says its in heat mode but there is no reaction at the unit. No blowers, vents, flame, nothing! Verified power to the board. Just nothing coming off. With such a varied failure path, I betting something in the board has died. So, I'm off to find a new board. If that doesn't work, I'LL BE Back.....
Thanks
 
 

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