Gibson Electric furnace blower shuts off and on-short cycles

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Posts: 3
Joined: Thu Mar 10, 2011 3:47 pm

Fri Mar 11, 2011 12:23 pm

I have question need your expertise and advice.

Electric furnace is a Gibson(made by Nordyne in STL, MO).
Model number for air handler is GB3BM-042K-B
The heat element kit is model number H4HK020H-22
It is a 10 Seer condensing unit and R22.

Here is problem I am having. When I turn on the electric heat to the furnace and set to auto at thermostat, the heating elements come on like they are supposed to and then the fan blower comes on. Then within 30 seconds to several minutes or less the fan blower shuts off for 30 seconds or minute and then kicks back on and blows out heat with blower on for about 5-30 seconds or so. It is random on how long it kicks off and on, BUT it always blows out heat, so elements are working. And it is like someone is turning the thermostat or power to blower off and on like a light switch you would turn off and on at will or random.

I checked filter, it is clean, I then vacuumed out the cold air return duct and vent duct going to furnace, I then cleaned out and vacuumed out underneath the A coil and got everything inside the air handler and cleaned off everything stuck to underneath the A coil so to make sure air flow is pulling through A coil on up into the heating elements and blower, thus it is or should be getting plenty of return air. After I did all this and tried to run it again, for about 10-20 minutes the furnace blower run nonstop and cycled off and on with thermostat normally, then it suddenly started to do it again after this time, so thought maybe high limit switch, fan switch or heat sequencer is out or faulty maybe. Or may need to be taken out and cleaned, since it may have lot of dirt and build up on it possibly causing it to get hot and shut off and on the blower. I realize it is supposed to shut off and on for safety but something is not right.

I was not sure if it was the heat sequencer that would cause the blower to kick off an on, or fan switch, or the digital thermostat. Had worked for 4 years with the digital thermostat wired up like it is just fine until about 2 yrs ago then started doing this off and on stuff.

ONE Last thing, and you probably wondered how the heck has he been able to run that furnace now for 2 plus years with it shutting off and on. When it first happened 2 yrs ago I took the cover or panel off to the air handler when you face it where the power breaker is, and inside there is all the heating elements, limit switches, wires, harness and sequencers. Once I took off that metal cover plate to air handler on furnace the blower on furnace would run non-stop or well run and cycle off and on like normal after running and achieving desired or set temp on thermostat. Basically I have left the cover off for over 2 years and it has run blower and heating elements just like normal and no abnormal spike in electric bills.

Please offer what you can, I just found this website yesterday, after going over and cleaning out the electric furnace filter, A coil, and cold air return duct work. And there was really not a lot clogging it up or not much debris or dust or dirt there. So made me wonder if it is something other on furnace causing blower to kick off and on while heating elements come on.