Heil 5000 Blower Motor Runs Continuously Blowing Cold Air

boisechick3770

My Heil has had this problem 3 times before in the last eight yrs...the first time a tech came out and reset a switch he said most people didn't know about and it ran fine for another yr or so....he said because of the high wind storm that we had it had tripped something....

The second time it happened....the other tech that was called form a different place said my heat exchanger was bad and needed replaced...which i found out wasn't the case because someone else was called...and they came out and fixed it....and it worked fine...this was two yrs ago....now...again...same time of yr... it's doing the same thing again...
IT blows out cold air and you cannot shut off the blower motor from the thermostat ...it just blows cold air...

Note: my daughter has been turning the switch on the thermostat fan setting to "ON" lately thinking she's turning on the heat ...instead of leaving it in "auto" mode....could this be why it is doing this? I've come home from work several times to find it's been running all day long.....

Doc Holliday

Your unit is tripping the high temperature limit switch. Both the draft inducer motor (gas furnace, right?) and the blower will come on no matter what as the furnace is trying to remove any excess heat. No heating will work until the switch is rest.

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Thanks.

Doc Holliday

Those switches trip due to excessive heat in the furnace, usually due to an air flow restriction. Do you have a/c as well? I'd check your evaporator coil and have it cleaned as needed and make sure the filter is clean.

When an evaporator coil is dirty it restricts the air flow causing the heater to become much hotter than it should, tripping the high temperature limit switch(es).

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Thanks.