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terreneuve · Feb 10, 2009, 01:48 PM

Hi

I have a 20KW Lincoln ( similar to Broan) Electric Hot Air furnace.

It is less than a year old and was working fine until today when the fan would not
Come on when the thermostat would request heat.

The furnace has a fan switch with gives the choice of fan on/off.

When the switch was "off" the fan would only come on when the thermostat requested heat. When the fan switch was turned "on" the fan stays on continuosly.

The problem now is the heating elements come on as required but the fan does not come on automatically. If I leave the fan "on" the I have heat and the elements cycle on or off as required but of course the fan stays on continuously.

Is this a relay problem?

Thanks for your help!

John

hvac1000 · Feb 10, 2009, 04:43 PM

Usually one of the sequencers controls the fan operation in the heat automatic mode.

terreneuve · Feb 10, 2009, 06:28 PM

There are 3 sequencers in the unit but it seems that one is wired to the fan - would I be correct to assume this would be the suspect sequencer?

Is it common for a sequencer to fail as the unit is only in service 4 months. Are these very expensive?

Also, there is what looks like a relay bolted to the fan shroud and wired to the fan motor- what is it?

Thanks again!

John

wmproop · Feb 10, 2009, 07:37 PM

(quote)Also, there is what looks like a relay bolted to the fan shroud and wired to the fan motor- what is it?

YOU ARE PROBABLY LOOKING AT A CAPICITER

wmproop · Feb 10, 2009, 07:41 PM

(QUOTE)Is it common for a sequencer to fail as the unit is only in service 4 months. Are these very expensive?

No not very common, if its only 4 months old the part should be under warranty, but maybe not the labor,, most companies will only replace the under warranty parts when replaced by a certified HVAC Tech,, decisions-decisions

hvac1000 · Feb 10, 2009, 09:23 PM

There are 3 sequencers in the unit but it seems that one is wired to the fan - would I be correct to assume this would be the suspect sequencer??

That should be the one that is causing the fan problem. The sequencers are in a cascade type hook up where the first in line operates the fan after a built in time delay in the sequencer itself kicks in when the thermostat calls for heat. The first sequencer also activates the first heat element. The rest of the sequencers are tied to the first and they all have a delay action to prevent a massive current draw on the house electric panel.

Sequencers are another cheap item with almost all of them being from china now days so they do not last near as long as the ones that were made here years ago.

They can be a pain to get wired correctly so I suggest you label the wires before removal.

terreneuve · Feb 11, 2009, 04:47 PM

Thanks for the help.

I'll replace the 1st sequencer and see if that solves the problem.

John

hvac1000 · Feb 11, 2009, 05:15 PM

Replace the one that controls the fan.

terreneuve · Feb 11, 2009, 05:41 PM

Thanks

That's what I meant:D

John