bryant furnace fuse

hoops

have bryant furn model 986ta48080v17a....circuit board hk42fz064......with 100 percent of power off to unit it blows 3 amp fuse instant insertes....the fuse is correct amp...thxs

mattmia2

what thermostat is connected to it? is anything else connected to the thermostat? an external transformer or separate cooling?

hoops

digital thermostat....no batteries....guess direct wired......cooling/heating is zoned

JUGHNE

Zone motors.....where do they get their power?

If you remove that power supply does the fuse still blow?

hoops

don't know but with all power off and fuse still blowing wouldn't that have to be something that stores energy like a capacitor........very low tech here

ratio

It would have to be either power isn't completely off after all or a cross connect to something that isn't unpowered.

HomerJSmith

Is this something new or is it always happening from the installation?

hoops

"Just started not previous issue....main breaker off

Jamie Hall

I hate to say this, but fuses just don't blow all by themselves. Somewhere that fuse is getting power, and it would be well to find out where before you get powered yourself.

hoops

No worry as not poking around myself....has to be a bad capacitor  or diode maybe

mattmia2

You turned off the service disconnects for the house and it is still blowing? Is there a separate meter for an AC condenser?

If all of the power is off for the house it has to be a current through a water/cable tv/phone/gas service from a bad neutral from a neighbor or the utility finding its way back through your neutral.

Jamie Hall

A capacitor will not blow a fuse, unless it is a very large capacitor. A diode is not an energy source, and can't possibly blow a fuse by itself.

There must be an energy source somewhere still connected. If you've really turned off the service disconnect and it still blows, you have far more serious electrical problems than a blown fuse. You need a good electrician in there, yesterday morning, to find and fix the problem.

JUGHNE

You turned off the main breaker to the entire house or the "main" breaker for the furnace??

hoops

Turned off breaker that controls ac/heat.  Thermostat doesn't have batteries but I think direct wired.  Could that be a source or a bad circuit board

Jamie Hall

If you turned off only the breaker that serves the ac/heat, that should have killed ALL the power to the system -- and the fuse would have no reason to blow.

Therefore, you still have an electrical problem, and you still need an electrician, and the sooner the better.

You also may have a problem with the thermostat being mis-wired, although if you didn't change anything in the wiring that seems unlikely, You may also have a problem with the control board -- but that should be off with the breaker off.

Is there a separate transformer for the thermostat? If so, how is that powered? Besides the obvious -- it should be on the same breaker, and if it is the culprit it needs to be reconnected properly -- it could contribute, depending somewhat on exactly what the blown fuse protects.

hoops

Appreciate the input guys......going to get electrician to check things out as suggested.....will update later.....once again thxs

JUGHNE

Zone control power supply still on??

HVACNUT

Is there a humidifier with its own transformer that's not on the same circuit as the furnace?