Inducer Fan

(Tim J. Hejnicki) #1

Correct me if Im wrong… a Natural Gas, Central Air system, should the inducer motor fan spin while the AC is running?

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(David A. Andersen, TN HI# 40) #2

Is it running or spinning?

(Tim J. Hejnicki) #3

Spinning., Seriously i have only seen them spin during the heating cycle, not during the Ac cycle..

(Gary Reecher) #4

If the inducer fan is spinning during a/c mode without power being applied to the inducer motor there is a serious breach in the heat exchanger allowing circulation air to blow through the heat exchanger wall and spin the inducer. If you get air blowing out the inducer outlet without the inducer spinning you have the same problem. Recommend an HVAC inspection ASAP.

(Raymond E. Wand) #5

It could also be improperly wired. No the Power Vent should not be running while A/C is operating.

(David A. Andersen, TN HI# 40) #6

Thank you Gary, I got side tracked.
I concur.

If the fan is powered, it does not mean it was wired wrong. The inducer often comes on in the event of a "fault" detected by the controller or a bad controller. In any event, it requires evaluation by a licenced professional.

Would there happen to be another induced draft blower elsewhere in the flue system or on another appliance attached to that flue system? I have seen h2o htrs with induced draft blowers installed because the furnace was induced and sharing the same flue.

(Tim J. Hejnicki) #7

Thanks to all, you guys have shed some light on the subject for me..

No there was not another vent tied into this one, the system was basic.
Furnace in the attic water heater in the garage.

(Bruce M. Graham, III, CMI) #8

If the home is overly pressurized, positive or negitive, it can cause the fan to free spin, air flow from the stack.

(David A. Andersen, TN HI# 40) #9

You have another big problem there also.

(Gary Reecher) #10

Many 80 percent furnaces were originally ok'd that they could be side wall vented with high temperature plastic vent: Plex Vent etc. that has since been recalled. B vent with a barometric damper and a side wall venter were installed in place of the high temperature plastic vent.

(Raymond E. Wand) #11

If the home is overly pressurized, positive or negitive, it can cause the fan to free spin, air flow from the stack.

I don't see how that could happen if this is a high eff. with its own outside air make up?

(Don Ellis) #12

I also have this issue. Inducer fan is running during A/C cycle under power and blower motor isn’t shutting off even when A/C compressor shuts off when temp is reached.

New fan motor, new high limit switch.

(Rolland H. Summers) #13

Ive seen this happen when a main control board fails had one in a package unit that got moisture on it blower fan on all the time inducer motor was running heating and air both still functional. No keep in mind there are many boards out there that would not work if draft motor was stuck on as pressure switch would be closed before the call for heat. That would cause a fault as pressure needs to be open when the call for heat is applied inducer motor then closes switch proving to control that draft motor is working.