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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Furnace is not able to keep power to it.keeps blowing the circuit

Customer Question

furnace is not able to keep power to it.keeps blowing the circuit breaker
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.
Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.What have you checked so far? Have you inspected the wiring? The blower motor?
Customer: replied 1 year ago.
blower motor spins freely
wiring looks all plugged in
Customer: replied 1 year ago.
I replaced the circuit breaker in the fuse box
Expert:  Tim H. replied 1 year ago.
OK, well the most likely causes for a tripped breaker are a bad blower motor or some wiring that is bad, burned, etc.
Customer: replied 1 year ago.
where is the capacitor for the blower motor?
Expert:  Tim H. replied 1 year ago.
It would be down in the lower compartment in the vicinity of the blower motor itself.
Customer: replied 1 year ago.
is it separated from the motor itself or attached?
Expert:  Tim H. replied 1 year ago.
Usually separate from the motor, not attached.
Customer: replied 1 year ago.
this is an air conditioner as well
Expert:  Tim H. replied 1 year ago.
I would inspect the capacitor, as well to make sure it hasn't "blown"
Customer: replied 1 year ago.
been looking for it
Customer: replied 1 year ago.
can you tell me or show me a picture of what it looks like?
Customer: replied 1 year ago.
doesent seem to be in the schematic
Expert:  Tim H. replied 1 year ago.
That model you gave me, G2D95 is actually a cased coil, not your furnace
Customer: replied 1 year ago.
where is the model # *****?
Expert:  Tim H. replied 1 year ago.
see here
Expert:  Tim H. replied 1 year ago.
Inside the top door of the furnace
Customer: replied 1 year ago.
that's where I got it from
Expert:  Tim H. replied 1 year ago.
The capacitor would look similar to this
Customer: replied 1 year ago.
near the blower motor
Expert:  Tim H. replied 1 year ago.
It should be. Follow the blower leads. Some go to the furnace board. There may be a couple of brown leads that go to the capacitor.
Expert:  Tim H. replied 1 year ago.
If this unit has a variable speed blower (ECM) it will not have a capacitor
Customer: replied 1 year ago.
no capacitor then
Customer: replied 1 year ago.
got a circuit board looking thing I can get a model #
Expert:  Tim H. replied 1 year ago.
But remember, the blower motor is not the only reason for a unit tripping the circuit breaker. I would start by inspecting all high voltage (120 V) wiring. Check the power switch on the side of the unit. Make sure that there are no loose wire nuts, etc.
Expert:  Tim H. replied 1 year ago.
This may take some time, so if you want to go ahead and do this and come back to it later, that's fine. You have about 5 minutes of chat time left, then it goes to Q and A mode.
Customer: replied 1 year ago.
check this
white Rodgers model#50a51-210-05
Expert:  Tim H. replied 1 year ago.
It's OK, I found the armstrong model number and we're good.
Customer: replied 1 year ago.
integrated?
capacitor?
Expert:  Tim H. replied 1 year ago.
On an ECM motor, there is a module attached to the back of the motor. This sometimes acts up.
Customer: replied 1 year ago.
under a cover?
Expert:  Tim H. replied 1 year ago.
Again, you need to go over everything, not just the motor. Let's not assume it is the motor.
Customer: replied 1 year ago.
ecm?
Customer: replied 1 year ago.
no acronyms
Expert:  Tim H. replied 1 year ago.
That's what variable speed motors are called.
Expert:  Tim H. replied 1 year ago.
Electrically commutated motor
Expert:  Tim H. replied 1 year ago.
ECM
Customer: replied 1 year ago.
thank you
Customer: replied 1 year ago.
so this model doesn't have a capacitor
Expert:  Tim H. replied 1 year ago.
We're down to 3 minutes on the chat. I would start inspecting the board, the high voltage wiring, the switch on the side, etc. Something is shorting to ground and causing breaker to trip
Customer: replied 1 year ago.
gimmi a list of what it could be
Expert:  Tim H. replied 1 year ago.
The board (tip it over, inspect the back), the power switch (looks like a light switch), the high voltage wiring inside the furnace (any 120 volt wiring), even the blower door safety switch
Expert:  Tim H. replied 1 year ago.
The blower motor could be bad, but it is difficult to see anything on the outside of ECM (variable speed) blower motors. If everything else checks out, you could remove the blower motor and inspect it. Take the module off the back of the motor and look inside at the electronics.
Customer: replied 1 year ago.
I been running bak and forth. the second I hit that blower safety switch is when it loses power
Expert:  Tim H. replied 1 year ago.
Have you tried taking the leads off the blower door safety switch (with breaker off) and just connecting these together and bypass the actual switch?
Customer: replied 1 year ago.
no
Customer: replied 1 year ago.
hard to test anything w/o power
Expert:  Tim H. replied 1 year ago.
I would try that. These switches are cheap and sometimes go bad. We have to do this by process of elimination.
Expert:  Tim H. replied 1 year ago.
Also, turn power off and tip the boards to inspect the backs of the circuit boards to make sure we don't have a burned spot on the board
Expert:  Tim H. replied 1 year ago.
The other thing I'd do is check and see if this unit has what looks like a light switch on the side or near the unit that is basically a power switch. Take the cover off, inspect this and see if this might be bad.
Expert:  Tim H. replied 1 year ago.
We are basically checking anything that is 120 volts on the unit which includes the circuit board, the blower door safety switch, the light switch (power switch), the wiring, and finally the blower motor.