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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22107
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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My air handler fan is not working. I can home and the trip

Customer Question

My air handler fan is not working. I can home and the trip was out, i put it back in and the compressor started up but the air handler fan did not switch on. I crossed the wires on the fan relay to bypass it and still no joy. The capacitor looks good and has no bulging and the fan moves freely when pushed. I am thinking it may be the thermostat at fault suggestions please
JA: Did you double-check the thermostat's settings? And what about the filters?
Customer: I already change the filter recently and the coil is not iced up. I also lowered the temp on the thermostat.
JA: Do you plan on doing the work yourself?
Customer: Possibly depending how how complicated it gets
JA: Anything else we should know to help you best?
Customer: The compressor will run without the fan so I am thinking the unit believes the fan is rotating!
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and then connect you two.
Submitted: 5 months ago.
Category: HVAC
Expert:  BillyHvac replied 5 months ago.

Hello,

My name is Billy. Do you mind a test at the thermostat first? We would need to remove the top section where we can see the thermostat wires

Customer: replied 5 months ago.
ok done
Expert:  BillyHvac replied 5 months ago.

locate R wire and G wire..this is the bypass for blower that takes thermostat out of the equation....short r to g with a U shaped wire....or remove and twist together...tell me if blower starts

Customer: replied 5 months ago.
No response when the wires are crossed
Expert:  BillyHvac replied 5 months ago.

thank you.

Now short R to Y and tell me if outdoor unit kicks on

Customer: replied 5 months ago.
that works
Expert:  BillyHvac replied 5 months ago.

do you mind some test in the air handler?

Expert:  BillyHvac replied 5 months ago.

and what is make/model

Customer: replied 5 months ago.
it is a carrier 5 ton unit not sure of the model. I dont mind testing the air handler I already have the front panel off
Expert:  BillyHvac replied 5 months ago.

can you post a pic of the circuit board and close prox around it?

Customer: replied 5 months ago.
picture attached
Expert:  BillyHvac replied 5 months ago.

how many wires go to the motor?

Do you know if you have the ecm motor with lots of wires or a standard motor with 4-5?

Customer: replied 5 months ago.
model no is fa4bnf060
Customer: replied 5 months ago.
it is standard 5 wires with additional 2 brown returning to the capacitor
Expert:  BillyHvac replied 5 months ago.

thank you just pulling up schematic....with power on...thermostat set for fan on...any door safety switch taped down...if you hand spin the blower wheel does it try to run...spins and stops or is stiff?

Customer: replied 5 months ago.
The black and red are terminated and the blue goes to the relay the yellow to another switch (common) and the yellow/green is grounded to the motor fan housing
Customer: replied 5 months ago.
no motor spins freely but does not run under its own power
Expert:  BillyHvac replied 5 months ago.

do the spin test on wheel...and also if you have a meter put one lead on blue and other lead on yellow...240v present = bad motor

NO 240v present = bad board

We already know we have unit power and transformer as the outdoor unit runs...so it is down to board or motor

Customer: replied 5 months ago.
red end of meter on yellow and black on blue no voltage detected
Customer: replied 5 months ago.
blue to unit getting 25v
Expert:  BillyHvac replied 5 months ago.

you have 2 main power wires coming into the air handler..what do they read?

Customer: replied 5 months ago.
red wire 115v black wire also 115v
Expert:  BillyHvac replied 5 months ago.

what is black to red and not to ground...hot to hot

Customer: replied 5 months ago.
when i go black to red not getting a reading
Customer: replied 5 months ago.
apologizes had meter wrong voltage setting now getting 232v
Expert:  BillyHvac replied 5 months ago.

thank you..

now getting toward the end.....there is a terminal strip r,g,t,ccc

Short r to g and tell me if any click on board.

Customer: replied 5 months ago.
crossed r and g wires on board no click
Expert:  BillyHvac replied 5 months ago.

ok you have a bad board.

R to y activates cool solenoid but r to g does not active fan relay.

You have correct voltage to unit.....it is just the relay is not closing to start motor.

You need to replace the fan board.

Billy

Customer: replied 5 months ago.
ok thanks will do first thing tomorrow
Expert:  BillyHvac replied 5 months ago.

just rate service to remove from active list. I am avail for 30 days of followup after rating.

Billy