Furnace Blower Fan Cycles On/Off During the off Cycle

[capwizard]

Goodman model NO. GMP075-4 Blower Fan Motor turn on and off irregularly while the thermostatic FAN switch is at off position, error code are one blink then 4 then 5 blinks, then red LED light on constantly and fan still running will stop and on randomly, drive me crazy!!

lastnight Id spend over three hours to troubleshooting, did everything this video said, its not thermostatics, its not the cables, its not sensors, I bypass fan limit switch, cleaned the air filter, same thing happened, so I order the PCB B1809913S, will update!..Any Helps ?........................

PS: Goodman B13709-08 limit switch tested on 0.4 Ohm should be ok, cleaned flame sensor still the same.

PS: the furnace gas fire up and work normally.

Blower Fan Motor Won't Shut off!- STEP by STEP Troubleshooting!
https://www.youtube.com/watch?v=fxRB4MVFOuo&t=451sodman

Troubleshooting the limit switch on the 80% AFUE gas furnace
https://www.youtube.com/watch?v=rBCW3qYjtr0


GMP075-4
https://cdn.badcaps-static.com/pdfs/...e2ee1acf8b.pdf

[stj]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

so what does the pcb look like?

in my experience, boiler control pcb's often suffer from cooked caps or cracked solder joints.
it's because or the enviroment they are in.

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

Three caps ESR tested good but I still changed one, the back has glue on it same as car's PCB, I hate that. no backside picture of PCB because I thought it's not gonna be the PCB.......

I ordered this PCB.......Circuit Board — B1809913S Goodman/Janitrol Furnace Control Board

This is a guaranteed genuine Goodman OEM replacement circuit control board for several Goodman, Amana, and Janitrol units. All of our parts are shipped factory direct, giving you the assurance you need for a quality replacement on your furnace, air conditioning condensing unit, or other Goodman product. The B1809913S replaces outdated part numbers B1809908, B1809906S, B1809908S, B1809910, B1809913, DB1809906S, DB1809907, DB1809908S, DB18099013, and 1809913S.

[stj]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

well the soldering on the relays & spade connector tabs is all under stress.

[sam_sam_sam]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

Three caps ESR tested good but I still changed one, the back has glue on it same as car's PCB, I hate that. no backside picture of PCB because I thought it's not gonna be the PCB.......

I ordered this PCB.......Circuit Board — B1809913S Goodman/Janitrol Furnace Control Board

This is a guaranteed genuine Goodman OEM replacement circuit control board for several Goodman, Amana, and Janitrol units. All of our parts are shipped factory direct, giving you the assurance you need for a quality replacement on your furnace, air conditioning condensing unit, or other Goodman product. The B1809913S replaces outdated part numbers B1809908, B1809906S, B1809908S, B1809910, B1809913, DB1809906S, DB1809907, DB1809908S, DB18099013, and 1809913S.

Most of the time these board are repairable most of the time it is bad soldiering joint that are bad or bad relays I would also replace the caps as well

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

Thank you will go back and check the soldering. How can I get rid of that semi-transparent glues?

[stj]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

try white spirit first, that melts the wax-polymer type.

if that wont work, see if the soldering iron will break it up.
DONT try this first, if it is wax-polymer then it will mess up the iron like hotglue!

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

Thank you, will try it tonight, will update.

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

After did bad connectors correction, till has the same situation.

What happen change NEW PCB still the same, this unit is A cool and Hot central unit, Is that possible, the signal from cooler keep give dirty filters or high humidity error signals to confused the PCB to blow the fan???................

Pic 11 : is that normal cheeses ground to AC hot shows AC 27 V ?

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

There has A blue and yellow wire, what is that? Maybe the one gave fault signal?

[petehall347]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

After did bad connectors correction, till has the same situation.

What happen change NEW PCB still the same, this unit is A cool and Hot central unit, Is that possible, the signal from cooler keep give dirty filters or high humidity error signals to confused the PCB to blow the fan???................

Pic 11 : is that normal cheeses ground to AC hot shows AC 27 V ?

hot and neutral are maybe swapped at some point or simple bad connection . is that line voltage you are measuring ?
27v on neutral is pretty high if that is so .
check supply is good order .

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

It is the thermostat red wire AC 27v to chassis ground. Sorry Im must be hungry #9 type to cheese ground.

[petehall347]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

i do not have the schematic so cant comment further without it ..
what is the order of normal operation ?

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

Thank you, Here is furnace model NO.....GMP075-4

https://cdn.badcaps-static.com/pdfs/...e2ee1acf8b.pdf

[petehall347]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

have you checked this ....page 38 ..
The auxiliary limit switch (B13701-55) is a safety control
that senses high temperature within the furnace or duct work.
This control is preset to open at 120°F and close at 90°F. It
is not adjustable and automatically resets. The control is
located in the blower compartment of the furnace on the
blower housing. Auxiliary limits may be on the side or front
of the blower housing.

[petehall347]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

sorry think that was wrong model ...

[petehall347]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

when the motor runs erratically does it try and light the burner ?

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

"the motor runs erratically does it try and light the burner"
No , when I set up thermostat to heat, the burner works flawless.

[petehall347]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

did you try disconnecting the wall thermostat to rule it out as a problem ?
i do suspect this is a fault with a heat sensor in the unit . or simply a poor connection in the wiring .

[capwizard]

Re: Furnace Blower Fan Cycles On/Off During the off Cycle

Thank you, I did exactly the same test as this guy doing.

Blower Fan Motor Won't Shut off!- STEP by STEP Troubleshooting!
https://www.youtube.com/watch?v=fxRB4MVFOuo&t=451sodman

in the picture I clean the ground point of Flame Roll Out Switches.