furnace short cycling
#1
12-01-21, 10:11 AM
furnace short cycling
I'm experiencing this like others. I cleaned the flame sensor, changed the filter, cleaned the evaporator coil, it was dirty, and still no change. Fires up, runs a few minutes, burners shut off, on the third try, it will relight, and it will do this for three cycles until it locks out. It's a Goodman GPG 10 single package gas-electric h & c unit, vintage 2005, the whole shebangs sits outside in the weather. Any chance it's my thermostat? I know it's a precision control, and last year I dropped it from about shoulder height, but it ran the AC all summer........thanks for your advice.
#2
12-01-21, 10:33 AM
Group Moderator
That unit shows a control board with diagnostic LED. Have you checked that for a fault code ?
The board is usually located near where the power wiring enters.
There may be a sight glass in the door to look thru.
The board is usually located near where the power wiring enters.
There may be a sight glass in the door to look thru.
#3
12-01-21, 10:38 AM
yes, it blinks once, and the owners manual says lockout due to failed ignition of flame dropout. The burners light for various amounts of minutes but never more than ten, and then the flame disappears.
#5
12-01-21, 10:43 AM
Group Moderator
You need to watch it when it first happens. After several attempts the code changes to lockout.
#6
12-01-21, 11:00 AM
ok, I can do that. Are you saying watch the LED board when the flame disappears from the burners? I think I did that and it stayed steady red on, which is control ok is standby, call for heat, cool or fan modes in the owners manual. But I can watch it when it does its thing.
#7
12-01-21, 11:27 AM
ok, when the flame disappeared from the burner, the red light was just steady on; when it failed to light on the third try, it started to flash, but it was just one flash. the owners manual says there's .25 second flash on, then .25 second off, and a full 2 seconds in between, and I'm reading just one flash
the owners manual:
a red led light is provided to indicate system fault as follows
Steady On control ok
Stead Off no power
1 flash lockout due to failed ignition or flame dropouts
2 flashes open end switch
3 flashes end switch closed without induced fan motor on
4 flashes limit switch is open
5 flashes flame detected with gas valve closed
6 flashes compressor output delayed from short cycle/staging timer
I'm pretty sure I'm reading it correctly, .25 seconds is a short flash, and then 2 full seconds in between...
the owners manual:
a red led light is provided to indicate system fault as follows
Steady On control ok
Stead Off no power
1 flash lockout due to failed ignition or flame dropouts
2 flashes open end switch
3 flashes end switch closed without induced fan motor on
4 flashes limit switch is open
5 flashes flame detected with gas valve closed
6 flashes compressor output delayed from short cycle/staging timer
I'm pretty sure I'm reading it correctly, .25 seconds is a short flash, and then 2 full seconds in between...
#8
12-01-21, 11:34 AM
Group Moderator
Page 14 starts discussion on troubleshooting. A fairly common problem is burner rust inside the burner especially with a packaged unit that is outside in the weather. The burners would be taken out and at least blown out.
If you observe the flames they need to hit and engulf the flame sensor rid fairly quickly.
You may need to monitor the flame rod current for an issue.
Goodman GPG 10 downloadable manual
If you observe the flames they need to hit and engulf the flame sensor rid fairly quickly.
You may need to monitor the flame rod current for an issue.
Goodman GPG 10 downloadable manual
#9
12-01-21, 11:50 AM
thanks, Pete. I guess I'm seeing some flame "rollout" but I wouldn't say it was a whole lot. It's intermittent. Inside the exchanger, it looks like there's some type of screen, and that's all orange when the burners are lit. With that description, would you think taking the burners out and hitting them with a wire brush and blowing them out would be the fix? In your opinion. Thanks again.
#10
12-01-21, 11:58 AM
Group Moderator
Based on servicing packaged units.... yes... clean the burners.
Clean the burner orifices too.
Clean the burner orifices too.
#11
12-02-21, 06:49 AM
Hello, good morning
I cleaned the burners and orifices, they really weren't dirty, actually, but I put a wire brush on them. I used to line cook in a restaurant, cooked on gas, feel qualified to offer my opinion on whats a dirty burner. Man, those were the days!
Cleaned the orifices too. No change. This unit has a 20 year Heat X warranty, I suppose the issue there would be is there a part available these days.
Next step call in a contractor?? Thx
I cleaned the burners and orifices, they really weren't dirty, actually, but I put a wire brush on them. I used to line cook in a restaurant, cooked on gas, feel qualified to offer my opinion on whats a dirty burner. Man, those were the days!
Cleaned the orifices too. No change. This unit has a 20 year Heat X warranty, I suppose the issue there would be is there a part available these days.
Next step call in a contractor?? Thx
#12
12-12-21, 04:50 PM
Gee.. i have exact same issue. the difference is that i have no error code coming out. the light on the board is solid and it does not locked out. Mine runs about 3 mins and stops before it reaches the temp. I am not sure what to look for.
