My furnace is short-cycling. I've tried the following:
- replaced the flame sensor
- Shorted the thermostat heat demand signal
- Checked the blower capacitor
- Checked the air intake filter
- Checked the exaust vent
It seems to only works after I cut the power to it for 8+ hours
When it starts working it will work for about 48 hours and then return short cycling.
It has only begun short cycling at night (maybe temperature related).
What else should I trouble shoot.
Best Answer
I would start by trying to find a service manual for your furnace, and see if it has a troubleshooting flow chart.
I am thinking either:
If the control board is detecting something wrong, it might throw an error code. Previous systems I've used had an LED on the board that would blink out the error code.
You might be able to check the output of the various sensors by back probing the connectors. You can do your 8 hour reset to determine the 'good' values, then test it when it is short cycling to see if these are different enough to cause the control board to think something is wrong.
Look over the control board for signs of damage - blown capacitors, burn marks.