This is a York model G80C075120 Exterior forced air heater. The blower, igniter and fan work, the main burners ignite but then shut off 5 seconds later; cycle three times and then shut down. There is no error code. I?ve replaced the flame sensor Purged the gas valve, measured 9v from the control board on the two leads Re-inserted all the leads to the control board to insure good contact and bypassed the thermostat by leaving the ground attached and connecting the call for heat and blower wire twisted together with the same results. What am I missing ?
york furnace of woe
Nov 27, 2006
7 Replies
Reverse polarity will cause the problem you describe. Check and make sure you have 120 volts from black to ground, and 0 from white to ground. Larry
Hmmm, Ground is ground. 120V is between black(hot) and white(neutral). Trying 3 times and quitting is sure sign of error condition.
Hi, It's funny he is talking about ignitor and flame sensor and you are talking about pilot flame? Different subject.
If the polarity of the incoming power is reversed you will still have
120 volts between black and white and the furnace will do exactly as the OP described. I have seen it happen before-- more than once. Make sure the black is hot and the white is neutral. Around here, about 99+% of furnaces are connected with a pigtail and receptacle, so the polarity can be accidentally switched easily if anything is done anywhere in the circuit. Most furnaces will run ok during a/c use that way-- it will not show up until the heat is fired up. Larry
My furnace installation manual specifically warns about this possibility. Larry's suggestion and method of testing are both valid.
Don Young
thanks for the tips...flame sensor double checked, reading microamps under use...i'm afraid ground ( white ) is indeed ground
next step: a ball peen hammer
D>> If the polarity of the incoming power is reversed you will still have
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