Residential HVAC Help?

kingmoochr

kingmoochr

WHARRGARBL
Our heater in on the fritz...It's a Coleman-labeled York TGLS060A12MP11B. It's been running hot then cool the last few months, and now it's randomly shutting down giving a code to "Check Pressure Sensor Wiring". I get 26v both sides of the pressure sensor when it does run...the real obvious problem is the relay on the board goes crazy, clicking on and off randomly. I'm going to solder on a new relay that is in the mail, but I was hoping someone here might have some experience w/ troubleshooting what sounds more like a board problem. The filter was cleaned (gold washable version) last summer. The installation is relatively new, with the furnace in the garage ducting basically straight up and out. The internet says maybe dirty flame sensor? backflow sensor? high limit being triggered? Anyone have tips on how to check these things for a garage mechanic w/ a voltmeter?
 
TerryM

TerryM

--/\~
Maybe the pressure sensor itself? If it's on the fritz, or the fan that makes combustion pressure is somehow not building enough, the sensor/switch may not be energizing the relay (or energizing it intermittently). I think that would keep (or turn) the gas valve off.
 
kingmoochr

kingmoochr

WHARRGARBL
Also had weird flashing from the board when the relay was going off. My futzing has it working more on than off now... relay and board (just in case) are in the mail. I'll put the voltmeter on it if it starts bugging out to check the voltage at the pressure switch.
 
HeatXfer

HeatXfer

Not Erudite, just er
Leave the board alone. To test, just jump out the pressure switch and see if the furnace runs regularly. If it's a blocked flue or a faulty switch the unit will start to run normally - BUT - check to see that the flue is clear and there's nothing blocking the vent. The pressure switch is there to prevent over heating and cracking the heat exchanger in the event the flue is blocked.

#8 on the PARTS LIST .pdf download
 
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kingmoochr

kingmoochr

WHARRGARBL
Is it possible a switch problem would cause the relay on the board to go crazy? video The furnace was receiving a heat demand from the thermostat, so it should have been blinking orange, not green at all. If the board was trying to say the switch was bad, it should have had 2 red blinks and not been trying to start up.
 
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kingmoochr

kingmoochr

WHARRGARBL
Update for posterity... put a replacement board in and it's working flawlessly so far. It was used from amazon, so I may still try and solder on the relay and give the old board another shot, but the used one only cost me 40 something bucks, we'll see how motivated I get.
 
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