rathrbefishn

Goodmand furnace not lighting

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if you have bad termo cuple it will not open gass valve,

if you hear buz coil and the gass will not open ,the gass valve is stuck,you have to tap on pipe and it will open up.

 

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I'm not a professional but I had a problem at friends house down the shore with a high efficiency gas furnace in early February.  Furnace stopped running first intermittently and then just wouldn't light yet the blower would run. Turned out that it had a blockage in a condensate trap something called a "p" trap which affected the pressure switch sensor and would not let the furnace light. I had to unhook some tubes, drain some water from them and get rid of some crap that had  accumulated in this plastic trap over the years.  After cleaning it started right up and has been running ever since.  Look on youtube and search for "gas furnace p trap" and you will find several short videos. Some are more informative than others but I found one that worked. It may look like the picture that I have attached. Good luck!

p trap.jpg

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Thanks for all the thoughts.  I had someone come by and take a peek.  Turns out my board is bad.  Ugh.  But he did look at all the easier stuff first and also "hotwired" to verify that the gas valve is good.  Hopefully new part will be in  a day or two.  The joys of home ownership.  FWIW, I had done some testing on my own yesterday and had come to the same conclusion, but wasn't confident enough to just spend $150+ just to swap out another part.  Thankfully I've got this guy that does this on the side so the hit wont' be too bad and I'll have him check my AC and heat pump for a spring checkup while he's here next.

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13 hours ago, Kml said:

What is that other electrical connection that gets completed after the blower runs to let the gas valve release the gas.

It is like a diaphragm or vaum actuated thing.

I had one like that go bad once.

 

That is called a pressure switch. Proves good draft after the inducer/force draft motor is on and working. The ignitor wouldn't glow if either control wasn't on or operating correctly.

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10 hours ago, rathrbefishn said:

Thanks for all the thoughts.  I had someone come by and take a peek.  Turns out my board is bad.  Ugh.  But he did look at all the easier stuff first and also "hotwired" to verify that the gas valve is good.  Hopefully new part will be in  a day or two.  The joys of home ownership.  FWIW, I had done some testing on my own yesterday and had come to the same conclusion, but wasn't confident enough to just spend $150+ just to swap out another part.  Thankfully I've got this guy that does this on the side so the hit wont' be too bad and I'll have him check my AC and heat pump for a spring checkup while he's here next.

How did you 'hot wire' the gas valve. Did you run 24 volts right to the gas valve. Like I said If you had a reading of 24v at gas valve with ignitor glowing and no gas. Valve is bad. No 24v at valve with ignitor glowing problem is else where.

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1 hour ago, rdbass said:

How did you 'hot wire' the gas valve. Did you run 24 volts right to the gas valve. Like I said If you had a reading of 24v at gas valve with ignitor glowing and no gas. Valve is bad. No 24v at valve with ignitor glowing problem is else where.

Actually it was the service guy that did that.  Pulled a hot off the board  and jumped it to the valve to verify it was working.  He had already come to conclusion board was bad (no 24v at valve, no connections loose,, etc).  He said he just wanted to double check and make sure valve was still good-  said that they don't fail very often in his experience but he wanted to be sure.   I had not detected 24V to the valve but wanted verification that there wasnt' something else that might be a simpler fix.

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Posted (edited) · Report post

Ok good. Let me know when you're back and running. Circuit Boards do have a lot of wires. Need to be able to read schematic. I'd suggest taking a before pic of board before removing wires. Also get the # of the board that needs to be replaced. Example Integrated circuit board B18099-13 replaced board FOR MODELS GMP 050-3, 075-3, 075-4....

Edited by rdbass

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