Coleman furnace flame rectification
#1
11-07-21, 03:27 PM
Coleman furnace flame rectification
Ok so I have a coleman TM9V060B12MP11A kicks on then off like its the flame sensor I'm getting ignition lock out due to retries code. Received new flame sensor and I'm still getting the same problem. So I pulled and cleaned the burners and still the same problem. Next I pulled the board and cleaned it up no obvious signs of bad/cracked solder joints, capacitors look good, and no corrosion in the terminals. Micro amps read all over at the flame sensor but I have a constant 104v going to the flame sensor and I'm getting .05 micro amps at the board (board calls for .1). I have checked that I'm getting a good ground from the breaker box and hot/ground is 120v common/ground is 0v polarity is correct hot/transformer is 96v. Any ideas before I breakdown and call Hvac repair
#2
11-07-21, 03:51 PM
Group Moderator
Welcome to the forums.
Not sure where you are getting 96v but that is low if it's supposed to be 120v.
You need to put a meter in series with the flame sensor rod. It needs to be a meter that can read ua (microamps). Once the flame is established you should be measuring a fairly stable current. It should not be all over the place. It should be somewhere between 2-5 ua.(DC) The higher the better.
The flame rod must be engulfed completely in the flame.
Not sure where you are getting 96v but that is low if it's supposed to be 120v.
You need to put a meter in series with the flame sensor rod. It needs to be a meter that can read ua (microamps). Once the flame is established you should be measuring a fairly stable current. It should not be all over the place. It should be somewhere between 2-5 ua.(DC) The higher the better.
The flame rod must be engulfed completely in the flame.
#3
11-07-21, 04:03 PM
96v is making sure 24v transformer is not wired in reverse but no matter what I do I can't get a stable reading from flame sensor I even bent the old sensor just to see if it made any improvements and still get drops into the negative. Makes me think I got a bad ground wire but it doesn't go back to the board it goes back to the vent pump so I'm not sure where the board gets its reading from ground side.
#4
11-07-21, 04:12 PM
Group Moderator
The flame sense system is from the control board..... thru the single wire.... thru the stainless steel rod.... thru the flame to the burner..... from the burner back to the control board via the metal chassis.
That means the fastening hardware.... and the burners themselves.... need to be clean and solid. The mounting screws for the burner frame and the control board need to be clean and tight. The ground to the house doesn't usually affect the flame sense measurement.
You can add an additional ground wire from the burner to the frame and then to the control board.
That means the fastening hardware.... and the burners themselves.... need to be clean and solid. The mounting screws for the burner frame and the control board need to be clean and tight. The ground to the house doesn't usually affect the flame sense measurement.
You can add an additional ground wire from the burner to the frame and then to the control board.
#5
11-07-21, 04:34 PM
Alright well I'm stumped I already cleaned the burner faces, where burners attach to housing, where housing attaches to the frame, ran a extra wire from where the board is grounded to frame to the burners and still no change. The flame sensor it's self can't be moved maybe 1/8 of inch side to side but trust me I've moved it every which way possible with the same outcome. There is a spot on my board to measure the micro amps and .5 is where it likes to sit every time at the flame sensor it is just chaos up to 4.7 down to -.8 and everywhere in-between. Just wierd this furnace has been running 10 plus years and never skipped a beat and now I can't get it to budge.
#6
11-07-21, 10:02 PM
If you don't already have it, the information contained in this manual might help. I would be interested in pages 36/37 as it might guide you into what could actually be causing your lock-out.
701379-UIM-C-0712.fm (pritchardmechanical.com)
Good Luck
701379-UIM-C-0712.fm (pritchardmechanical.com)
Good Luck
