Gas and Oil Home Heating Furnaces - coleman gas furnace unreliable
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WRENCHTURNER75
01-26-08, 03:04 PM
i have a coleman gas furnace that has a spark ignition, my problem is sometimes the furnace will run normally, and other times ill come home from work and all thats running is the little black motor off to the left of the furnace that has a air tube going down to it, so ill manually shut the furnace off then wait 30 seconds or so then turn it back on, the black motor starts up right away and sometimes after 30 seconds or so the gas will ignite and the furnace will run normall, other times the gas will not light up or even click for that matter, then thers times where the gas will click and light up but then go out after 5 or 6 seconds. the furnace is really unreliable as this happens alot at night, im constantly getting up and restarting this thing, sometimes ill have to shut it off and retsart it 4 or 5 times before it actually lights or stays lit! any help would be appreciated.:gmorning
ecman51`
01-26-08, 04:21 PM
You are talking to someone who is hot off the presses from working on Coleman's with spark ignition.
On one furnace it was the ignition controle module. But also on that furnace there were holes eating through the burner that had to get fixed.
On another identical Coleman it needed cleaning up at the electrodes.
It be very much worth your while to pull the burner [it only took me a few minutes - after shuting off the gas line petcock valve, then had to pipe wrench remove the gas line union next to the gas valve, then had to remove 4 screws that held on the gas valve, then had to remove 2 sets of wires from the gas valve. Then the gas valve came off. Then all I had to do is undo the other 4 screws that holds the burner in, then pull it out. Then remove the 2 wires from the electrode remembering which one goes on which one!] (you have that single tube type?) and inspect the burner for any developiong holes and to clean up all 3 (I presume) rods of the electrode assembly (this is direct spark ignition; no pilot. Left one is the spark power giver, the center one is the spark to ground reciever and the right one is the flame sensor). The left one with a big spark plug wire is the one that has the power in it (coming from the ignition module) for sparking. The center electrode recieves the spark and goes to ground, via the burner itself, so that means the bracket, how it is bolted, has to be making good ground (may be worth any disassembly at this time, to cut off rusty mount bolts for the electrodes, brighten up metal and replace the bolts with stainless steel ones. The grounding for the spark has to go through that joinery of how the electrode kit is clamped onto the burner, then since the burner is mounted to the furnace, there is a seperate green ground wire between one of the burner mount screw holes, and the ignition control module, to complete the grouding circuit for that center ground electrode.
Then while the burner is out and electrodes are exposed, brighten up all 3 rods with steel wool, fine emory cloth or scotchbrite pad. This is very important.
You can test to see if 24 volt A/C current is making it's way through the limit switch (located above the burner area,with 2 wires probably) into the pressure switch and then into the ignition control module. If it is not, then THAT is where your problem is - most likely between the incoming side of the limit control and the outgoing of the pressure switch. Easiest test is to work backwards by simply unplugging the one wire that goes between the pressure switch and the ignition control module, turn on the furnace and wait for the draft inducer motor to run, and then volt meter test between the pressure switch spade connector you took the wire off of, and put your other voltmeter lead on furnace metal anywhere.
If you have 24 volts on this test and no sound of spark - yes you should hear the sound but may not really see the spark well as it may be hidden from view - then that leaves the problem being a bad ignition control module, if you did the other stuff I spoke of. (With the likely presumption you have no gas delivery issue)
On one furnace it was the ignition controle module. But also on that furnace there were holes eating through the burner that had to get fixed.
On another identical Coleman it needed cleaning up at the electrodes.
It be very much worth your while to pull the burner [it only took me a few minutes - after shuting off the gas line petcock valve, then had to pipe wrench remove the gas line union next to the gas valve, then had to remove 4 screws that held on the gas valve, then had to remove 2 sets of wires from the gas valve. Then the gas valve came off. Then all I had to do is undo the other 4 screws that holds the burner in, then pull it out. Then remove the 2 wires from the electrode remembering which one goes on which one!] (you have that single tube type?) and inspect the burner for any developiong holes and to clean up all 3 (I presume) rods of the electrode assembly (this is direct spark ignition; no pilot. Left one is the spark power giver, the center one is the spark to ground reciever and the right one is the flame sensor). The left one with a big spark plug wire is the one that has the power in it (coming from the ignition module) for sparking. The center electrode recieves the spark and goes to ground, via the burner itself, so that means the bracket, how it is bolted, has to be making good ground (may be worth any disassembly at this time, to cut off rusty mount bolts for the electrodes, brighten up metal and replace the bolts with stainless steel ones. The grounding for the spark has to go through that joinery of how the electrode kit is clamped onto the burner, then since the burner is mounted to the furnace, there is a seperate green ground wire between one of the burner mount screw holes, and the ignition control module, to complete the grouding circuit for that center ground electrode.
Then while the burner is out and electrodes are exposed, brighten up all 3 rods with steel wool, fine emory cloth or scotchbrite pad. This is very important.
You can test to see if 24 volt A/C current is making it's way through the limit switch (located above the burner area,with 2 wires probably) into the pressure switch and then into the ignition control module. If it is not, then THAT is where your problem is - most likely between the incoming side of the limit control and the outgoing of the pressure switch. Easiest test is to work backwards by simply unplugging the one wire that goes between the pressure switch and the ignition control module, turn on the furnace and wait for the draft inducer motor to run, and then volt meter test between the pressure switch spade connector you took the wire off of, and put your other voltmeter lead on furnace metal anywhere.
If you have 24 volts on this test and no sound of spark - yes you should hear the sound but may not really see the spark well as it may be hidden from view - then that leaves the problem being a bad ignition control module, if you did the other stuff I spoke of. (With the likely presumption you have no gas delivery issue)
eslinger
03-01-09, 09:48 AM
Wrenchturner75,, i have the same problem with my colman presidentail evcon,,,not answer on what to do been told points in black motor stick, no one has a solution yet....
cyberdead
03-01-09, 10:08 AM
i have a coleman gas furnace that has a spark ignition, What is the model and Serial #'S my problem is sometimes the furnace will run normally, and other times ill come home from work and all thats running is the little black motor off to the left of the furnace that has a air tube going down to it,
does it have an LED on the board flashing a code?
so ill manually shut the furnace off then wait 30 seconds or so then turn it back on, the black motor starts up right away and sometimes after 30 seconds or so the gas will ignite and the furnace will run normall, other times the gas will not light up or even click for that matter,
Is the ignitor firing? Every time?
then thers times where the gas will click and light up but then go out after 5 or 6 seconds. the furnace is really unreliable as this happens alot at night, im constantly getting up and restarting this thing, sometimes ill have to shut it off and retsart it 4 or 5 times before it actually lights or stays lit! any help would be appreciated.:gmorning
Sounds as if it is having a hard time with the pressure switch...
Can be several things that would cause this.
When it does not fire check and see if the pressure switch is made..
If not then you need to check the flue for obstructions, Rusted blower wheel on the Inducer motor (small black motor.)
The tube and fitting on the pressure switch
Could also be another limit switch..
Get back to us after checking these things.
does it have an LED on the board flashing a code?
so ill manually shut the furnace off then wait 30 seconds or so then turn it back on, the black motor starts up right away and sometimes after 30 seconds or so the gas will ignite and the furnace will run normall, other times the gas will not light up or even click for that matter,
Is the ignitor firing? Every time?
then thers times where the gas will click and light up but then go out after 5 or 6 seconds. the furnace is really unreliable as this happens alot at night, im constantly getting up and restarting this thing, sometimes ill have to shut it off and retsart it 4 or 5 times before it actually lights or stays lit! any help would be appreciated.:gmorning
Sounds as if it is having a hard time with the pressure switch...
Can be several things that would cause this.
When it does not fire check and see if the pressure switch is made..
If not then you need to check the flue for obstructions, Rusted blower wheel on the Inducer motor (small black motor.)
The tube and fitting on the pressure switch
Could also be another limit switch..
Get back to us after checking these things.
ecman51`
03-01-09, 03:48 PM
Wrenchturner75,, i have the same problem with my colman presidentail evcon,,,not answer on what to do been told points in black motor stick, no one has a solution yet....
Points are usually not in motor. Usually in a switch device.
Think instead that someone told you the pressure switch may not be working? If so, there can be several causes besides it being the switch itself. The switch is designed to shut off when there is a problem. Post back to clear up this business about points in motor issue, and we can maybe help further.
Points are usually not in motor. Usually in a switch device.
Think instead that someone told you the pressure switch may not be working? If so, there can be several causes besides it being the switch itself. The switch is designed to shut off when there is a problem. Post back to clear up this business about points in motor issue, and we can maybe help further.