Blower not coming on (Lennox)
#1
03-26-14, 05:01 PM
Blower not coming on (Lennox)
Hi guys!
I woke up yesterday to my furnace not blowing heat through the registers.
My furnace is a Lennox elite series, model G24M3, downdraft. I have searched the forum and seen similar problems but, am still not able to diagnose. (I'm not that good with electical)
The unit comes on, ignites, runs for 30-40 seconds, trips something????
and flames go out. The diagnostic board shows 4 flashes, which says: primary/secondary limit switch is open or flame rollout switch is open(2)
Any help would be appreciated......
I woke up yesterday to my furnace not blowing heat through the registers.
My furnace is a Lennox elite series, model G24M3, downdraft. I have searched the forum and seen similar problems but, am still not able to diagnose. (I'm not that good with electical) The unit comes on, ignites, runs for 30-40 seconds, trips something????
and flames go out. The diagnostic board shows 4 flashes, which says: primary/secondary limit switch is open or flame rollout switch is open(2) Any help would be appreciated......
#2
03-27-14, 05:01 AM
If it runs for that long the blower should come on with the board, if it doesn't it will trip the high limit. I didn't look at the model number, does that have an ECM motor?
#4
03-27-14, 10:17 AM
Group Moderator
Welcome to the forums.
Your furnace uses a standard multitap motor.
Have you tried putting your thermostat in FAN ON mode to see if the blower works then ?
If that doesn't work try opening the blower access cover to see if you can turn the blower by hand. Turn power off before removing door.
Your furnace uses a standard multitap motor.
Have you tried putting your thermostat in FAN ON mode to see if the blower works then ?
If that doesn't work try opening the blower access cover to see if you can turn the blower by hand. Turn power off before removing door.
#5
03-27-14, 03:04 PM
PJ, thanks for your response. I just turned the thermostat to FAN ON. The unit cycled, flame ignition occurred, ran exactly 60 sec. and I'm guessing here, trips something and flames out. At no part of the process did the blower come on. I'll try turning by hand, next.....
OK. The blower turns freely.
OK. The blower turns freely.
Last edited by cutback; 03-27-14 at 05:12 PM.
#7
03-30-14, 12:12 PM
Group Moderator
The blower turns freely. Was the motor warm or hot ?
You could possibly have a defective start capacitor or a defective fan relay.
Do you have access to a VOM (volt ohmmeter) ?
You could possibly have a defective start capacitor or a defective fan relay.
Do you have access to a VOM (volt ohmmeter) ?
#9
03-30-14, 01:13 PM
Group Moderator
You will need to put the thermostat in FAN ON mode. You'll have to open the blower door and hold the safety switch in. You need to check for voltage to the blower motor on the control board. It should be labeled. You'll have five wires connected inside the red box....the ACB low is the FAN ON output. Check from there to neutral.
Your furnace manual........ Lennox manual_PDF
Your furnace manual........ Lennox manual_PDF
#10
03-30-14, 02:29 PM
PJ, I have the early model control board (A3) I also do not have an access panel door switch. When I put my leads on my meter to the ACB low that you high lighted and a white wire, which I presume is a neutral, I'm not showing any voltage. Hopefully, I'm understanding correctly. I did check my meter first, in a recepticle, to make sure it was functioning correctly and all was good.
#11
04-01-14, 05:03 PM
Well, as the fix-it knowledge came to a standstill, I had a tech out.....
I'm just posting so others with similar problems may benefit.... The cause of my problem was a circuit board failure. Shorted and fried on the backside of the board @ the Fan relay. That is why I had no voltage on my meter. Best of luck to the rest of you with your diagnosing problems.
I'm just posting so others with similar problems may benefit.... The cause of my problem was a circuit board failure. Shorted and fried on the backside of the board @ the Fan relay. That is why I had no voltage on my meter. Best of luck to the rest of you with your diagnosing problems.
#12
04-01-14, 06:01 PM
Group Moderator
Unfortunately the solder quality leaves much to be desired.
Thanks for stopping by and filling us in.
Thanks for stopping by and filling us in.
