Furnace problem in package unit
#1
11-26-20, 07:22 AM
Furnace problem in package unit
I have a 15+YO Lennox AC/gas furnace package unit.
AC acted up 2 summers ago and the unexpected fix was thermostat - I bought a same model - a Honeywell AA battery operated one, and AC has been working fine.
Furnace acted up same winter, wouldn't start, my DIY fix was sticking an object under all those tied-up spaghetti wires in the control box, jack them up, and that did the trick and the furnace worked all winter.
Furnace acts up again this winter. The same trick works but now I have to jack those wires up at certain spot every time to make the furnace go through the full sequence of <blower motor running--ignition makes fast 20 some clicks--flame comes on>.
The problem then is when the room reaches set temperature the furnace goes off of course, then to maintain that temperature it comes back on every 10-15 minutes or so but it permanently shuts off after coming back on once or twice, won't react to the thermostat, until I go over and play with the spaghetti wires and jack it up again at the sweet spot.
If it's not jacked up at a sweet spot these symptoms can present:
Blower motor will run and shuts off after a short period
Blower motor will continuous run (fan is set to Auto on the thermostat) but no ignition to start the flame
Blower motor runs, ignition clicks but not long enough to start the flame
It was suggested by a friend that it could be a low voltage wire. If I pluck some random wires in the spaghetti, some of the above mentioned symptoms may show.
Picture attached,
Your ideas/suggestions?
AC acted up 2 summers ago and the unexpected fix was thermostat - I bought a same model - a Honeywell AA battery operated one, and AC has been working fine.
Furnace acted up same winter, wouldn't start, my DIY fix was sticking an object under all those tied-up spaghetti wires in the control box, jack them up, and that did the trick and the furnace worked all winter.
Furnace acts up again this winter. The same trick works but now I have to jack those wires up at certain spot every time to make the furnace go through the full sequence of <blower motor running--ignition makes fast 20 some clicks--flame comes on>.
The problem then is when the room reaches set temperature the furnace goes off of course, then to maintain that temperature it comes back on every 10-15 minutes or so but it permanently shuts off after coming back on once or twice, won't react to the thermostat, until I go over and play with the spaghetti wires and jack it up again at the sweet spot.
If it's not jacked up at a sweet spot these symptoms can present:
Blower motor will run and shuts off after a short period
Blower motor will continuous run (fan is set to Auto on the thermostat) but no ignition to start the flame
Blower motor runs, ignition clicks but not long enough to start the flame
It was suggested by a friend that it could be a low voltage wire. If I pluck some random wires in the spaghetti, some of the above mentioned symptoms may show.
Picture attached,
Your ideas/suggestions?
#2
11-26-20, 08:46 AM
Member
Not that it’s directly related to your issue, but has the heat exchanger been checked in that unit recently? A 15 year old gas pack probably has a cracked or rotted heat exchanger that has to be addressed.
For the wiring, you’ll have to pick through it and find the loose connection. Does the unit get a call to run without moving the wires? Can you read a call with your meter?
For the wiring, you’ll have to pick through it and find the loose connection. Does the unit get a call to run without moving the wires? Can you read a call with your meter?
#3
11-26-20, 09:05 AM
Group Moderator
At one time I advocated DIY control board repair but it was received negatively by the other pros here and visitors. Since that time I only recommend board replacement. It was pointed out that an inadvertent solder bridge could render the safeties inoperative.
With the age of that unit.... the board should be replace anyway.
With the age of that unit.... the board should be replace anyway.
#4
11-26-20, 04:35 PM
Back to roughneck77, the heat exchanger hasn't been checked since I bought the house (first house) over 2 years ago, worked through first winter no problem... The furnace won't get a call without moving the wires. It is essential that a piece of something, in this case a piece of PVC T-socket is jacked underneath the wires for the furnace to come on.
Meanwhile I may have found a permanent sweet spot for now. It's been running all day.
Back to all, I feel the same about the control board, too. Will go ahead and order one. I am up for a $150 board than a $2500 new unit at this moment.
Meanwhile I may have found a permanent sweet spot for now. It's been running all day.
Back to all, I feel the same about the control board, too. Will go ahead and order one. I am up for a $150 board than a $2500 new unit at this moment.
#5
11-26-20, 05:12 PM
Member
Check the heat exchanger. The unit is 15 years old.
I’m not trying to sell you a new unit, in fact I hope your unit is structurally sound. But a 15 year old packaged unit needs checked. Its a major safety issue.
I’m not trying to sell you a new unit, in fact I hope your unit is structurally sound. But a 15 year old packaged unit needs checked. Its a major safety issue.
#8
02-15-21, 09:58 AM
Update on the original post:
Ordered a replacement control board in early December 2020, postal service was a train wreck during end of year holiday season due to staff shortage from COVID - took 4 weeks for the board to arrive. During all that time the quick and dirty trick of jacking the cables up kept the furnace working, I was planning on waiting til spring to change out the board if it continues to hold up.
...Until last night when temperature dropped to -20. Furnace finally gave out, wouldn't ignite and falls into constant loop of fail to ignite and reattempt. it would rapidly click as it attempts to energize the ignition rod then just clicks off and reattempt every 30 seconds or so.
Swap out the board and fires right up. No need to jack up the cables.
Have installed 2 additional CO detectors in the house.
Ordered a replacement control board in early December 2020, postal service was a train wreck during end of year holiday season due to staff shortage from COVID - took 4 weeks for the board to arrive. During all that time the quick and dirty trick of jacking the cables up kept the furnace working, I was planning on waiting til spring to change out the board if it continues to hold up.
...Until last night when temperature dropped to -20. Furnace finally gave out, wouldn't ignite and falls into constant loop of fail to ignite and reattempt. it would rapidly click as it attempts to energize the ignition rod then just clicks off and reattempt every 30 seconds or so.
Swap out the board and fires right up. No need to jack up the cables.
Have installed 2 additional CO detectors in the house.
