On Sat, 18 Dec 2004 21:11:02 +0000, tripntx
wrote:
Spent the last couple of evenings searching internet for replacement
parts, which helped me identify the parts on my G24M furnace. I also
found my circuit/control board has the updated 6K07 control board. Read
through my Lennox G24M Installation Instructions and User's Information
Manual to obtain a better understanding of the system and components.
Local dealer was willing to sell me a new control board for $260 and I
found them for $252 and $258 on the net. Decided to wait until I could
spend more time troubleshooting the system.
Finally had time today to troubleshoot my system. Removed panel, wife
switched thermostat to "heat" and I found out a lot.
1. induction blower was working properly (thanks to Bubba I know it's
name)
2. almost immediately the clicking started (nothing should happen for
the first 45 seconds, except for the pressure switch to send power to
board ignition control, when board ignition control receives power
signal from pressure switch it starts a 45 second delay, at the end of
delay the board ignition control will send power to spark ignitor and
gas valve solenoid)
3. clicking wasn't spark ignitors, but was the gas valve solenoid, gas
valve shouldn't receive power for 45 seconds
4. turned off all power, turned gas valve manual control knob to off,
removed ignitor/sensor/tube assembly to confirm ignitor type, it has
two prongs at one end (spark ignition) and one prong at other end
(flame sensor?)
5. reinstalled ignitor/sensor/tube assembly and turned gas knob on
6. turned power back "on" and called for "heat" again, gas valve
started clicking again within 2 seconds after blower started
7. removed vacuum hose from blower and clicking stopped, which proved
diaphragm pressure switch was working (considered turning off power and
ohming through switch while manualy applying vac/press into tube but
decided my wife would think I was nuts)
8. reconnected vacuum hose to blower, diaphragm pressure switch sent
power to control board ignition control circuit, which sent power to
gas valve again without waiting the required 45 seconds
9. realized something within the control board ignition control circuit
wasn't working properly, turned off power and gas valve
10. searched numerous forums looking for G24M and 65K07 information
11. one mentioned replacing or cutting off black cover from the gas
control relay and cleaning the contacts, which is on the control board
next to the 15 pin connector
12. another one mentioned checking ground wire connections
13. I decided to remove and reseat all plugs and wire connectors on
board
14. I then tilted board away from top two plastic retainers and
inspected the back of it for burnt/black spots
15. Lastly I "lightly" tapped on board relays
16. turned power and gas knob "on"
17. called for heat, induction blower started, approximately 45 seconds
later the gas valve opened and spark ignitor lit
18. selected cool, compressor came on and a/c worked
19. selected heat, furnace worked
20. selected off and selected fan "on", fan worked
21. selected heat and continued to play with thermostat settings to
turn off need for heat and then to call for heat
22. furnance continued to work
Hopefully my system will continue to work. Considering the low cost of
some replacement parts, I've decided it would be wise to keep some on
hand. I'm planning to order the following:
Furnace - flame rollout sw, primary and secondary switchs, pressure sw,
blower motor capacitor
Compressor - comp time delay 1 minute, 24v double pole 30 amp relay,
capacitors 35W comp and 5W fan 440V
Thanks for all y'alls help with fixing my system,
tripntx
Not to burst your bubble or anything but you've done nothing to
identify the problem and nothing to fix the furnace. You furnace WILL
stop working again and it WILL stop working at a most unlikely time.
Now that it is working, you might want to reflect on this time to do
your research and find a good, competent fair hvac company. Otherwise,
just get "one of everything" on your furnace and start changing parts
till your hearts content.
Bubba
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