lennox furnace out of sequence, gas

[tripntx]

Lennox Model G24M3-75A-4

When selecting heat, fan comes on with heat demand and ignitors star immediately clicking. This shouldn't happen. Ignitors should wait 4 seconds before clicking. It'll keep repeating until locked out.

When ignitors start clicking when blower starting, I'll move temp dow and after turning system on/off moving temp up/down several times, mak that numerous times over a two hour period, the system will finall work. Meaning, fan comes on and after a 45 second delay the ignitor click and the system works.

Furnace will work normally until termostat manually set to cool. The problem starts over again when the need to return thermostat to heat.

Other symptoms are: It'll display solid diagnostic lights indicating control board failur after a few attempts, but not at first; set fan from auto to ON and fan doesn't work, just makes a sof clicking noise, control board will indicate board failure; Air Conditioner works everytime when placed to cool.

What/which parts do I change first?

What is causing ignitors to click at same time as blower starting?

Why doesn't my fan work when set to ON?

Please help

-- tripntx

[Bubba]

You obviously dont have a clue how the system works. Thats ok. You shouldnt. Thats why there are repair techs take care of it. No one can diagnose it over the net. Get it looked at by a qualified technician. You'll most likely save a lot of money in the long run. OR, you can just change parts until you get it right. Note: Lennox parts are very costly compared to others and they are almost impossible for the homeowner to purchase. Bubba

[Alice Beach]

I agree with bubba, but, first thing to check is your supply voltage,common and ground. If you find that hot ( L1 ) to common is not the same as ( L1 ) to ground that is your problem. Have had this happen, Lennox is very ground criticle. Found that L1 to ground was 100 volts or less and that was the problem.

[tripntx]

You're right. I don't have a clue as to the role individual component

play. I do know, when my heat is working properly:

1. evacuation blower starts for 45 seconds
2. after 45 seconds, ignitors click once or twice and burners light
3. air handler blower comes on to distribute heated air

Currently, evacuation blower and ignitors start at time, burner doesn' light. I do not mind replaceing the most likely components, becaus local technicians around here will do so as there means o troubleshooting. I'm just trying to cut out paying someone else labo to sub in components until it works

-- tripntx

[Bubba]

Evacuation blower? That would be an inducer motor assembly Igniters click? Spark ignition may click. An igniter (glow coil) just glows. Pilots burn. Air handler blower? So what exactly do you have? An air handler or a gas furnace? I havent seen an evacuation blower in an air handler. Like I said, you most likely wont be ablte to get Lennox parts. They have their own tight little network. If you do, you will pay dearly for them. Tell me this and Im being serious as a heart attack. Why on this freakin earth would you pay a technician to replace parts (or his labor) until he guesses the right one? Now if he wants to replace them all one at a time until he gets the correct one and then charges you for that part only plus a diagnostic fee of some type, then that would be fair. Its a stupid way of fixing a furnace and it involves no skill at that point but HEY, its your dollar. All the more reason to call a company that charges "Flate Rate Pricing". You get quoted a service call/diagnostic fee before they even show up. Then he can diagnosis and replace parts until his hearts content. You are only going to pay for what it takes to fix it AND you get the quote BEFORE it gets fixed. If he quotes you a repair too high that you cant live with, you pay the diagnostic and show him the door. How simple can that be? ....and again, from your description and terminology, you really should leave your furnace alone and let someone look at it that knows what they are doing. Bubba

[Matt]

I was broiled pretty good a few years ago over in alt.hvac.... and in that time, managed to find two HVAC techs in that forum I respected. One was Bubba, the other was Paul.

Tripntx - as an owner of a Lennox furnace, I'm BEGGING you to take Bubba's advice. Mine is a G27M, and has gone out EVERY fall since I bought it 4 or 5 years ago.

EVERY part has been replaced... and I MEAN EVERY PART, each visit done by a Lennox tech. I'm not making this up....... the ONLY original part left on the furnace is the frame, and I expect it will probably fail too.

Out of the 12 or so techs that have visited my house - I'd say 2 were competent. The rest were parts changers.

My point is that Lennox makes CRAP, and the companies that service them can't even really keep up with the crap level.

Call a service tech, and WATCH THEM. Don't be a dick, but be aware of what they are doing. You'll know pretty quickly if you got a good tech or not.

Even if you get a "parts changer".... so what - just keep track of what they do, and you'll know what you should be charged for.

By swapping parts yourself, you are simply setting yourself up to make the situation much worse. I can virtually GUARANTEE that you will swap the wrong part, and as Lennox makes such CRAP it's likely you will break something else in the process. This isn't a slam against you - it's just that not even Lennox repair parts are fully swappable..... on the third installation of a new control board, they finally put in some sort of "upgraded" model. This WAS NOT a swap out situation - wires were cut from connectors and routed to other boards, new connectors were installed on other wires... etc.

Take Bubbas' advice man - DO NOT attempt to repair something that can kill you and your family in your sleep.

[Robert Worcester]

Ditto

Listen to what Bubba says.

Piddlin' around with your flivver in the driveway can be a good source of stress relief, fun, and you can save money on a mechanic's labor.

But working on your own gas heater? Don't do it. The life you save may be your own.

Robert

[tripntx]

Thanks to everyone who replied.

Evacuation blower? That would be an inducer motor assembly. Thanks for providing proper name.

Igniters click? Spark ignition may click. An igniter (glow coil) just glows. Pilots burn. I do not have a constantly burning pilot, maybe I'm hearing contact within a switch causing the clicking sound.

Air handler blower? So what exactly do you have? An air handler or a gas furnace? I havent seen an evacuation blower in an air handler. The fan which pushes both heated & cooled air through the ducting i housed within the same horizontal case as the furnace. One end i connected to the return filter box. Other end is connected t evaporator coils and then to ducting for ceiling vents.

Tell me this and Im being serious as a heart attack. Why on this freakin earth would you pay a technician to replace parts (or his labor) until he guesses the right one? We're busy at work. Leaving home at 0500 and returning home at 193 hrs. That leaves only Saturday or Sunday to have a Tech at the house which they charge dearly for after hour support. Unfortunetly, I can' take leave for a couple of weeks, other than Federal Holiday's. So, m wife would be there during business hours but wouldn't enter the garag with him. I wouldn't have a clue as to his troubleshooting steps.

The first summer after buying our home, the fan went out. Comp came on then shut off because the fan wasn't working. Called Lennox dealer wh installed system, told it would be 2 days wait, TX coast was 95 humidity and temp was over 96. I crawled in the attic, opened up th case, studied the wiring, bypassed the capacitor and hard wired th fan, flipped pwr on, and fan didn't work, thus eliminating capacitor a problem. Removed fan, took to dealer, paid $15 handling fee (was unde warranty) and they gave me a new fan, which I then installed an haven't had a problem with it since.

Two summers ago, Comp wouldn't work, but inside fan would work in O position. I open the side panel, decided to remove the relay contac assembly (blk plastic with numerous contacts), took it to a loca electrical supply warehouse, matched it, paid approximately $6 installed it, system worked.

Last summer, Comp wouldn't work properly, removed a time delay assembl (mounted near relay contacts), took it electrical warehouse, pai approximately $20, installed it, and the system worked again. I can' remember what I set the time delay at, but it was in seconds.

Every spring I house out my comp coils, and then have the dealer visi to connect gauges and inspect/service system.

I repair fighter aircraft electrical systems for Uncle Sam. I'm scare off household electrical measurements because I only deal with 22 gaug wires carring DC. But, principals of using a multimeter to chec resistance, amps, and volts are very similur.

Thanks for the advise, I'll attempt to take leave early one afternoo and schedule an appointment with a Tech

-- tripntx