OT: Furnace Problem

When I got up to go to work yesterday, the furnace was working fine. By "furnace," I'm referring to the LP gas central heating unit in my utility room that heats the house. Brand name is Bard...which, I understand, stopped building furnaces in 1997. Mine is a 1996, model MPG100D48C.

In the past, I'd had a LOT of problems with the Honeywell controller...specifically, burning out the integral fan relay. A couple of years ago, Honeywell updated the original style controller with a new model, number ST9120U, and I'd not had another problem since...after having to replace the old style controller every 8 to 14 months after the first one went out.

When I got home from work yesterday evening, the wife told me that the furnace wasn't working. This time, the diagnostic LED on the controller isn't on at all...much less flashing a code.

Checked the LP tank...I have plenty of gas. [That wouldn't stop current from getting to the module anyway...but I figured someone would ask anyway.]

Checked the breaker...it's a double breaker in a single slot, and both tabs are marked "20"..and the breaker wasn't tripped. Flipped it off and then back on anyway; no difference.

Where the electrical power enters the furnace itself, there's a toggle switch and a 30-amp screw-in fuse. Flipped the switch off and back on...no difference. Checked the fuse...not blown.

And before anyone else asks, there is no "reset" button that I can find anywhere on the furnace...and, God knows, I've looked for one.

No wires look as if they've overheated.

SO...any of you furnace gurus out there have any ideas where to start? I can't afford to replace the furnace yet again...even though another "better" brand would probably be a wise idea, once I do get some money. I hate to decide that the module is the culprit, when I can't determine that the module is even getting any current to begin with...and a $100+ module that may not fix the problem is out of the budget anyway. No sense in throwing parts at it, unless I know it's going to fix it.

And of course it's a holiday weekend, so anyone who MIGHT come out and look at it for me is going to charge me "out the backside" just for "inconveniencing" them.

Any actually helpful ideas would be greatly appreciated.

Seems you're leaning towards the control side of it, but have you checked the igniter, that inexpensive part that goes bad like on natural gas furnaces, I know its good to keep spares of those around.

If I have no power to the control module, why should I suspect the igniter? Logically, I would think that it's the controller that tells the igniter when to fire, and not the reverse.

But thanks for responding anyway.

1-switch on the blower door due to door being ajar
2-inline fuse hidden in a bundle of wires going to that board, had to cut cable ties and seperate wires. thought I had a broken wire at first

Are you able to check to see if there is voltage going to the control board with a voltmeter? Should be 24V.This sounds like a either the board is junk or the power is not getting to it. Can you read the schematic to see where the internal fuses/safeties are if it has them? I worked on bard package units years ago but I had the wiring diagram to work from.I tried googling it and did not come up with one.
A list of things ; Safeties, fuses, thermostat, transformer not getting power, tranformer not delivering power, loose wires, If it has the honeywell smart valve it could be the connections however that is after the controler I believe. Just trying to list some things to check.

You need a voltmeter. From your post, you don't have any idea if you have power or not.

Should be some tabs on the board where black wires are connected. Check between there and neutral, should have nominally 120 volts. If the board is in the blower compartment, you will need to lock on the blower compartment door switch while testing for voltage. (piece of tape usually works). If no voltage at the board terminals, work your way back to the breaker panel, checking at each switch and/or junction boxes.

If you have 120 volts at the board terminals then look for a fuse on the board itself. These are normally an AGC type automotive fuse, 3 to 5 amps. If no fuse or the fuse is not blown, it is most likely the board.

Can only help you by telling of my past experience , don't know if it fits your particular case but something you can check. Mine was doing all sorts of stupid things. Hard to diagnose when problem changes. Knew it was electrical though. Took out what some call "module" just a printed circuit board. Made who knows where. Under a magnifying glass could see 3 small solder connections that were burnt from arcing. The junk solder had cracked and sometimes connected and other times not and with 3 of them acted different each time. Took it to work and re-soldered them and cured the problem. That's been 3 yrs ago , still works perfect. What led me to this was a similar problem with a '99 Suburban w/s wiper chugging/stopping problem earlier. Same deal , a small circuit board ("module" to you hi-tech guys)on wiper motor had same problem. Fixed it same way along with 3 others at work from guys with GM pick-ups/Tahoes etc. Worth a try I would guess. Let us know what fixes it. RB

Just because the led isn't on doesn't mean there is no power to the board. They can fail so you need to check that with a meter. You need to verify the line voltage with a meter. Check at the breaker first & the move to the next junction checking every point all the way to the board. If the hv side is good check the low voltage starting at the thermostat. Turning the furnace off at the thermostat and then back on reset's them. Just for grin's turn the furnace off at the thermostat. Have the better half turn it on when you've had time to get to the furnace. Lean in and listen for the click that tells it to fire.

Check out the ssu switch the are know to go bad been doing heat and air work for yrs ssu switch with the fuse on it. check the door switch to and some of those board had fuses on them. look like a car fuse

Those Bards are famous for the control board going bad (which you know) but you gotta do some testing to see why you aren't getting any power. Doesn't matter which end you start at, I always start at the controller, then work my way to the panel. If you have power at the controller or access door switch, bad control module.

Check the breaker they do go bad,thats where I would start , get a test light or meter.

Shut the power off to the furnace for about 10 to 20 seconds and turn it back on. I paid $75 for a service charge for the service man to do just that. Furnace is still going after two years.

My Ruud furnace is on NG and it quit shortly after it was installed. Found a blown fuse cause by the wire being pinched and it shorted out. Called the installer and he came and fixed it. That was 16 years ago. My neighbor and my daughter both have Rheem NG furnaces. They had a burnt out ignitor I bought a spare as they're not that hard to check and replace. My neighbor was charged $200.00 not bad when you're freezing. Hal

Google up Bard repair. bard parts, Bard troubleshooting. Get some factory tips?

Bard I had would occasionally quit. Had to pull off a clear plastic line & blow or suck (forgot which) on the line to pop a diaphram that controlled a switch & furnace would come on for another couple of months. Then one time it wouldn't come on & go the the procedure again.

Starting at the Breaker Panel, with a Meter check your lines, switches, fuses, etc. . Go to the last KNOWN point that you have power (just because a breaker, switch, fuse, line, "looks" good, don't ASSUME that it has power until you have actually checked it with a Meter), then start checking the INDIVIDUAL LINES for CONTINUITY (IMPORTANT: TURN OFF POWER AT THE BREAKER BEFORE CHECKING CONTINUITY). You can use either the "buzzer" type continuity tester or an Ohm Meter to check for resistance. Some companies are installing a "Fusible Link" as a safety feature to protect the Controller Circuits instead of an actual fuse. A "Fusible Link" looks like an ordinary wire only it's just slightly larger in diameter, and when one of these "pops" there is NO outward appearance of the line no longer conducting power.

Good Luck, Hope you find it SOON!

Over 40 years ago, I worked my way through college as a HVAC mechanic working at Bethlehem Steel in Burns Harbor. It's hard to trouble shoot something over the phone. Even harder if you don't have a VOM meter. Next to impossible if you can't get replacement parts.

I'm retired and to supplement my income, I have rental properties. All of them are converted to simple electric baseboard heat. No service calls, no filters to change, no fan motors to change, brain boxes going out. In 40 years, I've had to replace 2 thermostats. One stuck in the on position and the other blew off the wall after a kid stuck a paper clip in it.

Prior to converting over to total electric, I would get phone calls all hours of the night with furnace problems.

I insulated all my places, new windows, doors and the bottom line is Keep It Simple, do yourself a favor and go with electric. May be a little more expensive, but in the long run you won't have any problems to speak of. All my tenants love it and so do I.

I put heaters in every room, however a well insulated 1500+ square foot home can be heated with just two 8 ft heaters.