Carrier Furnace 58MXA - Problems

DFL · 11-13-2011, 11:46 AM

Hi all,

I have a 11 year old Carrier 58mxa gas furnace. We had a brown out and then black out for about one week. I installed a generator, the furnace would not ignite (lockout, code 14). I waited to get power back, same problem.

The burners do not light at all, at start up, and goes into ignition lockout.

I've seen code 14 and 34. We hear and see it spool up, and the ignitor starts to glow for about 5 seconds, then it shuts off. Tries 2 more times, then it goes into lockout.

We reset it (turn circuit breaker off/on), and 20% of the time, we can get the burners to light and the works great, until the temperature reaches it's programmed setting, shuts off, but then won't turn back on again when the heat is needed again.

We assume it's not the flame sensor, as we're not getting any flame at all at the burners.

We've recently paid a contractor close to $1,000 dollars to diagnose and fix the problem. They said it was the gas valve and replaced it. I think I was scammed b/c if it was the gas valve it wouldn't run at all, correct? They claimed to check everything and said they cleaned it. This process with this contractor lasted about one week. To make matters worse, the contractor order the wrong gas valve and tried to install. When he turned on the system all you smelt was natural gas. He said the new gas valve was defective but as it turns out it was the wrong gas valve. Other issues involved made me feel that all they cared about was money, not fixing the problem.

Anyway, after the valve was installed the unit worked for about one day and then right back to the same issues.

Enough of my crying, I just want to fix the problem.

What could it be? Hot water heater works and so does dryer.

The ignitor lights and the nothing.

Any helpful instructions? Thanks!

yuri · 11-13-2011, 12:28 PM

Sounds like the circuit board is damaged by the brownout (low voltage) and you running a generator to it. Generators CANNOT be used with modern furnaces as they produce power which is between 56 and 62 hertz/hz /cycles and sometimes higher and lower than that. OK for power tools but circuit boards require a CONSTANT 60 hz/cycles power. Sorry.

Some of the newer ones even have a lockout feature if the hz is too high or low.

biggles · 11-13-2011, 01:42 PM

furnace might be needing a solid ground wire from it to the generator for spark ignition...even though you have 115v fed the gemerator is the power source for now but the unit has no ground...if your coming out of a switch over from the house circuit breakers with the generator running and grounded to the panel... might just be a furnace issue...

DFL · 11-13-2011, 02:13 PM

The generator has been off and disconnected prior to service. I don't know if its the circuit panel. Everything else in the house works and when I turn the breaker on and off the furnace sometimes goes. The contractor who came, said it is grounded. I don't know what is going on?

buckaroo104 · 11-26-2011, 02:54 PM

Sounds exactly like our 58MVP. Runs 90% of the time, then usually around 3:00pm when the thermostat jumps from 19 to 20C, we get four 34 errors then the dreaded 14 error.

Cycle the power to the furnace and 99% of the time it fires right back up. The strange part is that it nearly always works at the early morning heat call, 18 to 20C.

Service folk replaced the gas valve (solenoid was humming, not sure the tune...). Worked okay for 3 days then back to the 14 error at 3:00pm.

Service folk cleaned all the traps. Worked a couple days then the 14 error at 3:00pm.

Replaced the mainboard. Worked a day then the 14 error at 3:00pm.

The ignitor is next. I'm hoping.

You're not alone.

harleyrider · 11-26-2011, 03:49 PM

Quote:

Originally Posted by DFL

Hi all,

I have a 11 year old Carrier 58mxa gas furnace. We had a brown out and then black out for about one week. I installed a generator, the furnace would not ignite (lockout, code 14). I waited to get power back, same problem.

The burners do not light at all, at start up, and goes into ignition lockout.

I've seen code 14 and 34. We hear and see it spool up, and the ignitor starts to glow for about 5 seconds, then it shuts off. Tries 2 more times, then it goes into lockout.

We reset it (turn circuit breaker off/on), and 20% of the time, we can get the burners to light and the works great, until the temperature reaches it's programmed setting, shuts off, but then won't turn back on again when the heat is needed again.

We assume it's not the flame sensor, as we're not getting any flame at all at the burners.

We've recently paid a contractor close to $1,000 dollars to diagnose and fix the problem. They said it was the gas valve and replaced it. I think I was scammed b/c if it was the gas valve it wouldn't run at all, correct? They claimed to check everything and said they cleaned it. This process with this contractor lasted about one week. To make matters worse, the contractor order the wrong gas valve and tried to install. When he turned on the system all you smelt was natural gas. He said the new gas valve was defective but as it turns out it was the wrong gas valve. Other issues involved made me feel that all they cared about was money, not fixing the problem.

Anyway, after the valve was installed the unit worked for about one day and then right back to the same issues.

Enough of my crying, I just want to fix the problem.

What could it be? Hot water heater works and so does dryer.

The ignitor lights and the nothing.

Any helpful instructions? Thanks!

sounds like a main board gone gad......

buckaroo104 · 12-06-2011, 12:08 AM

New ignitor arrived today and replaced the old one. The old had a resistance of 84 ohm, the new one was 62 ohms.

So far so good 8 calls for heat and 8 clean light offs, a record! Much quieter/gentler lightoffs as well, no more "whoomp"s.

Hoping this is the fix, touch wood.

Great site!

buckaroo104 · 12-09-2011, 06:30 PM

3 days and not a single missed ignition (one night was -20C). Seems the problem was a tired ignitor. Only difference between the two was 8 years and 22 ohms.

Great website!