To Replace the Board...

[mwpiper]

...or not to replace the board. That is the question.

I have a Carrier furnace, model 58PAV090-14, installed fall of 2000 (11 1/2 years old) Air conditioner works. Furnace does not. Weather has been cooperative. I've been able to make due for the past week and in a week or two probably won't need the furnace at all for another six months, so I'm in a position to futz around with fixing this.

The first symptom is the red LED is flashing continuously. It is normally on steady, no flashing. It is not providing any codes, just the rapid flashing. The legend on the door panel states the rapid flashing indicates reversed polarity in the 115V AC. Not sure why this would have changed spontaneously after 11 years. I have checked that the hot line is hot and the neutral is not, checked ground and reversed the leads to the control transformer following recommendations on another forum with no success.

Yes it's getting input from the thermostat. The thermostat can turn on the air conditioner. Also, if the furnace power is turned on while receiving Heat command from thermostat, the main blower turns on for 90 seconds and then turns off. It does this. Problem is that after the blower turns off, it should begin the ignition sequence. Nothing happens. No power (measured with multimeter) is provided to the inducer motor. And if the inducer motor doesn't turn, nothing else is going to happen. I tried to tap the relays to see if they could be freed up to no avail.

Physically, the control board (no. 1012-940-J HK42FZ009) appears undamaged. No sign of burned conductors. Fuse is still intact. However, some of the exposed component leads are covered in green dust that looks like copper oxide. Is that indicative of something?

Thirty years ago I used to work on multi-megawatt induction furnaces as big as my living room. Now I'm staring at this furnace the size of a big suitcase wondering what to do next (or dithering because I know but don't want to cough up the money)

Is there something else that can be checked or should I just change the board and be done with it?

[Shophound]

The component leads covered in green dust...offhand I'd be looking for moisture getting on the board somehow. Either a leak in the roof, water coming down the vent stack, or moisture condensing inside the vent stack and finding a way to drip on the board somehow.

If there's no moisture involved, are these oxidated areas electrical connections, such as where the thermostat wires connect to the board? Could be loose connections have contributed to oxidation (heat).

[btuhack]

... but don't want to cough up the money

If you cough in the direction of a licensed contractor, you'll have a safe, reliable furnace with a repair warranty. It would already be done and working.

[mwpiper]

Control board is located in blower plenum at bottom of unit. Most likely source of water is frozen condenser coil that caused condensation to run all over the floor. This happened a number of times when the unit was new because the original condenser coil leaked refrigerant. No refrigerant leaks since that was replaced. Subsequent freeze ups involved plugged filters. Have established that anything that creates significant amounts of dust can will wipe out the filter in a day. Consequently, haven't had a freeze up for a long time.

If I coughed in the direction of a contractor, they would probably get both lungs. I recently paid a licensed contractor $ for a $ thermostat. Don't really want to find out what the markup is for a $ control board. A series of unfortunate events, besides the furnace, has bones sticking out on the piggy bank and we still have to go halfway across the country in May to see the last kid graduate and come home to join the ranks of unemployed college graduates. Licensed contractors are great when money is no issue. But sometimes you have to decide if you want to pay to put their kids through school or your own and easy, timely and convenient usually gets sacrificed as a result.

[beenthere]

Prices are not allowed.

[llskywalker]

From the sound of it, the board needs to be replaced. It's possible that the realy for the heat sequence failed inside one of the covers and you can't physically see it. Get a board off the internet that most likely doesn't have a warranty or call a licensed tech to replace and have a warranty.

[DLZ Dan]

Not for nothing, but you're talking to a bunch of licensed contractors on this site.
We paid for our education too, you know. What btuhack was trying to say is that we get paid to make sure it's fixed right and any good contractor would come back and take care of it if it wasn't fixed right. Hence the warranty.

I'm a father of 3 myself so i know stuff is tight right now and you don't was to spend money where it may not fix the problem. I just think it would be one less thing to worry about if you have a pro fix it.

Unfortunately this is not a DIY site so if you take it upon yourself to replace the board, then you do it on your own volition.

[btuhack]

What btuhack was trying to say is....

Dan, you're gonna make a great mother in law for some lucky young fella one day.:whistle:

[timebuilder]

Control board is located in blower plenum at bottom of unit. Most likely source of water is frozen condenser coil that caused condensation to run all over the floor. This happened a number of times when the unit was new because the original condenser coil leaked refrigerant. No refrigerant leaks since that was replaced. Subsequent freeze ups involved plugged filters. Have established that anything that creates significant amounts of dust can will wipe out the filter in a day. Consequently, haven't had a freeze up for a long time.

If I coughed in the direction of a contractor, they would probably get both lungs. I recently paid a licensed contractor $ for a $ thermostat. Don't really want to find out what the markup is for a $ control board. A series of unfortunate events, besides the furnace, has bones sticking out on the piggy bank and we still have to go halfway across the country in May to see the last kid graduate and come home to join the ranks of unemployed college graduates. Licensed contractors are great when money is no issue. But sometimes you have to decide if you want to pay to put their kids through school or your own and easy, timely and convenient usually gets sacrificed as a result.

While we all have sympathy for you, the rules here prohibit giving DIY advice. With your previous experience you could probably do the repair, BUT, since this is an open forum, this thread would become a part of what is essentially a searchable database that is indexed by search engines. That makes whatever we would yell you, a guy who could do the job safely, a case of actually telling the entire English speaking world, and they may not do it safely.

And we can't have that.

And, for the record, I have about five things I would check BEFORE I would buy a board.....

[DLZ Dan]

Dan, you're gonna make a great mother in law for some lucky young fella one day.:whistle:

Smart A$$

[catmanacman]

:callpro: Mr repairman my furnace is broke come fix it

[qawsed]

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Have a nice day.

[hvacvegas]

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Tough.

Next time leave your purse at home.

[Joehvac25]

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Those type of hacks don't partake in a website like this that will further there knowledge and experience. If you can't afford to maintain your home maybe you should rent. As timebuilder said if we replaced a board every time the heat didn't work there would be problems.


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[beenthere]

qawsed, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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Your post has been deleted.
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[pacnw]

So what are the "experts" afraid of...a little competition?

NO!!

No one here apparently wants to (or is allowed to) offer or ask for diy help( read the rules before you post on a site or get offended by someone pointing out you are in violation of those rules), and no one is allowed to share what cost experiences they have had? It seems this industry has the same level of transparency as politicians!

prices vary from location to location, say like the cost of gas does. so if I told you it cost $150 in my area it does not give you an solid basis as to compare in your area. labor rates, insurance, mark up, hourly or flat rate, travel time and many other factors are also involved.

Seems like someone is trying to masterfully keep control of an industry and keep customers in the dark.

Smart buyers are informed buyers, and attitudes like I am seeing here, is why the service industry gets a bad rap every time?

Last questions to the "experts"...ever convince someone to buy or replace a part they didn't necessarily need to just to make a few extra bucks... because those of us who are informed, knows it happens a lot in the hvac world.

NO! NEVER! NOT GOING TO HAPPEN!

Have a nice day.

one can be informed, but still be an idiot when making a decision. we have many people who come into our shop buy parts until they finally fix it and many times spent much more than if a tech had come out to fix it. we don't just fix the problem, we also ensure the safe operation of the equipment.

do you know why that part failed or is not functioning as it should?

do you know what a failed heat exchanger looks like?

many things should go into a repair, not just parts replacement.

the service industry gets a bad name because cheap, unappreciative, uneducated individuals think there is nothing to the work. they can pay X for the part online so that is what they should pay a person to fix it, not taking into account those things I listed prior and others.

so, Have a nice day!!:putergreet: :putergreet:

[AYservicetech]

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[jpsmith1cm]

AYservicetech

This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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[54regcab]

The other thing is if you buy the board and replace it and it DOESNT fix the problem you are out he money. A contractor will determine if the board is actually bad, and if it doesn't fix it then you aren't out the money for the board.

[precision hvac]

Ahhhhhhhhh
This thread is from April guys. I'm betting it's been taken care of by now.

[54regcab]

Ahhhhhhhhh
This thread is from April guys. I'm betting it's been taken care of by now.

Or maybe its getting cold again...