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Armstrong air ultra v tech 80

Fuse on pcb blows when activating air conditioner. heater works fine. i have 27.5 vac from transformer to pcb

Posted by Anonymous on

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Posted on Jan 02, 2017

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SOURCE: Heater blowing out cold air

Yes you could have a bad overload on the heater element which is fairly simple to fix. To test for this pull the heater out and get an ohmeter set it to continuity and check the continuity first through the entire heater element then if there is none pin point the overloads and check to see which one has no continuity.

Posted on Dec 23, 2007

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SOURCE: Carrier Thru-Wall Heater and Air Conditioner won't heat
Here is some troubleshooting tips.
Also service available.

Posted on Feb 25, 2008

  • 306 Answers

SOURCE: armstrong ultra sx 80 furnace

Flame sensor could be dirty. It is located right beside the last burner looks like a thick piece of wire. Take steel wool and gently clean the probe 4 or 5 strokes is all it will take to take off the carbon build up off. Lets eliminate this item and see if it clears up okay. ken

Posted on Dec 21, 2008

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SOURCE: armstrong ultra sx 80 furnace

You have a dirty flame sensor. Look at the very last burner and you will see a wire going to a ceramic sensor and it looks like a thick wire. Take some steel wool or fine sandpaper and clean the surface off and it will work like a champ.

Let me know how it goes ken

Posted on Apr 15, 2009

  • 127 Answers

SOURCE: Dometic 57915.531 Air Conditioner Blows 3 amp fuse in control box


The three amp fuse is installed in the board to protect from shorts or overloads created by disconnecting or reconnecting components when DC power is still connected to the system. If the fuse is blowing, then you more than likely have a short in the 12VDC system between the control unit and the thermostat.

1. Pull the cover off of thermostat and remove the +12 (or +7.5 depending on the model) wire. Access the other end of the wire in the AC compartment. Using an ohmmeter, touch the end of the wire at the AC with one lead and touch the control box with the other (or any ground source). If you get a reading other than OL or Infinity, then that wire is shorted out in the wall somewhere. If not, repeat the steps for the rest of wires except the ground of course. If all of these wires appear to be fine, you may need to take it in for some more extensive troubleshooting.

Hope this helps,


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Posted on Jul 04, 2009

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1 Answer

Where is the low voltage 24 vac transformer located?

The transformer is located in the furnace. You might want to check to make sure the furnace door is on correctly brcause theres a swich that will open for safety . Also some have a fuse on the solid state board.

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My house was struck by lightning most of all my computers and tv's and phones are no working and my ac is not coming on at all. What happen to my AC unit

Hi and welcome to FixYa, I am Kelly.

The main Preinted circuit board (PCB) most likely has had a failure of the small PCB transformer. This is the most susceptable component (PCB transformer) in the Air Conditioner. Within the last 60 days I have personally experienced the exact same symtom. I replaced the PCB transformer and 1 diode on the main PCB of the air-conditioner and my AC unit is working fine. Unless you can find a source for the transformer your only option is to replace the PCB (Board).

Finding the exact transrformer for the PCB can take a very long time. It iwll look similar to this one:

If you have home owners insurance ALL STATE and State Farm often cover this type of damage. It is worth the time to find out if you are a home owner.

Thanks for choosing FixYa,

Sep 13, 2011 | Frigidaire FAC085M7A Air Conditioner

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I have 1990 Armstrong gas furnace Ultra III 80, Model EG6G75dc8-4 .\r\nWhen I turn thermostat up , furnace comes on, burners come on, motor that I believe turns blower turns on but i AM NOT GETTING AIR...

have you checked your filter yet? the other thing to check is open the fan door and jumper the door switch,if there is one, and turn the furnace on. is the fan blowing air now?

Mar 22, 2011 | Heating & Cooling

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We have an Armstrong Ultra SX 80 furnace. I can't seem to find the filter on it. Does it take filters and if so, where should they be installed?

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Sep 26, 2010 | Heating & Cooling

1 Answer

I keep blowing the control transformer when I turn on the A/C. The system works fine when I turn on the heater. When I try to turn on A/c nothing turns on before control transformer blows.Jim...

First thing I would recommend is to go to the closest auto parts store and get an inline car fuse folder and some 5 amp fuses. Connect this to wire that comes off the transformer and goes to R. That way you will only blow fuses instead of transformers.
I will assume this system isn't a heat pump since it runs fine in heat mode. If it is, please let me know. Also, I will assume there is no circuit board outside, but let me know if there's one.

Go out to the condenser and remove the Y wire from the contactor, then try the system in cool mode. If the fuse blows, you have a short in the low voltage wire between the air handler and condenser and will need to find it, cut it out, then re-splice. If the fuse doesn't blow, you will likely need a new contactor.

Mar 23, 2010 | Ruud UBHC Air Conditioner

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Armstrong ultra sx 80 furnace starts up and runs and then the gas shuts off for a few seconds and then lights backup and causes a small backfire my Ultra sx 80 furnace will ignite then immediately turn...

You have a dirty flame sensor. Look at the very last burner and you will see a wire going to a ceramic sensor and it looks like a thick wire. Take some steel wool or fine sandpaper and clean the surface off and it will work like a champ.

Let me know how it goes ken

Apr 15, 2009 | Heating & Cooling

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