Question about Heating & Cooling

1 Answer

High limit switch open- but only faults in night and extreme cold

I have an Armstrong Air furnace that is not blowing hot air. Noticed the LED light is flashing four times, which, according to the alarm code means I have a high limit switch open. Turned the furnace off and back on but that didn't do any good. Strange thing is, it only only faults in night and extreme cold. Already replaced air filter ans reset entire system. problem still persists.

Posted by on

  • 2 more comments 
  • tonalligroup Jan 02, 2009

    I drained but the problem persists. There was less than 1 cubic in water in the line. Any other suggestions?
    Thank you

  • tonalligroup Jan 02, 2009

    I drained but the problem still persists. There was a bout 2 fl oz of water in the line. Any other suggestions?
    Thank you

  • tonalligroup Jan 11, 2009

    No, it does not have any other listings. It has since been serviced by a HVAC technician and he replaced the high high limit switch. $80 including parts and labor. Thank you

  • jmrfxit May 11, 2010

    does the code four have any other listings? (secondary limit,or flame rollout)


1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Expert
  • 242 Answers

Hello , I can try to help you out on this one , It sounds like what is happening is that your exhaust vented up is condensating from the heat in the pipe and the cool in the attic or wherever the exterior of the exhaust pipe travels. It is very common because your exhaust/flu pipe is not insulated.
To fix this issue you must drain the water/condensation from the small 5/16th hoses in front of the blower assembly , just pull them loose and angle them downward to drain. This should fix the problem if this is the problem.
Let me know how it turns out or if you have anymore questions. Phil

Posted on Dec 31, 2008

  • Phil Brantley
    Phil Brantley Jan 02, 2009

    If the unit is still giving you the same problem and code-reset the unit turn on the heat and while the ignitor starts glowing tap on the gas valve soft then harder , the gas valve is in front of the blower assembly and may have a on/off toggle they are normally 4" by 4" square and the gas line feeds right into it. These valves are known for sticking and if you get it going this way or not its your problem , somtimes the tapping works but only temporarily .

    You will need to order a gas valve assembly for your model armstrong. They are not hard to replace , you need a cresent wrench and a pipe wrench and gas line thread sealant. Getting that one out will be most difficult , turn the gas off before the unit of course. Check your connections when finished by putting soapy water on them. To get the valve you may find it on line or your local A/C warehouse. If you have any questions let me know.



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

My gas furnace is working but the led light will not stop flashing, is it suppose to keep flashing.

A steady heartbeat on the circuit board USUALLY means normal operating condition.

Mar 29, 2015 | Heating & Cooling

1 Answer

Furnace blowing cold air

Turn power off & on again. Watch to see if it could be the hot surface igniter if you don't see it turn bright orange. If it goes straight to blowing cold air, then normally it is a limit switch open- mostly manual reset - thermal disc-located around flame rollout.

Dec 20, 2013 | Ruud RGTM10ERBJS 100K BTU 95%...

1 Answer

Lennox lb50527cc

high limit switch, no proof of flame.

Oct 27, 2013 | Goodman Heating & Cooling

1 Answer

Intertherm mmha070

Hi, did he bypass the high limit to see if it was bad? Sounds like you are getting false codes and you have a problem in your module or main board, which ever you have. The way it is acting, saying the high limit is open but the tech says its not, I would change the board.

Nov 14, 2011 | Intertherm P3RA-048K Air Conditioner

2 Answers

Why does the led on my furnace control bd flash three times

Hello, this indicates a open limit switch. A limit l switch will open when the temp in the heat exchanger gets too high and this switch shuts the Furnace down for safety. Usuaully a dirty filter, weak blower motor, dirty blower wheel will cause a limit switch to open.

Nov 12, 2011 | Heating & Cooling

1 Answer

My goodman furnace, model number GDS80703AXBB has a red light bllinking 4 times and the panel says it means open high limit... how do i fix this?

Hello, a limit switch will open when the furnace gets too hot, the switch senses that the temperature is too hot and shut down the furnace for safety. Uusally a limit switch will open because of lack of airflow across the heat exchanger, this could be due to a dirty air filter, dirty blower wheel, or the blower motor itself is not running at the proper speed. I hope this helps.

Feb 16, 2011 | Heating & Cooling

1 Answer

My carrier 58sta furncace is blowing cold air constantly

Code 33 is "limit is open or flame switch is open"
FIRST make sure the filter is clean. Turn off unit then turn back on.
if it works but then later gives you a 33 code then you might have a dirty a/c coil (if you have a/c) that will cause the limit to open. 1st try that

Mar 21, 2010 | Carrier Heating & Cooling

1 Answer

Gas valve lockout

It means that the furnace isn't igniting and for safety the control board is preventing the gas valve from opening. Turn off the power to the furnace for a few seconds then observe what the furnace does in heat mode. Some furnaces will run the blower for a minute after you power it back up. After that see if the furnace tries to come on. If you are still getting the code then one of you high temp limit or roll out switches has tripped. Now is the time for a service tech. Make sure that you check you filter and air flow too. Low air flow means the furnace may be over heating.
The other thing is the hot surface igniter. Look closely at it with the power off. Do you see a white spot on the element or a crack. If so the HSI is bad. It's an easy replacement but DO NOT touch the carbon element with your fingers and be very careful handling it as it is EXTREMELY fragile.

Mar 17, 2009 | Carrier 38BRC048 Air Conditioner

1 Answer

Goodman Dependable 92 blowign cold air only - no heat

blowing cold air on this furnace usualy caused by high limit trip, or flame roll out. the first one, (high limit) is from insf. air flow. (blocked filter,bad zone damper?
The second,(flame roll out) caused by bad heat exchanger,blocked vent.ect.

Jan 09, 2009 | Heating & Cooling

4 Answers

High limit switch open on armstrong furnace

If you know where the high limit switch is you can always cut the two wires and wire them together causing the limit to close. But what you have to watch out for is why the high limit is not closing. That means in your return air either you have a dirty return air duct, dirty filter, or you don't have all your registors open to allow the heat to escape the heat exchanger. Just watch over riding the system. The high limit switch should either be on or behind the blower, in the middle of the system right under the heat exchanger. any other questions about hvac just ask.


Mar 23, 2008 | Heating & Cooling

Not finding what you are looking for?
Heating & Cooling Logo

Related Topics:

288 people viewed this question

Ask a Question

Usually answered in minutes!

Top Heating & Cooling Experts


Level 3 Expert

2116 Answers

Dan Webster
Dan Webster

Level 3 Expert

8205 Answers

Donni Steen

Level 3 Expert

659 Answers

Are you a Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides