Question about Heating & Cooling
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. How do I find and manually close/reset the high limit switch??? Thanks!
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.
Posted on Jan 17, 2009
You need an ohmmeter. Start checking all thermal limit switches
and fuses. Remove one wire when checking and also turn voltage off to unit. It could be a resetable switch, start pressing all the pop up buttons on the switches.
The cause could be simply - dirty air filter or a blower assy problem, or dirty flue vent, or induce draft fan problem.
Posted on Mar 23, 2008
I have an Armstrong high efficiency 90+ Condensing Gas Furnace. The Blower works on Cool, but not when the Heat is on. The LED flashes 3 times: Fault is Pressure Switch open with inducer on"
Where is the combustion blower? Is this an easy fix?
Posted on May 12, 2010
The limit switch is one of several built-in safeties designed to protect the furnace and prevent a possible explosion. Rule # 1, i.e. don't put jumpers or do any other things that you don't fully understand as it is extremely dangerous to play with furnaces. Remember, you are not a certified HVAC mechanic. Rule # 2, i.e. read the manual and follow simple steps such as find any blockages, open closed registers, etc. Rule # 3, i.e. if all the above doesn't help, don't be a frigging idiot and call a professional !!!!!
Posted on Dec 29, 2009
I had the same problem. The furnace was cold but it get 4 blink failure code right after the fans were on. I traced the Orange cable that come out of the High Limit switch to the connector to the control board. When I push the cable from side to side right at the connector, I heard relay clicking and the 4 blink failure code was gone. I put two toothpick and jam and push the cable to one side and the furnace fired up. I will fix it later. At lease I found the problem as simple as with the table connector.
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Posted on Jan 02, 2017
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