We speak HVAC so you don't have to
CONNECT with us!

our tools and detailed reports
can help you choose the best
furnace, boiler, heat pump or
central air conditioner.

See all questions

My furnace wasn't working so my ran the test and it showed "reverse polarity" how can that be we have had a running furnace for 12 yrs and we have never touched it. Anyway he bought a new control board and installed it and it still didn'

Post created: 2013-04-13 Type of Equipment: Furnace Views: 130

This question was created on the page: https://www.furnacecompare.com/furnaces/bryant/340mav.html.

On 2013-04-14 JB wrote:

Generally this is a sign of a bad control board. Perhaps there is an issue with the transformer or maybe there is a problem with the new control board. I have also read that if there is fluctuation in the power coming into the house it can fry a mother board so it could be something to do with the source and not the furnace.

This is a tough one to provide advice on because it really does require a certified HVAC tech to be on the scene and run some diagnostics. Many furnaces have an error code, which is either a couple of blinking lights are an LED display, that advices to switch two wires to check polarity, but this can be a dangerous thing to do and is not recommended.

Sorry to not be of more help.

To keep legal happy, let me just say that I am not an HVAC contractor, and you should never even look at your furnace without having a qualified, liability accepting HVAC contractor present.  To keep sales happy, let me just say that you can find an HVAC contractor that's happy to take your money here: http://www.furnacecompare.com/perl/find_contractors.pl.

Your Answer

Copyright 2002 - 2016 furnacecompare.com