The fan in my central air unit will not turn off. Any suggestions?

Question

We have replaced the circuit board and relay. Please email me or respond with anymore suggestions.

Answer 1

Sit down with the wiring diagram and follow the path of the blower.

I wish that you would have done that before you started replacing random parts,hoping that would fix it.Study that schematic.You'll figure it out.Good luck.

Answer 2

check your fuse! It is usually located in the garage or basement, and it could be blown. If that is the problem, it is a quick easy fix

Answer 3

Is the t-stat set on auto or fan on? If it is on fan it will run forever. Check this first. Next  pull the cover off the t-stat remove the green wire if the fan stops the t-stat is  bad. After trying these items and it still runs you may have a short in the wires running from the t-stat to the air handler. We do not see this often,but now and then it happens.If that is the problem you can substitute any wire extra in the harness to repair the short.ADDITIONAL INFO.Pulling the green wire and it still runs almost certainly means a short or perhaps when installing the new board something  may have got connected to the wrong terminal .If you are handy with a multi meter you can test the wires from the t-stat to the air handler to find a short. You can also trace back from the from the fan to see exactly where the current is coming from this is getting into HVAC tech work unless you can test for shorts and read a wiring diagram.Hope we have helped.