Trane EX 800 Defrost Problem

Mark58

I just bought an older home and first on the air unit inside I had to find the condensation leak, dry out the system,  replace the drywall,  have a local guy come in and clean and sanitize. I am thinking of adding a UV system.



The problem I  want to fix before winter is the TRANE EX 800 outside (from what I am told) does not defrost,  it starts the cycle,  you can hear the clicking, but it cycles non-stop while the fan goes off/on with the clicking (does that make sense).   I open the unit,  there was all kinds of growth from the sides, cleaned it out.  seems to heat well, and no visible damage.   What I don't know is where to look for the error,  is it most likley the control card or ???   I noticed that one wire was disconnected and covered in tape.