“ MY QUESTION IS, IF THE TWO SYSTEMS ARE MISMATCHED. WHAT NEEDS TO BE REPLACED? IS SOMETHING ELSE CAUSING THESE ERRORS. ? “
https://www.theacoutlet.com/document...man-GSZC18.pdf
Page 19 shows all the matches, both systems are not matched, but will that cause your issues...??? Don’t know..
https://ahridirectory.org/Home/Downl...9myah1/DOzjaBf
https://ahridirectory.org/Home/Downl...9AvG8pxetvrVpn
Both upstairs and downstairs says you need the 37C model Air Handler which stands for 21” wide your upstairs has the 37B 17” wide Air Handler.
The other 36C number shows you need a 37C model.
To bad they never installed AHRI matches as those two system would easily qualify for any rebates your state or local utility company may have, but you need a matching AHRI system.
BTW it’s GSZC18 not GSCZ18
Did someone at least register those systems? If not the manufacturers warranty decreases significantly if never registered ( California and Quebec need not to be registered to receive the full manufacturers warranty)
“ SHALL I HAVE THE DEALER REMOVE THE EQUIPMENT AND START ALL OVER. “
Ask them why they did not install AHRI matched system, if they say we did, then ask them to prove it by providing the AHRI certificates number like the two given..