| Just went through trying to figure out what all the pins and jumpers are on my Yorkguard IV so maybe I can help. So far I've not need the upgrade to VI (fingers crossed).
From my notes, the LTCO is just there to lock out the HP below that temp and always bring on aux heat, so I don't see it affecting defrost at all. 15 sounds good. Mines set to 10 and the tstat is set to 15 (I like having control from the house).
From my notes, at least on the IV, defrost is an algorithms built into the board looking at liquid line temp, ambient air temp with time factors. So this begs the question are temp sensors working and wired in correctly? Also have you ever seen the unit go into defrost on its own, as I'm not sure if a forced defrost from test pins exercises everything.
Finally York is pretty helpful so try calling them and see if they can put you in touch with some support. |