have a really old federal deli case. r12 with k body semi hermetic. it does have 2 evap fans, coil runs along the length of the front bottom, fans on back side bottom of case. 1/2 hp k body, 1/2 ton txv, about 6-8 foot case no model # left. evap coil froze solid, seriously froze. unit has no defrost clock, an air sensing t-stat, running on 414b. superheat a little high at 17 degrees. head 190, low 24 at 45 box temp. (ran out of time after dethawing and running, they were closing) does pull down but seems pretty slow to do so.
my plan- add a 9000 series defrost clock, give it a couple good 1 hour defrosts overnight, also add a white roders 16901 and make it coil sensing at 41 cut in, 23 cut out. does this sound good? this is a really good customer that needs to keep this going a little longer. BTW i had about 6 degrees subcool, no reciever, at the 45 degree box.
my other thought is to go to 416a along with clock and stat to try and help high head in hot ambient. really appreciate any help. thanks