I am new to the forum this is my first post. I read most of the stickied and will try to follow the guidelines as much as possible.
Quick Background. I started work really with my dad when I was fourteen, he just retired so I took over the business, I'm 27 now. This is my first big refrigeration call Robert has helped some too (with this call especially) but he is admittedly stumped too.
To the call:
The cooler is mainly a drink cooler with some dairy and meat products it has about 8 glass doors on the front, and the seals aren't that great in my opinon.
The unit it self is a walk in cooler with two evaporator coils about a 40ft service line run and a Copeland compressor (R22) outside to a shack really with less than adequate ventilation. Last year in March I helped my father change out the compressor (he retired in April). Quick about things about the condenser no Manufacturing plate what so ever so unsure of manufacturing date or system specs i.e. Factory charge. We charge it with 9.5 pds. taking in the accumulator and long service line. Both of the service ports were run downs and leaked when opend so we put a piercing valve on the low pressure line. The running pressure was 32 on the low with a sat temp of 8. And the sat temp on the high was 60 (checked with the digimon Manifold, su[perheat peripheral). The temps out of the evaporator coils range 25-21. Thermostat set to 31-28.
I get the call two weeks ago that the evaporator is frozen, so I went to check it out and one of the condensing fan motors was out so I replaced it and frosted the coil.
Got the call last week that it was freezing again so I figured fre-on. I checked the pressure on the low and it was 8psi. I defrosted the coils and it came up to about ten. I charged the unit with 8 pds of R22 and got the low pressure to hang around 29 with a sat temp of 8 and the high sat temp is 60.
So i have been checking this thing every day, its in my town. And the evaporator (one farthest from door is still frosting) and the expansion valve on the other side is starting to frost.
So did a more through check. The deforst timer out on had three pins set to 2 6 hour runs and one 12 hour. I add one more pin so now it has 4 30 min defrosts set at six hours each. Checked the thermostat, It doesn't kick out the condenser at all, but the power does cut when the temperature is bumped.
So here is the crazy thing it has a defrost timer set inside the cooler it self set to two defrost times midnite and noon. I believe this timer runs up two a solenoid in the liquid line. Have no clue what this is for.
I hope that was enough information, like I said my main focus is residential, any help or suggestions much appreciated. Please let me know if more info is need or if I am just nuts.