Refrigerologist
10-03-2008, 01:14 AM
Did any engineers' come across Swedish Royales attempt to carry out defrosting of island site freezers by reversing the direction of the evaporator fan motors and running them at a higher speed! These were dual voltage reversible shaded pole motors, so the cabinets were fitted with 240 v to 110 v step down transformers. I remember a shop called Adsega Foods in Dagenham, it was bought by Tesco and had a prototype installed. The service call I had was cabinet temperature high during the day. I checked everything, superheat, subcooling, charge nothing found. Then it went into defrost, and I noticed the old paragon defrost time clock fitted with pressure termination was set for 120minutes defrost!! And the pressure termination setting was set to its' highest setting I think from memory it was about 120lbs/in2 (R502). Being a naive 20 year old I reduced the times to 28minutes failsafe (a Marks and Spencer standard). I didn't reduce the pressure termination as I thought with no heaters it would need 28minutes!! Lo and behold it was iced up in less than 36 hours. The previous service company had provided 2 long defrosts in the night!! And two shorter ones in the day. The time clock had gone out of sync and so the food was defrosting in the day instead of overnight!! Needless to say we installed electric defrost!