Fan speed controllers

[Tycho]

Thanks tycho

I’ll have a play around next time I’m on site with it. just feel it was condensing to low hence not feeding to the TEV correctly and I was having issues with the coil freezing but only on the bottom half.
if I fit a pressure controll switch or speed controller I can control the head pressure a little better and hopefully solve the problem.
thanks again.

Is the evaporator superheat set by a electronic valve or a thermostatic expansion valve?

Just asking, because any subcooling you have on the high side is a bonus once it gets to the expansion valve.

If the bottom half of the evaporator is icing over, I am more inclined to think it has something to do with the defrost timer or placement of a deforst sensor.

if it's a pump down system, with electrical defrost, it could be that the defrost temperature sensor is placed at a bad location so it gets warm too fast, and/or the defrost timer is set to short and stops the defrost before the coil is fully defrosted.

Or

in one absurd case I had, that the solenoid feeding the evaporator has a slight leak, so the compressor kept running during the defrost cycle.

and another case, the evaporator was directly above the door to the room, so every time they went in or out, the warm humid air from outside went straight up into the evaporator and turned it into an icecube

Had I been you, I would have first checked the placement of the evaporator, that it is not above or close to any doors, second, observed the evaporator during a full defrost cycle to make sure it was fully defrosted, and that it wasn't just partially de-iced, made sure that the compressor properly pumped down when a defrost cycle started (it might start or stop a few times) but it should'nt start and stop continously during defrost.

I'm assuming this because you say you were having issues with the bottom half of the coil freezing, I understood this as the bottom half of the coil is icing over <--- if this is the case, then check the defrost

if by bottom half freezing, you mean only the bottom half of the coil is getting cold, then check the superheat across the evaporator, because either it is to high, or there is not enough liquid in the system. most optyma Units have a liquid sight glass, but it's placed close to the condensing unit so if the evaporator is some ways away, you can't tell if you have clean liquid all the way to the TEV)

your last post provided the last piece of the puzzle, and I can tell you that the problem is not the subcooling of the liquid from the condenser, it's either the defrost timer, defrost sensor placement (icing over), leaking solenoid, TEV setting or not enough refrigerant (only icing on lower half and icing over). pretty sure this has nothing to do with the subcooling of the liquid leaving the condenser.

I'm guessing the system only has a sight glass on the liquid leaving the condensing unit (if at all), so you don't really know if there is pure liquid coming to the TEV.

I'd have started by checking the defrost amd that it was properly deiced before a new freezing cycle started, boring and time consuming, I know, but it has to be done

[Airconking]

Is the evaporator superheat set by a electronic valve or a thermostatic expansion valve?

Just asking, because any subcooling you have on the high side is a bonus once it gets to the expansion valve.

If the bottom half of the evaporator is icing over, I am more inclined to think it has something to do with the defrost timer or placement of a deforst sensor.

if it's a pump down system, with electrical defrost, it could be that the defrost temperature sensor is placed at a bad location so it gets warm too fast, and/or the defrost timer is set to short and stops the defrost before the coil is fully defrosted.

Or

in one absurd case I had, that the solenoid feeding the evaporator has a slight leak, so the compressor kept running during the defrost cycle.

and another case, the evaporator was directly above the door to the room, so every time they went in or out, the warm humid air from outside went straight up into the evaporator and turned it into an icecube

Had I been you, I would have first checked the placement of the evaporator, that it is not above or close to any doors, second, observed the evaporator during a full defrost cycle to make sure it was fully defrosted, and that it wasn't just partially de-iced, made sure that the compressor properly pumped down when a defrost cycle started (it might start or stop a few times) but it should'nt start and stop continously during defrost.

I'm assuming this because you say you were having issues with the bottom half of the coil freezing, I understood this as the bottom half of the coil is icing over <--- if this is the case, then check the defrost

if by bottom half freezing, you mean only the bottom half of the coil is getting cold, then check the superheat across the evaporator, because either it is to high, or there is not enough liquid in the system. most optyma Units have a liquid sight glass, but it's placed close to the condensing unit so if the evaporator is some ways away, you can't tell if you have clean liquid all the way to the TEV)

your last post provided the last piece of the puzzle, and I can tell you that the problem is not the subcooling of the liquid from the condenser, it's either the defrost timer, defrost sensor placement (icing over), leaking solenoid, TEV setting or not enough refrigerant (only icing on lower half and icing over). pretty sure this has nothing to do with the subcooling of the liquid leaving the condenser.

I'm guessing the system only has a sight glass on the liquid leaving the condensing unit (if at all), so you don't really know if there is pure liquid coming to the TEV.

I'd have started by checking the defrost amd that it was properly deiced before a new freezing cycle started, boring and time consuming, I know, but it has to be done

signt glass located at the condenser and it’s running with a TEV.... defrost probe located in a good position at the top end of the coil away from the heaters.
Evaporators located at the back of the freezer away from the door.
Ill Check afew things suggested next time I visit and hopefully get to the bottom of the problem