capillary tubes

[JimmyMurphy]

I never work on capillary tubes systems. I just want to clarify what the symptoms of an overcharge are, and symptoms of an undercharge?

[Brian_UK]

As a system goes undercharged you will begin to see frost/ice build up on the coil then that will fall back to the capillary itself.

[Actinide]

Capillary units are a critically charge system. You have to be pretty exact with the refrigerant charge. A correctly charge capillary unit will have no frosting on the capillary where it enters the evaporator, warm dryer, and your head pressure will be at spec. Under charged symptoms are low back pressure, frosting on capillary, cool dryer, low discharge temperature/pressure, low efficiency in cooling. A over charged system will have a high discharge temperature/pressure, hot dryer, higher suction pressure, usually on capillary system they have a suction line accumulator for when the unit is on off cycle the high-low sides equalize through the capillary to stop flooding to compressor when starting up, if you have frosting on accumulator whilst running can also indicate that unit is slightly over-charged.

Hope this helped :)