Coleman Mach 3 coils freezing
We tried to run our A/C for the first time this year and it would try to cool for about an hour, then the evaporator coils would be iced over and it would not cool any more. The unit is a Coleman Mach...
Forum Discussion
TenOC wrote:
...coil freezing is caused by low Freon... On my home A/C there is a thermostat located at the coils...
Low refrigerant as a cause, is true. What happens, it there is no longer sufficient refrigerant to maintain adequate pressure in the Evaporator. What happens is, the refrigerant expands "prematurely" right where it enters the Evap. If that produces a sub-freezing temperature, frost begins there.
Another cause is a Fouled Evaporator. Dust and Dirt reduce air flow and also insulate the coils under that layer of "stuff." Once one area freezes, that block of frost/ice expands till a big part of the evap is clogged with frost.
Tied into all this, of course, anything else that reduces air flow (like Fan on Low not High)promotes freezing. An otherwise OK A/C can freeze on a humid day with Low Fan.
And, so can bringing extremely humid air into the evap area in the form of an intake air leak to the outside.
RV A/C units don't have the Freeze Sensor unless they are Ducted. The Ductless, with Fan and Temp Knobs, like mine and apparently like the one in this thread, don't have that feature.
