"Vic Dura" wrote in message
...
On Wed, 29 Jun 2005 12:49:15 GMT, in alt.home.repair
evaporator ice formation "Travis Jordan" wrote:

Vic Dura wrote:
I'm just curious as to what the theory behind that is.

When the refrigerant charge is low the evaporator coil gets starved for
refrigerant and this results in reduced pressure at the inlet piston or
expansion valve, thus allowing the refrigerant to vaporize at a lower
temperature - below 32 degrees. At this point the first part of the
coil will freeze.

Ok, that makes perfect sense to me. Thanks for the clear explanation.


I think another way to look at it is when the compressed freon enters the
condenser it is a hot gas. If there is the correct amount of freon, just
the right amount of heat will be removed such that it will change to a
liquid but still be quite hot. The hot liquid expanded through the
evaporator gets the correct amount of cooling.

If the freon is low there may be only a small amount of liquid exiting the
condenser and it will be cooler than normal. When it expands in the
evaporator it can produce temperatures below freezing.