Re: 1955-56 Factory Air Conditioning

Posted by HH56 On 2019/3/21 18:06:16

This thermostat is just the typical on/off switch that controls the compressor clutch as used in a basic hang on unit -- and what most factory systems went to after the gas crisis in order to improve efficiency numbers. When the evaporator reaches the set temp or gets to the point there might be water freezing on the fins it turns the compressor off and when the evaporator warms up again it turns it back on. It has an advertised evaporator adjustment range of about 33-60 degrees.

The 55-6 Packard system had the compressor running all the time AC was turned on. The modulator valve controlled the temp and was fixed at around 40 degrees. When that temp was reached it opened to allow most of the refrigerant to bypass the evaporator and short circuit back to the compressor to essentially starve the evaporator and slow the cooling. As the evaporator warmed up the valve closed and forced the refrigerant to flow thru the evaporator again.

There are advantages and disadvantages to both methods but at the moment my vote for disadvantage prize goes to the Packard system because modulator valves that will fit seem to be all but extinct and mine is kaput.