On 1/20/2013 11:56 AM, Ernie wrote:
The Daring Dufas wrote:

The most inexpensive residential AC systems lack a factory
installed head pressure control which is why it's not prudent
to run them in cold weather.

Why couldn't a thermostat that can sense condenser coil temperature
be used to turn on the fan when the coils reach some pre-determined
temperature?

That's exactly what the fan speed modulators do in the links I
provided. The ICM manufactured controls I use, come with a
temperature sensor that's attached to the high pressure line
on the condenser coil to operate the control.

You kept mentioning "head pressure control" which I interpreted as some
sort of pressure-sensor (sensing line pressure) as a way to operate the
fan.


Some methods use a simple pressure switch to turn the fan on/off. Some
use a pressure transducer which provides a variable signal to the
control and the others use a temperature sensor to provide a variable
signal to the fan speed control. ^_^

TDD