On Thu, 25 Feb 2016 08:42:15 -0000 (UTC), gregz
wrote:

Ed Pawlowski wrote:
On 2/24/2016 7:13 PM, Ashton Crusher wrote:
Question - If the AC in the car is making you too cold and you turn
the temp dial to "warmer" to make the air coming out less cold will
that make the AC work harder and make your gas mileage worse? Why?



NO. it just moves a door to mix in some warmer air. Aside from that, the
AC in cars today is very efficient and makes little difference to the
mpg. Comfort is more important that a tiny difference in fuel cost.

All my smaller cars show acceleration decrease with compressor on.

An older car of mine, the temp slider controlled the thermostat off the
evaporator. Never liked door mover systems. I'm going to assume, climate
control also uses the thermostat method. The moving door technique should
limit the air going through evaporator, thus limiting compressor usage.

Greg
There are virtually no "throttled" systems any more - and have not
been for decades. The compressor turns off and on th controll
pressures - and therefore heat transfer. Virtually all climate control
systems use "air blend" technology
Some systems used fixed orifice, some use an automatic orifice, and
some use a temperature controlled expansion valve TXV) which senses
the temperature of the evaporator and controls the amount of
refrigerant allowed int the evaporator to prevent icing etc. There is
also something called an "expansion block"system

The AC system controls the pressures and temperatures of the
refrigerant for most efficient operation - the blens doors control the
temperature of the air inside the vehicle. Newer compressor and
control technology improve the efficiency.