dold (AT) 2003XAccor (DOT) usenet.us.com writes:

This is for the 92 Civic; I don't know if it applies to other years in
the Civic line, but I have seen this arrangement in other cars too:

The fresh/recirc button simply controls an air door at the inlet of the
heater, and nothing else.

The cycling of the A/C compressor is controlled (under normal
conditions) by a thermostat embedded in the evaporator, and nothing
else. This tries to keep the evaporator at 2-5 degrees C, cold enough
for maximum cooling without ice forming. The only time the compressor
will run continuously instead of cycling is when the system cannot keep
the evaporator cool enough.

In the civic, compressor clutch cycling is what controls the capacity of
the A/C system. I suppose you could also build a system where the
clutch is always engaged, and the TEV valve controlled system capacity
and prevented freezing. But that would waste fuel.

Dave

The cycling controls to keep the A/C condenser at the proper
temperature are independent of the recirculating control. The A/C may
stay on more if you draw in outside, warmer air, but because it is
warmer, not because the A/C operates differently.

As to someone else's point about fuel consumption to cool outside
versus inside air, I'd be surprised if you could even measure the
difference. And remember, depending on how many people you have, they
generate a lot of humidity just breathing. That's why car windows
steam up a lot more with recirculating. Most manuals suggest
recirculating as a way to more quickly cool or heat at car at the
start, but that once cooled down or warmed, you should switch to fresh
air.


On Thu, 10 Jul 2003 18:58:15 +0000 (UTC),
dold (AT) 2003XAccor (DOT) usenet.us.com wrote: