RE: climate control hacking

[Bill Samaras DTN 223-7322 27-May-1993 0837 <samaras@wrksys.enet.dec.com>]

I have some answers...

>recirculate:
>
>i have not been able to get the system to recirculate with a/c on.
>this is nice to have if the car in front of you is belching oil or
>diesel fumes.  setting "LO" temperature is supposed to do it, but
>according to the display it doesn't.  only recourse is "OFF"

You can force recirculation 2 ways. Either:

        1. Turn the system OFF
        2. Set the control to AUTO and the temp to LO. (This won't work in
           BI-LEV). Be sure not to use the LO or HI fan buttons, as these
           disengage recirculation.

During normal operation, recirculation only occurs in AUTO mode when the
interior temperature is far above outside temperature.


>a/c:
>
>i have not tried the a/c in cold weather, but in temperatures over
>70F, the compressor and the electric fan runs continuously.
>temperature regulation is achieved by (gasp!!) opening the heater
>valve.  no doubt the intent of this is to lower the interior humidity,
>but being mechanically sympathetic i would have preferred the
>compressor and fan to shut off periodically... ugh!!

There is a temperature sensor that will not allow the compressor or fan to run
when the outside temp is below ~40F.  You are correct that warm air is blended
in with the cool air to get the correct temperature, but the compressor can
still cycle on and off.  You may not see any cycling at idle, but it should
occur during normal driving.  The graphic display on channel 7 will show that
the compressor is always on, but that is not the case. THe graphic display
shows that the compressor is enabled. Cycling is controlled by a separate
control system that includes a thermostat in the evaporator (to prevent
freezeup). The only way to know if the compressor cycles is to watch the
clutch.  These cars have a "muffler" on the high pressure side of the
compressor circuit to absorb the shock when the compressor turns on.  It is
hardly noticable that the compressor cycles.  If you determine that the
compressor indeed never cycles, I'd suspect you are low on freon.

good luck,
...bill