Peterbilt Model 320 Operator's Manual after 8-07 - Peterbilt Motors ...

PART 4: CONTROLS AND DISPLAYS
mounted in the cover piece of the unit located in the cab
ceiling. It contains a rotary switch to select blower speed
(see next illustration).
Heating And Air Conditioning Controls
To cool the cab, turn on the air conditioning system and
adjust the blower speed until comfortable. The amount of
cooling is controlled by
• the temperature of the evaporator core
• the speed of the blower that forces air through the core
and into the cab
NOTE: When the air conditioner isn’t in regular use,
operate it for at least 15 minutes once a month. This
will lubricate the seals in the system
For More Efficient Heating and Cooling...
JPR033
• For immediate heating of a cold cab, operate the heating
system with the “Fresh/Recirc” switch in the “Recirc”
position. Switch to the “Fresh” position when the
cab has reached a comfortable temperature.
• For immediate cooling of a hot cab, initially open a
cab window. For maximum summertime cooling, both
heater control valves on the engine should be shut (if
so equipped).
• For both heating & cooling, use lower blower speeds
and intermediate temperature selector positions to
modulate cab temperature.
R(08/07) Y53-6015 – 41 –