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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
BODIES AND CABS
AIR CONDITIONING
To properly air condition your cab in warm weather
close both the driver and passenger floor heat dumps and
open the instrument panel outlets. Close all windows and
ensure the vent knob is turned to its full clockwise position
(vent door closed). Set the "HTR" lever on the "OFF" position
and "A/C" lever on "COLD". For maximum cooling move the
"FAN" switch to the "HI" position. (The fan must be on for A/C
operation.) Place the "AIR OUTLETS" lever on the "CAB"
position, then adjust the instrument panel outlets to evenly
distribute the air around the occupants' head, chest and belt
areas. If foot areas feel warm, partially open heat dumps to
achieve desired comfort level.
Initial Cooling - Always park in the shade when
possible. But if your vehicle has been parked in open sun with
the windows up, remove overheated air inside by driving with
the windows down for one or two city blocks. You can turn on
the air conditioner controls at the time you start the vehicle
engine. After a short distance with the windows down, roll
them up again -- all the way -- adjust air flow and temperature
to your liking.
Stale Air and Smoke - To remove stale air or smoke
while air conditioner is operating, you may want to open a
window vent slightly for a short period of time.
Small amounts of water draining out of air
conditioner's drain tube is normal. This is condensed
moisture which has been removed from the air inside your
vehicle.
The air conditioning system incorporates a low
pressure switch which throws a relay to disengage the
compressor clutch if evaporator outlet pressure falls below a
certain level. To restart the air conditioning after an automatic
shut-down has occurred, the operator must do one of the
following:
1.
Place "A/C" lever in "OFF" position and then back
"ON",
OR
2.
Place blower switch in "OFF" position and then back
"ON".
If system continues to shut down automatically, it will
be necessary to diagnose the system for the cause of low
pressure.
Fig. 22 Air Conditioning Controls Set for Maximum Cooling
DEHUMIDIFICATION
The
heater-defroster
systems
can
be
operated
simultaneously with the air conditioner during mild weather
and high humidity conditions for dehumidification of the moist
air. To obtain maximum dehumidification, set the "A/C" lever
to "COLD", place the fan switch on "HI" and move the "HTR"
lever towards "HOT" until a comfortable temperature is
maintained. The air conditioner will remove the humidity
while the heater keeps the cab comfortable.
Fig. 23 Controls Set for Dehumidification of Cab
PERIODIC MAINTENANCE
To assure optimum operating efficiency, heating and
air conditioning systems must be properly maintained. (See
MAINTENANCE OPERATIONS.)
CTS-2731 Page 14
PRINTED IN UNITED STATES OF AMERICA
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