WD Catalog 2018

828 / 1003

Chapter 2 – System Operation
2-2 - -
HEATER–FLOOR OR
BULKHEAD MOUNTING
NOTE LETTERS IN
CIRCLES SHOW THE
MOUNTING
LOCATION FOR THE
SYSTEMS
ILLUSTRATED A
THROUGH G A
E
C B
D
F
G
C
A
B
C
D
E
F
G REMOTE MOUNTED
CONDENSER WITH
RECEIVER-DRIER AND
DUAL FANS & MOTORS
ROOF MOUNTED AIR
CONDITIONER WITH
OVERHEAD AIR
DIFFUSERS AND
CONTROLS
UNIVERSAL AUXILIARY
HEATER (DEFROSTER OPTIONAL)
ADD ON AC FOR IN-
CAB MOUNTING TO
BACKWALL
AC/HEATER IN DASH MOUNT COMBO
SYSTEM WITH SLEEPER UNIT
CUSTOM DESIGN AC/
HEATER COMBO UNIT
INTEGRATES WITH EXISTING
DASH COMPONENTS.
NOTE POSITION OF VENT
(X) TO DEFROST
WINDSHIELD AND UP
FRONT SYSTEM CONTROLS
(X)
By law, all trucks have a heater/defroster as part of the standard equipment.
When there is a reason to add air conditioning, there are options to meet
different needs. The available space in the cab, operating environment, and
owner preference can all play a part in the type of AC unit selected. You will
probably encounter roof-mounted and in-cab add on systems, and even systems
where the condenser is mounted on the roof and the evaporator is attached to
the back panel or mounted under the dash. In cooler climates you may come
across a cab with two heaters, the original and an auxiliary unit.
Air Conditioner—System Operation
We have described the movement of heat energy and basic HVAC system
function in Chapter 1. Now we will go into some detail on how an air condi-
tioner operates. The system is sealed to keep out air and moisture. To operate
properly, the inside of the system contains a measured amount of refrigerant
and special refrigerant oil that keeps the system lubricated. Figure 2-2 is an
illustration of system components without the cab outline, in-cab controls,
component housing, and air ducts or vents. Please study it for a moment. Note
the information printed next to each component. Remember that the compo-
nents may be positioned and attached to the truck in various locations.
Figure 2-1
These illustrations show a
basic heater, HVAC system,
the combo system with
sleeper unit, add on AC roof
top and in cab units, roof
mounted condenser and
auxiliary units.