GMC 1986 P-Truck Service Manual page 66

Dash Mounted System-Motor Home C h a s s is ................................................................................................... 1B-64
Condensor R e p lacem ent...................................................................................................................................... 1B-64
Receiver-Dehydrator R eplacem ent...................................................................................................................1B-65
Sight Glass Replacement...................................................................................................................................... 1B-65
Blower-Evaporator Assembly R e p la c e m e n t................................................................................................. 1B-66
Blower Assembly Replacement........................................................................................................................... 1B-66
Expansion Valve, Evaporator and/or Evaporator Case R eplacem ent........................................................ 1B-67
Thermostatic and/or Blower Switches Replacem ent...................................................................................... 1B-67
Blower Motor Resistor R e p la ce m e n t................................................................................................................ 1B-67
Fuse R e p lace m e n t.................................................................................................................................................1B-67
S pecifica tio ns..............................................................................................................................................................1B-68
CCOT A/C SYSTEM
The CCOT (Cycling Clutch Orifice Tube) A/C system
performs heating and cooling. Air enters the vehicle
and passes through the cooling unit (evaporator) and
through (or around) the heating unit. The system is
called a " reheat" system. The evaporator cools the air
passing through the core when the air conditioning
system is in the cooling mode.
On C-K and G series, a pressure sensing switch,
located near the top of the accumulator, controls
com pressor operation. The switch responds to
pressure changes to turn the compressor ON or OFF.
System operation:
Outside air or recirculated air enters the system and
is forced through the system by the blower. As the air
passes through the evaporator core, it receives
maximum cooling if the air conditioning controls are
positioned for cooling.
From the evaporator, the air enters the heater and air
conditioner selector duct assembly where, by means of
diverter doors, it passes through or bypasses the
heater core in proportions necessary to provide the
desired outlet temperature. The air enters the vehicle
through either the floor distributor duct or the dash
outlets.
During cooling, the air is cooled by the evaporator to
below comfort level then warmed by the heater to the
desired temperature. During " heating only" the evapo­
rator does not operate, and ambient air is warmed to
the desired level in the same manner.
REAR INTERIOR ROOF
MOUNTED SYSTEMS
(SUBURBAN & G SERIES)
These systems operate with the front system - they
do not operate independently. However, control of the
rear blower motor speed is possible when the front
CONTENTS (CONTINUED)
DESCRIPTION
1. Power Element Thermobulb 8. Spring Seat
2. Cover
3. Diaphragm Back-up Plate
4. Body
5. Screen
6. Orifice
7. Carriage Spring
system at OFF. Rear air circulation without the refriger­
ant function is possible by operating the rear blower
control switch.
These self-contained units operate on inside
(recirculated) air. Air enters the unit and passes
through the evaporator core into the passenger
compartment through the air distributor duct. The front
system controls the rear system. A three-speed blower
switch controls the rear interior roof mounted system.
AIR CONDITIONING 1B-3
Figure 1-Thermostatic Expansion Valve
9. Carriage Seat
10. Seat
11. Actuating Pin
12. Diaphragm
A. Inlet
B. Outlet
F-00190