Chrysler Town & Country/Voyager, Dodge Caravan, Plymouth Voyager. Manual — part 131
HEATER AND A/C PERFORMANCE TESTS
VACUUM CIRCUITS—HEATER OR HEATER A/C CONTROL
.
HEATING AND AIR CONDITIONING
24 - 19
HEATER OUTPUT TEST
PRE-DIAGNOSTIC PREPARATIONS
Review Safety Precautions and Warnings in the
General Information section of this Group before per-
forming the following procedures.
Check the radiator coolant level, drive belt tension,
engine vacuum line connections, radiator air flow and
radiator fan operation. Start engine and allow to warm
up to normal running temperature.
WARNING: DO NOT REMOVE RADIATOR CAP WHEN
ENGINE IS HOT, PERSONAL INJURY CAN RESULT.
If vehicle has been run recently, wait 15 minutes
before removing cap. Place a rag over the cap and turn
it to the first safety stop. Allow pressure to escape
through the overflow tube. When the system stabilizes,
remove the cap completely.
MAXIMUM HEATER OUTPUT:TEST AND AC-
TION
Engine coolant is provided to the heater system by
two 16 mm (5/8 inch inside diameter) heater hoses.
With engine idling at normal running temperature, set
the control to maximum heat, floor, and high blower
setting. Using a test thermometer, check the air tem-
perature coming from the floor outlets, refer to Tem-
perature Reference chart.
If the floor outlet air temperature is insufficient,
refer to Group 7, Cooling Systems for normal engine
coolant temperature specifications. Both heater hoses
should be HOT to the touch (coolant return hose should
be slightly cooler than the supply hose). If coolant
return hose is much cooler than the supply hose, locate
and repair engine coolant flow obstruction in heater
system.
POSSIBLE LOCATIONS OR CAUSE OF OBSTRUCTED COOL-
ANT FLOW
(a) Pinched or kinked heater hoses.
(b) Improper heater hose routing.
(c) Plugged heater hoses or supply and return
ports at cooling system connections, refer to Group 7,
Cooling System.
(d) Plugged heater core.
(e) Water valve sticking or inoperative.
If proper engine coolant flow through heater system
is verified and floor outlet air temperature is still
insufficient, a mechanical problem can exist in the
heater system.
POSSIBLE LOCATION OR CAUSE OF INSUFFICIENT HEAT
(a) Obstructed cowl air intake.
(b) Obstructed heater system outlets.
(c) Blend-air door not functioning properly.
TEMPERATURE CONTROL
If temperature cannot be adjusted with the TEMP
lever on the control panel, or TEMP lever is difficult to
move, the following could require service:
(a) Blend-air door binding.
(b) Control cables miss-routed, pinched, kinked, or
disconnected.
(c) Improper engine coolant temperature.
A/C PERFORMANCE TEST
The air-conditioning system is designed to remove
heat and humidity from the air entering the passenger
compartment. The evaporator, located in the heater
A/C unit behind the instrument panel, is cooled to
temperatures near the freezing point. As warm damp
air passes over the fins in the evaporator, moisture in
the air condenses to water, dehumidifying the air.
Condensation on the evaporator fins reduces the
evaporators ability to absorb heat. During periods of
high heat and humidity, an air-conditioning system
will be less effective than during periods of high heat
and low humidity. With the instrument control set to
RECIRC, only air from the passenger compartment
passes through the evaporator. As the passenger com-
partment air dehumidifies, A/C performance levels
rise.
PERFORMANCE TEST PROCEDURE
Review Safety Precautions and Warnings in the
General Information section of this Group before pro-
ceeding with this procedure. Air temperature in test
room and on vehicle must be 70°F (21°C) minimum for
this test.
(1) Connect a tachometer and manifold gauge set.
(2) Set control to A/C, RECIRC, PANEL, or MAX
A/C, temperature lever on full cool and blower on high.
(3) Start engine and hold at 1000 rpm with A/C
clutch engaged.
(4) Engine should be warmed up with doors and
windows closed.
TEMPERATURE REFERENCE CHART
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HEATING AND AIR CONDITIONING
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(5) Insert a thermometer in the left center A/C outlet
and operate the engine for five minutes. The A/C clutch
may cycle depending on ambient conditions.
(6) With the A/C clutch engaged, compare the dis-
charge air temperature to the A/C Performance Tem-
peratures chart.
(7) If the discharge air temperature fails to meet the
specifications in the performance temperature chart.
Refer to the Diagnostic Analysis charts in this Group
for further test information.
A/C PERFORMANCE TEMPERATURES
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HEATING AND AIR CONDITIONING
24 - 21
REFRIGERANT SERVICE PROCEDURES
INDEX
page
page
Adding Partial Refrigerant Charge . . . . . . . . . . . . . 24
Charging Refrigerant System—Empty System
. . . . 26
Discharging Refrigerant System
. . . . . . . . . . . . . . 25
Evacuating Refrigerant System
. . . . . . . . . . . . . . . 25
Manifold Gauge Set Connections
. . . . . . . . . . . . . 23
Oil Level
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Refrigerant (R-12) Equipment
. . . . . . . . . . . . . . . . 22
Refrigerant Recycling
. . . . . . . . . . . . . . . . . . . . . . 23
Sight Glass Refrigerant Level Inspection
. . . . . . . . 22
Testing for Refrigerant Leaks
. . . . . . . . . . . . . . . . 24
SIGHT GLASS REFRIGERANT LEVEL INSPECTION
The filter-drier is equipped with a sight glass (Fig. 1)
that is used as a refrigerant level indicator only. This
sight glass is not to be used for A/C performance
testing. To check the refrigerant level, remove the
vehicle jack and clean the sight glass. Then start and
warm up engine, and hold idle at 1100 rpm. Place the
air-conditioning control on A/C, RECIRC and high
blower. The work area temperature should be at least
21°C (70°F). If a Fixed Displacement type compressor
does not engage, the refrigerant level is probably too
low for the Low Pressure Cut-Off switch to detect. Or,
with a Variable Displacement compressor, for the Dif-
ferential Pressure Cut-off to detect. If compressor
clutch does not engage, refer to Testing Refrigerant
System for Leaks in this Group. If compressor clutch
engages, allow approximately one minute for refriger-
ant to stabilize. View refrigerant through sight glass.
The suction line should be cold to the touch and the
sight glass should be clear.
If foam or bubbles are visible in sight glass, the
refrigerant level is probably low. Occasional foam or
bubbles are normal when the work area temperature is
above 43°C (110°F) or below 21°C (70°F). If suction line
is cold and occasional bubbles are visible in the sight
glass, block the condenser air flow. This will increase
the compressor discharge pressure (Do not allow en-
gine to over heat). Bubbles should dissipate. If not, the
refrigerant level is low.
WARNING: R-12 REFRIGERANT IS DETRIMENTAL TO
THE ENVIRONMENT WHEN RELEASED TO THE AT-
MOSPHERE. DO NOT RECHARGE AN A/C SYSTEM
BY ADDING R-12 REFRIGERANT TO A SYSTEM THAT
HAS A KNOWN LEAK.
The refrigerant system will not be low on R-12 unless
there is a leak. Find and repair the leak before charg-
ing.
R-12 REFRIGERANT EQUIPMENT
WARNING: EYE PROTECTION MUST BE USED WHEN
SERVICING AN AIR-CONDITIONING REFRIGERANT
SYSTEM.
TURN OFF (ROTATE CLOCKWISE) ALL VALVES ON
THE EQUIPMENT BEING USED BEFORE PROCEED-
ING WITH THIS OPERATION. PERSONNEL INJURY
CAN RESULT.
When servicing an air-conditioning system, it is
recommended that a suitable air-conditioning charging
station (Fig. 2) be used. An (R-12) refrigerant
recovery/recycling device (Fig. 3) should also be used.
This device should meet SAE standard J1991. Contact
an automotive service equipment supplier for refriger-
ant recycling/recovering equipment. Refer to the oper-
ating instructions provided with the equipment for
proper operation.
A manifold gauge set (Fig. 4) must also be used in
conjunction
with
the
charging
and/or
recovery/recycling device. The service hoses on the
gauge set should have manual (turn wheel) or auto-
matic back flow valves at the service port connector
ends. This will prevent refrigerant (R-12) from being
release into the atmosphere.
Fig. 1 Filter Drier and Sight Glass
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HEATING AND AIR CONDITIONING
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