Dodge RAM TRUCK 1500 1995 Service Manual page 1682

HEATING AND AIR CONDITIONING 24 -13
Fig. 2 Vacuum Circuit Test
VACUUM CIRCUITS
GREEN
B L A C K G R E E N
R E C I R C U L A T I N G F L O O R / D E F R O S T
J 9 4 2 4 - 2 7
BLOWER MOTOR TEST
Use volt/ohmmeter for tests and Refer to the Group
8W Wiring Diagrams for complete wiring schematic.
Possible causes for no blower:
• Open feed circuit: Test feed circuit from fuse to
blower motor.
• Open ground circuit: Test ground circuit to Heater
A/C switch, Blower resistor and Blower motor.
Fig* 8 Blower Motor Resistor
• Open one or more blower resistors: Test all blower
resistors.
• Faulty blower switch: Test blower switch.
• Faulty blower motor: Test blower motor.
BLOWER MOTOR VIBRATION -
(1) Possible location or cause of blower motor vi­
bration are as follows:
• Blower motor assembly loose in heater A/C hous­
ing.
• Blower wheel loose on motor shaft.
• Blower wheel out of balance or bent.
• Blower motor defective.
(2) Possible location or cause of blower motor noise
are as follows: (To verify blower noise disconnect
blower motor wire lead connector and operate heater
or A/C system. If noise goes away, proceed with pro­
cedure.)
• Foreign material in heater A/C housing around
blower wheel
• Blower wheel rubbing heater A/C housing
® Blower motor defective
AIR CONDITIONING CYCLING SWITCH16
The switch is mounted on top of the accumulator.
The switch is wired in series with compressor clutch.
The switch contacts are normally open when the suc­
tion pressure is approximately 172 kPa (25 psi) or
lower. The switch will close when suction pressure
rises to approximately 296 kPa (43 psi) or above.
Lower ambient temperatures, below approximately
-1°C (30°F) during cold weather will also open the
switch contacts. This is due to the pressure/tempera­
ture relationship of the refrigerant in the system.