DAEWOO M-150 BL2
SECTION 7B
MANUAL CONTROL HEATING, VENTILATION,
AND AIR CONDITIONING SYSTEM
CAUTION: Disconnect the negative battery cable before removing or installing any electrical unit or when a
tool or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable
will help prevent personal injury and damage to the vehicle. The ignition must also be in B unless otherwise
noted.
TABLE OF CONTENTS
Description and Operation 7B-2. . . . . . . . . . . . . . . . . .
System Components – Functional 7B-2. . . . . . . . . . .
Component Locator 7B-3. . . . . . . . . . . . . . . . . . . . . . . .
A/C System 7B-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Information and Procedures 7B-5. . . . .
General Diagnosis 7B-5. . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing the Refrigerant System 7B-5. . . . . . . . . . . . . .
Insufficient Cooling “Quick Check”
Procedure 7B-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure-Temperature Relationship
of R-134a 7B-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing the Refrigerant System 7B-7. . . . . . . . .
Air Conditioning System Diagnosis 7B-8. . . . . . . . . . . . .
Insufficient Cooling Diagnosis 7B-8. . . . . . . . . . . . . . .
Symptom Diagnosis 7B-11. . . . . . . . . . . . . . . . . . . . . . . .
Pressure Test Chart (R-134a System) 7B-11. . . . . . .
Repair Instructions 7B-13. . . . . . . . . . . . . . . . . . . . . . . .
On-Vehicle Service 7B-13. . . . . . . . . . . . . . . . . . . . . . . . .
General A/C System Service Procedures 7B-13. . . . . .
O-Ring Replacement 7B-13. . . . . . . . . . . . . . . . . . . . .
Handling Refrigerant 7B-13. . . . . . . . . . . . . . . . . . . . . .
Handling of Refrigerant Lines and Fittings 7B-13. . .
Maintaining Chemical Stability in the
Refrigeration System 7B-14. . . . . . . . . . . . . . . . . . .
Discharging, Adding Oil, Evacuating, and
Charging Procedures for A/C System 7B-14. . . . . Serviceable Components 7B-17. . . . . . . . . . . . . . . . . . . .
Control Assembly and Control Cables 7B-17. . . . . . .
Blower Motor and Cooling Hose 7B-17. . . . . . . . . . . .
Blower Resistor 7B-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Motor Switch 7B-17. . . . . . . . . . . . . . . . . . . . . .
A/C Push Knob 7B-18. . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver–Dryer and Dual Cut Switch 7B-18. . . . . . . .
Receiver–Dryer Bracket 7B-20. . . . . . . . . . . . . . . . . . .
Compressor 7B-20. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Condenser 7B-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A/C High Pressure Pipe Line 7B-22. . . . . . . . . . . . . . .
A/C Low Pressure Pipe Line 7B-25. . . . . . . . . . . . . . .
Evaporator Unit and Drain Hose 7B-26. . . . . . . . . . . .
Unit Repair 7B-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Evaporator Core and Expansion Valve 7B-28. . . . . .
Compressor Overhaul 7B-29. . . . . . . . . . . . . . . . . . . . .
Specifications 7B-30. . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Specifications 7B-30. . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 7B-30. . . . . . . . . .
Special Tools and Equipment 7B-31. . . . . . . . . . . . . .
Special Tools Table 7B-31. . . . . . . . . . . . . . . . . . . . . . .
Schematic and Routing Diagrams 7B-32. . . . . . . . . .
A/C Diagrams 7B-32. . . . . . . . . . . . . . . . . . . . . . . . . . . .
A/C Airflow (Typical) 7B-33. . . . . . . . . . . . . . . . . . . . . .
A/C System (Typical) 7B-33. . . . . . . . . . . . . . . . . . . . .
7B–2 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
SYSTEM COMPONENTS
–FUNCTIONAL
Compressor
All compressors are belt–driven from the engine crank-
shaft through the compressor clutch pulley. The com-
pressor pulley rotates without driving the compressor
shaft until on electromagnetic clutch coils energized.
When voltage is applied to energize the clutch coil, the
clutch plate and hub assembly are drawn toward the
pulley. The magnetic force locks the clutch plate and
pulley together as one unit to drive the compressor
shaft.
Condenser Core
The condenser assembly in front of the radiator consists
of coils which carry the refrigerant and cooling fins that
provide the rapid transfer of heat. The air passing
through the condenser cools the high–pressure refriger-
ant vapor and cause it to condense into a liquid.
Expansion Valve
The expansion valve is located on the passenger
compartment side of the dash panel. The expansion
valve can fail in three different positions: open, closed,
or restricted. An expansion valve that fails in the open
position will result in a noisy A/C compressor or no cool-
ing. The cause can be a broken spring, a broken ball, or
excessive moisture in the A/C system. If the spring or
the ball is found to be detective, replace the expansion
valve. If excessive moisture is found in the A/C system,
recycle the refrigerant. An expansion valve that fails in
the closed position will result in low suction pressure and
no cooling. This may be caused by a failed power done
or excessive moisture in the A/C system. If the power
dome on the expansion valve is found to be defective,
replace the expansion valve. If excessive moisture is
found in the A/C system, recycle the refrigerant.
A restricted expansion valve will result in low suction
pressure and no cooling. This may be caused by debrisin the refrigerant system. If debris is believed to be
cause, recycle the refrigerant, replace the expansion
valve, and replace the receiver/dryer.
Evaporator Core
The evaporator is device which cools and dehumidifies
the air before it enters the vehicle. High–pressure liquid
refrigerant flows through the expansion tube (orifice)
and becomes a low–pressure gas in the evaporator. The
heat in the air passing through the evaporator core is
transferred to the cooler surface of the core, which cools
the air. As the process of heat transfer from the air to the
evaporator core surface is taking place, any moisture
(humidity) in the air condenses on the outside surface of
the evaporator core and is drained off as water.
Receiver–Dryer
The sealed receiver–dryer assembly is connected to the
evaporator outlet pipe. It acts as a refrigerant storing
container, receiving liquid and some vapor and refriger-
ant oil from the evaporator.
At the bottom the receiver–dryer is the desiccant, which
acts as a drying agent for the moisture that may have
entered the system. The receiver–dryer is serviceable
only as an assembly.
Dual Cut Switch
The dual cut switch controls compressor operation when
the cycling refrigerant pressure is dropped or surged.
Evaporator Thermistor
A semiconductor which resistance is noticeably changed
as the change of temperature. When the refrigerant tem-
perature of the evaporator drops to 0C (32F) and be-
low, the evaporator cores get stuck with frost or ice,
reducing the airflow, lowering the cooling capacity. The
thermistor is a sensor which is used to prevent from frost-
ing or icing.
The thermistor is installed on the evaporator.