Classic AutoAir 1971-1973 Mustang A/C system, Руководство по установке

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TEST CONDITIONS USED TO DETERMINE SYSTEM OPERATION
(THESE TEST CONDITIONS WILL SIMULATE THE AFFECT OF
DRIVING THE VEHICLE AND GIVE THE TECHNICIAN THE THREE
CRITICAL READINGS THAT THEY WILL NEED TO DIAGNOSE ANY
POTENTIAL PROBLEMS).
B. CONNECT GAUGES OR SERVICE EQUIPMENT TO HIGH/LOW
CHARGING PORTS.
C. PLACE BLOWER FAN SWITCH ON MEDIUM.
D. CLOSE ALL DOORS AND WINDOWS ON VEHICLE.
E. PLACE SHOP FAN IN FRONT OF CONDENSER.
F. RUN ENGINE IDLE UP TO 1500 RPM.
ACCEPTABLE OPERATING PRESSURE RANGES ( R134A TYPE)
1. HIGH-SIDE PRESSURES ( 160-250 PSI )
*Note- general rule of thumb is
two times the ambient (daytime) temperature, plus 15-20%.
2. LOW-SIDE PRESSURES ( 06-22 PSI in a steady state).
CHARGE AS FOLLOWS: R134A = 24 OZ.
NO ADDITIONAL OIL IS NECESSARY IN OUR NEW COMPRESSORS.
TYPICAL PROBLEMS ENCOUNTERED IN CHARGING SYSTEMS
NOISY COMPRESSOR.
A noisy compressor is generally caused by charging a compressor with
liquid or overcharging
A. If the system is overcharged both gauges will read abnormally high readings. This is
causing a feedback pressure on the compressor causing it to rattle or shake from the
increased cylinder head pressures. System must be evacuated and re-charged to exact
weight specifications.
B. Heater control valve installation - Installing the heater control valve in the incorrect hose.
Usually when this occurs the system will cool at idle then start to warm up when raising the
RPM’s of the motor. THE HEATER CONTROL IS A DIRECTIONAL VALVE; MAKE SURE THE
WATER FLOW IS WITH THE DIRECTION OF THE ARROW. As the engine heats up that water
transfers the heat to the coil, thus overpowering the a/c coil. A leaking or faulty valve will
have a more pronounced affect on the unit’s cooling ability. Installing the valve improperly
(such as having the flow reversed) will also allow water to flow through, thus inhibiting
cooling. Check for heat transfer by disconnecting hoses from the system completely. By
running down the road with the hoses looped backed through the motor, you eliminate the
possibility of heat transfer to the unit.
C. Evaporator freezing - Freezing can occur both externally and internally on an evaporator
core. External freeze up occurs when the coil cannot effectively displace the condensation
on the outside fins and the water forms ice (the evaporator core resembles a block of solid
ice), it restricts the flow of air that can pass through it, which gives the illusion of the air not
functioning. The common cause of external freezing is the setting of the thermostat and the
presence of high humidity in the passenger compartment. All door and window seals should
be checked in the event of constant freeze-up. A thermostat is provided with all units to
control the cycling of the compressor.
D. Internal freeze up
occurs when there is too much moisture inside the system. The
symptoms of internal freeze up often surface after extended highway driving. The volume of
air stays constant, but the temperature of the air gradually rises. When this freezing occurs
the low side pressure will drop, eventually going into a vacuum. At this point, the system
should be checked by a professional who will evacuate the system and the drier will have
to be changed.
E. Inadequate airflow to condenser - The condenser works best in front of the radiator with
a large supply of fresh air. Abnormally high pressures will result from improper airflow.
Check the airflow requirements by placing a large capacity fan in front of the condenser
and running cool water over the surface. If the pressures drop significantly, this will indicate
the need for better airflow.
F. Incorrect or inadequate condenser capacity - Incorrect condenser capacity will cause
abnormally high head pressures. A quick test that can be performed is to run cool water
over the condenser while the system is operating, if the pressures decrease significantly, it
is likely a airflow or capacity problem.
G. Expansion valve failure - An expansion valve failure is generally caused by dirt or debris
entering the system during assembly. If an expansion valve fails it will be indicated by
abnormal gauge readings. A valve that is blocked will be indicated by high side that is
unusually high, while the low side will be unusually low or may even go into a vacuum. A
valve that is stuck open will be indicated by both the high and low pressures rising to
unusually high readings, seeming to move toward equal readings on the gauges.
H. Restrictions in system - A restriction in the cooling system will cause abnormal readings
on the gauges. A high-side restriction ( between the compressor and the drier inlet ) will be
indicated by the discharge gauges reading excessively high. These simple tests can be
performed by a local shop and can help determine the extent of the systems problem.
TROUBLESHOOTING GUIDE
www.classicautoair.com • 866.435.7801