JH CBC AUTO
A/C PERFORMANCE TESTING
CHAPTER 3Page 50-53
JH CBC AUTO
PREPARATION
• Develop a consistent routine.• Use Common Sense Approach• Consult Service Manuals • Cleanliness• Safety• Windows Down
JH CBC AUTO
VISUAL INSPECTION
• Inspect under hood for SIGNS OF LEAKAGE/HOSE CONDITION
• Inspect CONDENSER for signs of damage
• Inspect COMPRESSOR BELT condition• Inspect COOLING SYSTEM condition• Inspect A/C Controls Function
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STABILIZE SYSTEM
• Make sure Manifold Gauge set valves are shut before hooking up to system
• Connect to the system• Start Engine and Run 1500 - 1700 rpm• Let Engine get to full operation temp• Turn on A/C and set blower to high and
set A/C system to max A/C• Put thermometer in A/C duct inside car.
JH CBC AUTO
Manifold Gauge Set
• A Manifold Gauge Set• 3 Pressure Hoses• Low Side (blue hose) Compound Gauge -
vacuum to approx. 250 PSI• High Side (red hose) Gauge - 0 to
approx.. 500 PSI• Two separate Hand Valves• Some Gauges can be calibrated
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Manifold Gauge Set Operation
• Pressure Check of System - both valves closed
• Charging with Refrigerant - Low side open
• Evacuation - Both valves open
Page 5L
JH CBC AUTO
GAUGE PRESSURE CHECK• Low side average: 20 to 30 PSI• High side average: 160 to 220 PSI • High side “rule of thumb”: Add 100 PSI to
ambient temperature example: It’s 80 degrees outside, add 100 PSI. approximate high side pressure should be 180 PSI
• Discharge temperature should be within specified range for system. (35 to 50 degree)
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“HAND FEEL CHECK”
• RULE OF THUMB: – All high side hoses and components should
be warm to touch– All low side hoses and components should be
cool to the touch
• Note condition of TXV or FOT– Is is frosted on inlet side = bad valve or
orifice or moisture in system
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QUICK “FEEL” CHECK• If ambient temp above 70 degrees F• Engine warm and at idle• Max A/C and High Blower• feel evaporator inlet pipe and
accumulator– Both same temp and cooler than ambient -
OK– inlet pipe cooler than accumulator - Low
charge– Inlet pipe warmer than evap outlet -
overcharge
JH CBC AUTO
Hand Tools You Will Use• Thermometer• Leak Detector• Vacuum Pump• Snap Ring Pliers• Seal Installers/Removers• Safety Glasses• Can Taps and Hose Adapters (pg.. 49L)• Shut Off Valve Service Hose (pg. 46L)
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TEST CONTROL DEVICES• Refer to Service
Manual • Relative Humidity • Pg. 8C and 53L• Make sure if FOT
system that clutch is cycling (norm temp)
• Can test Expansion Valve if accessible
• Condenser Fan Operation
JH CBC AUTO
JH CBC AUTO
Be Cool Out There!!!