JH CBC AUTO

A/C PERFORMANCE TESTING

CHAPTER 3Page 50-53

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PREPARATION

• Develop a consistent routine.• Use Common Sense Approach• Consult Service Manuals • Cleanliness• Safety• Windows Down

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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.

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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

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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

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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

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JH CBC AUTO

Be Cool Out There!!!