Ac System
SCHEMATIC EXPLANATION OF AC FUNCTION
AIR CONDITION COMPONENTS
Receiver Drier Evaporator with
with Pr. switch blower and antifreeze
thermostat
Condenser Drive Belt
Expansion
Valve
Liquid Line Hose
Compressor/Clutch
Assembly
Suction Hose
Discharge Hose
AIR CONDITION COMPONENTS
1. COMPRESSOR:
Pumps the refrigerant through the system
It draws in refrigerant as a vapour and compresses it.
Increase in both temperature and pressure
Refrigerant Leaves the compressor as high pressure,
high temperature vapour.
Compressor Lubrication
• Extra oil required depends on system size
• Oil suspended in refrigerant.
• Only approx. 5% of mixture is oil
• Extremely hydroscopic
• Containers must always be kept sealed.
AIR CONDITION COMPONENTS
2. CLUTCH:
Engages or disengages compressor.
Uses electrical power to operate.
Requires a minimum of 23 volts (for a 24V system) to keep from slipping and
being destroyed by excessive heat.
Clutch Performance
• Insufficient voltage to clutch causes slippage
and heat resulting in inevitable clutch failure.
• Turn on all electrical systems when measuring.
• Check belt tension.
• 12 Volt system
o 11.5 -14 Volts
o Clutch should pull around 4 amps
• 24 Volt system
o 24-26 Volts
o Clutch should pull around 2 amps.
AIR CONDITION COMPONENTS
3. CONDENSER:
Removes (dissipates) heat.
Condenses gas back into a liquid.
Refrigerant Leaves as high pressure
subcooled liquid.
Types of Condenser (based on mount):
• Radiator mount condenser.
• Remote mount condenser.
• Roof mount condenser.
• Evaporator & condenser.
AIR CONDITION COMPONENTS
4. RECEIVER DRIER:
Filters the refrigerant.
Dries the refrigerant.
Act as a reservoir for the liquid.
Refrigerant Leaves as high-pressure,
clean, dried and subcooled liquid.
R-134a + water = hydrofluoric acid
Receiver Drier Service Tips:
• Driers must be replaced every time
the system is opened.
• Frost appearing on drier canister indicates
an internal restriction.
• A properly functioning drier should be warm
to the touch.
AIR CONDITION COMPONENTS
5. EXPANSION VALVE:
Thermal expansion valve:
• Temperature of refrigerant leaving.
• Evaporator sensed by temp bulb/TXV.
• Meters the amount entering evaporator.
• Refrigerant Leaves as low pressure
saturated vapour.
AIR CONDITION COMPONENTS
6. EVAPORATOR:
Refrigerant injected into evaporator
by TXV.
Absorbs heat from air.
Air is cooled, dried and cleaned.
Refrigerant Leaves evaporator as
low pressure vapour.
AIR CONDITION COMPONENTS
7. THERMOSTAT:
Senses evaporator temperature to prevent
evaporator freeze-up.
Thermostat Placement
• Insert thermostat to correct
depth.
• Must not be loose.
Thermostat Failures:
• Capillary tube broken, loss of gas charge.
• Electrical shorts.
• Out of calibration.
• Voltage / Ground Issues.
AIR CONDITION COMPONENTS
8. PRESSURE SWITCHES:
Service Ports
Discharge
Suction
Service Ports Sealing Cap
Sealing Cap
Compressor Installation
Oil plug should be on top or rotated
no more than 90 to allow proper oil
circulation within the compressor.
Procedures and Equipment
• Compressor preparation
• Evacuation
• Charging
• Leak testing
• Preventative maintenance.
Compressor Preparation
• Calculate oil required.
• 135cc up to 15 ft.
• Add 30cc for every additional 7 ft.
• Max 300cc.
Adding Oil When Replacing Components
Some oil will remain in the component that is being replaced,
so there is a need to replace that lost oil in the system
