Explain to students that heating and air conditioning systems are prone to failure. Even the smallest leak (refrigerant or coolant) will eventually keep either system from working properly. Let them know that correct service methods not only keep the vehicle operating normally, but they help protect our environment from damage caused by refrigerant gases and antifreeze spillage.
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Instruct students that the following are some basic information tips that can help them Identify and interpret some of the most common problems found in heating and air conditioning systems. Inform them that knowledge of these will help to increase their employability in almost any automotive repair facility.
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ISSUES TO LOOK FOR IN THE AIR CONDITIONING SYSTEM:
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IF THERE IS NO COOLING, tell students to look for the following, and apply the suggested repair: * Low refrigerant/Add Refrigerant. * Refrigerant leak/Repair leak and recharge. * Bad compressor/Replace Compressor. * Compressor not engaging/Repair Clutch or Sensors. * Missing drive belt/Install Belt. * Bad control circuit/Test and repair the circuit.
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IF THERE IS POOR COOLING, tell students to look for the following and apply the suggested repair: * Low refrigerant/Add Refrigerant. * Blower will not work on high/Repair the Blower Circuit. * Bad air control system/Repair the Flap System. * Debris in condenser/Clean the Condenser fins. * Belt slippage/Tighten Compressor belt.
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IF STUDENTS HAVE GAUGES HOOKED UP TO THE A/C SYSTEM, AND THE LOW SIDE PRESSURE IS HIGH, have students look for the following and apply repair: * Bad expansion valve/Replace the valve. * Moisture in system/Replace Desiccant and Recharge. * Compressor problems/Replace the Compressor. * Restricted suction line/Replace the suction line.
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If the LOW SIDE PRESSURE IS LOW, check for and apply: * Low refrigerant/Charge system. * Low airflow/Clean Condenser fins and check the blower operation. * Restricted liquid line/Replace the line. * Restricted suction line/Replace the line. * Compressor not disengaged/Repair the frozen clutch, bad sensor or control circuit
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IF THE HIGH SIDE PRESSURE IS HIGH, tell students to check for and apply: * Low refrigerant, air in system/Evacuate the system and recharge. * System overcharged/Properly charge the system. * Clogged condenser core/Replace the condenser. * Engine overheating/Repair the cooling system. * Refrigerant system restriction/Replace parts that are causing the restriction.
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IF THE HIGH SIDE PRESSURE IS LOW, check for and apply: * Low refrigerant charge/Charge the system. * Expansion valve open/Replace the valve. * Bad compressor/Replace the compressor.
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ISSUES TO LOOK FOR IN THE HEATING SYSTEMS:
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IF THERE IS NO HEATING, tell students to look for the following and apply the suggested repair: * Blown blower fuse/Replace Fuse and repair circuit if necessary. * Open blower switch/Replace the switch. * Bad blower motor/Replace Motor. * Fan loose on shaft/Repair the Fan. * Open wiring/Repair open Circuit * Inoperative flow valve/Repair or replace coolant valve at heater hose.
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IF THERE IS POOR HEATING, check for and apply repair: * Clogged heater core/Flush or Replace the Heater Core. * Inoperative flow valve/Repair or replace coolant valve at heater hose. * Blower will not work on high/Repair blower motor circuit. * Open thermostat/Replace the Thermostat. * Low engine coolant level/ Add Coolant. * Air in cooling system/Bleed out the air. * Airflow doors inoperative/Repair controls and doors if necessary.
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IF THERE IS INADEQUATE DEFROST, check for and apply repair: * Air flap problem/Adjust air flaps or repair circuit. * Disconnected ducts/Reinstall the ducts. * Blockage in ducts/Remove the debris.
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THE DEFROST MODE FOGS THE WINDSHIELD check for and apply: * AC not working/Repair AC system. * Leaking heater core/Replace Heater Core. * Leaking windshield seal/Replace the seal or caulk the glass.
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IF THEY HEAR AN ABNORMAL NOISE, tell students to look for the following and apply the suggested repair: * Bad compressor/Replace the compressor. * Too much refrigerant/Install the correct charge. * Belt slippage/Adjust belt tension. * Compressor cycling/Add refrigerant or repair control system. * Loose parts/Tighten hold downs. * Bad blower bearings/Replace the Blower Motor. * Loose fan/Install or replace the blower fan.
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IF STUDENTS SEE WATER/COOLANT ON THE FLOORBOARD, have them check for the following and apply the suggested repair: * Leaking heater core/Replace the core. * Loose heater hose clamps/Tighten the clamps. * Evaporator drain clogged/Clean out the drain tube.
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