Air Conditioning System Precautions

General

The air conditioning system contains fluids and components which could be potentially hazardous to the technician or the environment if not serviced and handled correctly. The following guidelines are intended to alert the technician to potential sources of danger and emphasize the importance of ensuring the integrity of the air conditioning operating conditions and components fitted to the vehicle.

Where necessary, additional specific precautions are detailed in the relevant sections of this Manual which should be referred to prior to commencing repair operations.

The refrigerant used in the air conditioning system is R134a or R1234yf.

Warning: Servicing must only be carried out by personnel familiar with both the vehicle system and the charging and testing equipment. All operations must be carried out in a well-ventilated area away from open flame and heat sources.

Warning: Refrigerant is a hazardous liquid and when handled incorrectly can cause serious injury. Suitable protective clothing, consisting of face protection, heat-proof gloves, rubber boots and apron or waterproof overalls, must be worn when carrying out operations on the air conditioning system.

Remedial actions

Warning: Due to its low evaporating temperature, refrigerant must be handled with care. Refirgerant splashed on any part of the body will cause immediate freezing of that area.

If an accident involving refrigerant should occur, conduct the following remedial actions:

If liquid refrigerant enters the eye, do not rub it. Gently run large quantities of eye wash over affected eye to raise the temperature. If an eye wash is not available, cool, clean water may be used to flush the eye. After rinsing, cover the eye with a clean pad and seek immediate medical attention.
If liquid refrigerant is splashed onto the skin, run large quantities of water over the affected area to raise the temperature. Implement the same action if the skin comes in contact with discharging cylinders. Wrap the contaminated body parts in blankets (or similar materials) and seek immediate medical attention.

Service precautions

Observe the following precautions when handling components used in the air conditioning system:

Air conditioning units must not be lifted by their hoses, pipes or capillary lines.
Hoses and lines must not be subjected to any twist or stress; the efficiency of the system will be impaired by kinks or restrictions. Ensure that hoses are correctly positioned before tightening couplings, and ensure that all clips and supports are utilized.
Completed assemblies must be checked for refrigeration lines touching metal panels. Any direct contact of components and panels may transmit noise and so must be eliminated.
The appropriate torque wrench must be used when tightening refrigerant connections to the stipulated value. An additional wrench must be used to hold the union to prevent twisting of the pipe when tightening connections.
All protective plugs must remain in place to seal the component until immediately prior to connection.
Ensure components are at room temperature before uncapping, to prevent condensation of moisture from the air that enters it.
Components must not remain uncapped for longer than 15 minutes. In the event of a delay, the caps must be fitted.
When disconnecting, immediately cap all air conditioning pipes to prevent ingress of dirt and moisture into the system.
The receiver/drier contains desiccant which absorbs moisture. It must be positively sealed at all times. A receiver/drier that has been left uncapped must not be used.
The receiver/drier should be the last component connected to the system to ensure optimum dehydration and maximum moisture protection of the system.
Use alcohol and a clean, lint-free cloth to clean dirty connections.
Ensure that all new parts fitted are suitable for use with the specified refrigerant.

HVAC line installation

Always carry out the following procedure before connecting any hose or pipe:

All refrigeration fittings require oiling with the recommended refrigerant oil before installation. Refer to General Information > Fluids and Capacities > Fluids.
When connecting refrigeration fittings, ensure that the O-ring is positioned correctly. Push the joint together until the O-ring disappears before attempting to tighten the nut. The nut should start by hand; if a wrench is required then the joint is misaligned. Tighten the joint to the torque shown.
The refrigeration system must be kept clean and capped at all stages. At no time must any hoses be left open to atmosphere as the oil in the system is hygroscopic (absorbs moisture). The connection to the drier should only be completed just prior to commissioning (or at least the system should be vacuumed to keep the system dry so any moisture generally in the pipe work does not affect the oil or ‘wet’ the receiver drier).
Keep the lid on oil containers such that a small amount can be dispensed at any time and then at the end of the week, the whole can is disposed of to avoid using contaminated oil. Oil containers kept to lubricate O-rings should not be used to top up oil in systems due to potential contamination.

Use the HVAC machine to perform a leak test after a major repair has been completed.

Refrigerant oil

The compressor contains a lubricant, which has greater electrical insulating properties than the A/C lubrication oil normally used for standard mechanical belt driven A/C pumps. It is important that the compressor is kept upright at all times to retain the lubricant in the compressor’s sump.

Caution: Use of the incorrect oil may affect the dielectric strength of the motor and potentially cause an internal short circuit as well potentially affecting the bearing life.

Caution: Refrigerant oil easily absorbs water and must not be stored for long periods. Do not pour unused refrigerant oil back into the container.

Compressor

A new compressor is sealed. Ensure that no foreign material is allowed to enter the compressor.

Caution: Do not remove the cap(s) until immediately prior to connecting the air conditioning pipes to the compressor. Foreign material entering the compressor is likely to cause significant damage requiring replacement.

Rapid refrigerant discharge

If the air conditioning system is involved in accident damage and the system is punctured, the refrigerant will discharge rapidly. The rapid discharge of refrigerant will also result in the loss of most of the oil from the system. The compressor must be removed and all the remaining oil in the compressor drained and refilled as instructed in the air conditioning section of this manual.

Refrigerant evacuation and recharging

The HVAC and battery coolant circuits are sealed to prevent the discharge of refrigerant. The refrigerant must be recovered before any removal of system components using the recommended equipment.

Two ports are provided on the HVAC system and are accessible under the hood.

Warning: Ensure that all safety precautions have been taken and the HVAC and battery circuits have been placed in service mode (see below) prior to any attempts to evacuate the system.

High pressure remote charging port

This port is fitted onto the pipe directing the high pressure refrigerant gas from the compressor to the condenser. It can be accessed under hood from the RH side of the vehicle adjacent to the RH suspension shock tower strut brace. A Schraeder valve forms the port in the pipe allowing the connection of charging/discharging equipment for servicing purposes. The connection is a 16 mm quick coupler. The valve is fitted with a screw-on cap to prevent seepage of refrigerant through the valve and also to exclude dirt.

Low pressure remote charging port

This pipe leads back from the evaporator. It can be accessed under hood, from the RH side of the vehicle adjacent to the HP Schraeder valve. It forms a port at the top of the pipe which allows the connection of recovery/charging equipment for servicing purposes. The connection is a 13mm quick coupler. The valve is fitted with a screw-on cap to prevent seepage of refrigerant through the valve and also to exclude dirt.

HVAC system service mode

The vehicle uses two separate circuits, one circuit for the evaporator situated in the HVAC assembly for the cabin environment, and an additional circuit for the battery heat exchanger.

Both of these circuits have solenoid valves controlled by the thermal controller module. During A/C evacuation and recharge it is important to open these solenoids manually (service mode). This will ensure that all refrigerant is removed and replaced from both circuits during evacuating and recharge of the system.

Warning: HVAC service mode must be initiated using Toolbox before any evacuation and recharge procedures are performed. Refer to Service Manual procedure 18200102.

With the vehicle in service mode, the refrigerant can be recovered or recharged. The HVAC system will stay in service mode until the mode is exited using Toolbox or the laptop is disconnected from the vehicle.

Warning: It is important that the key remains in the vehicle during evacuation or recharge. If it is removed, service mode will be disabled, thus closing the solenoids, which means that there is a risk that the HVAC lines may not be fully evacuated or filled during recharge.

Note: When in service mode, all normal HVAC system operation is disabled apart from operation of the battery coolant pump.

Debris or moisture in the A/C system

Internally or externally damaged components can cause debris and moisture to enter the A/C system. Perform the following procedures if debris or excessive moisture ingress is suspected.

Caution: Do not attempt to use an A/C refrigerant flushing kit with Model S and Model X.

A/C components damaged in a collision, no refrigerant leakage

If no refrigerant leaked from the system, the A/C compressor likely did not run low on refrigerant, so there should be no debris in the A/C system.

Evacuate the refrigerant.
Replace damaged components.
Use the HVAC machine to perform a leak test.
Recharge the refrigerant.

A/C components damaged in a collision, refrigerant leakage

If refrigerant leaked from the system, the A/C compressor likely ran with little to no refrigerant. This could damage the compressor internally, leading to debris in the system.

Evacuate the refrigerant.
Replace the A/C compressor, the sub-cool (RH) condenser, and all components between them: A/C compressor, discharge line, gas-cool (LH) condenser, condenser 1 to condenser 2 line, sub-cool (RH) condenser, and receiver/drier desiccant bag.
Replace damaged components.
Use the HVAC machine to perform a leak test.
Recharge the refrigerant.

A/C system was left open to the environment for an extended time

Ambient moisture entering the system has depleted the receiver/drier dessicant. Debris might have entered the end connections of the open components.

Replace the components that have end connections that were left open.
Replace the receiver/drier desiccant bag.
Recharge the refrigerant.

Precautions for refrigerant recovery, recycling and recharging

When the air conditioning system is discharged/recharged, any existing refrigerant is recovered from the system and recycled. The system is then charged with the required weight of refrigerant and new oil equal in volume to the oil recovered.

Warning: Refrigerant must always be recycled before re-use to ensure that the purity of the refrigerant is high enough for safe use in the air conditioning system.

Warning: Recycling should always be carried out with the recommended equipment. Other equipment may not recycle refrigerant to the required level of purity.

Warning: Never mix different types of refrigerants.

Caution: The system must be evacuated immediately before recharging commences. Delay between evacuation and recharging is not permitted.