Climate Control System : Notes

WARNING: This page is about a different car, the 2004 Mercury Marauder, 2004 Mercury Grand Marquis, and 2004 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: To avoid accidental deployment and possible injury, the air bag system backup power supply must be depleted before repairing any climate control components. To deplete the backup power supply, disconnect the battery ground cable and wait one minute. Failure to follow these instructions can result in personal injury.

WARNING: Carbon monoxide is colorless, odorless and dangerous. If it is necessary to operate the engine with vehicle in a closed area such as a garage, always use an exhaust collector to vent the exhaust gases outside the closed area. Failure to follow these instructions can result in personal injury.

WARNING: R-134a is classified as a safe refrigerant, but misuse can make it dangerous. The following precautions must be observed. Failure to follow these instructions can result in personal injury.

Always wear safety goggles when repairing an air conditioning system.
Avoid contact with liquid refrigerant R-134a. R-134a vaporizes at approximately -25°C (-13°F) under atmospheric pressure and it will freeze skin tissue.
Never allow refrigerant R-134a gas to escape in quantity in an occupied space. R-134a is nontoxic, but it will displace the oxygen needed to support life.
Never use a torch in an atmosphere containing R-134a gas. R-134a is non-toxic at all normal conditions, but when it is exposed to high temperatures, such as a torch flame, it decomposes. During decomposition it releases irritating and toxic gases (as described in MSDS sheet from the manufacturer). Decomposition products are hydrofluoric acid, carbon dioxide and water.
Do not allow any portion of the charged air conditioning system to become too hot. The pressure in an air conditioning system rises as the temperature rises and temperatures of approximately 85°C (185°F) can be dangerous.
Allow the engine to cool sufficiently prior to performing maintenance or serious burns and injury can occur.

CAUTION: To avoid damaging the vehicle or A/C components, the following precautions must be observed.

The A/C refrigerant of all vehicles must be identified and analyzed prior to refrigerant charging. Failure to do so can contaminate the shop bulk refrigerant and other vehicles.
Do not add R-12 refrigerant to an air conditioning system that requires the use of R-134a refrigerant. These two types of refrigerant must never be mixed. Doing so can damage the air conditioning system.
Charge the air conditioning system with the engine running only at the low-pressure side to prevent refrigerant slugging from damaging the A/C compressor.
Use only R-134a refrigerant. Due to environmental concerns, when the air conditioning system is drained, the refrigerant must be collected using refrigerant recovery/recycling equipment. Federal law REQUIRES that R-134a be recovered into appropriate recovery equipment and the process be conducted by qualified technicians who have been certified by an approved organization, such as MACS, ASI, etc. Use of a recovery machine dedicated to R-134a is necessary to reduce the possibility of oil and refrigerant incompatibility concerns. Refer to the instructions provided by the equipment manufacturer when removing refrigerant from or charging the air conditioning system.
Refrigerant R-134a must not be mixed with air for leak testing or used with air for any other purpose above atmospheric pressure. R-134a is combustible when mixed with high concentrations of air and higher pressures.
A number of manufacturers are producing refrigerant products that are described as direct substitutes for refrigerant R-134a. The use of any unauthorized substitute refrigerant can severely damage the A/C components. If repair is required, use only new or recycled refrigerant R-134a.

CAUTION: To avoid contamination of the A/C system, observe the following precautions:

Never open or loosen a connection before recovering the refrigerant using approved equipment.
When loosening a connection, if any residual pressure is evident, allow it to leak out before opening the fitting.
Evacuate a system that has been opened to install a component or one that has discharged through leakage before charging.
Seal open fittings with a cap or plug immediately after disconnecting a component from the system.
Clean the outside of the fittings thoroughly before disconnecting a component from the system.
Do not remove the sealing caps from a new component until ready to install.
Refrigerant oil will absorb moisture from the atmosphere if left uncapped. Do not open an oil container until ready to use, and install the cap immediately after using. Store the oil in a clean, moisture-free container.
Install a new O-ring seal before connecting an open fitting. Coat the fitting and O-ring seal with refrigerant oil before connecting.
When installing a refrigerant line, avoid sharp bends. Position the line away from the exhaust or any sharp edges that can chafe the line.
Tighten threaded fittings only to specification. The steel and aluminum fittings used in the refrigerant system will not tolerate overtightening.
When disconnecting a fitting, use a wrench on both halves of the fitting to prevent twisting of the refrigerant lines or tubes.
Do not open a refrigerant system or uncap a new component unless it is as close as possible to room temperature. This will prevent condensation from forming inside a component that is cooler than the surrounding air.

The manual climate control system heats or cools the vehicle depending on the function selector switch position and the temperature selected.

The function selector switch position determines heating or cooling and air distribution.
The temperature control setting determines the air temperature.
The heater blower motor switch varies the blower motor speed.

The electronic automatic temperature control system maintains the selected vehicle interior temperature by heating or cooling the air.

During A/C operation, the system also reduces the relative humidity of the air.
The driver may override the automatic mode of operation.