Acura RL. Manual - part 559

SYSTEM DESCRIPTION

The air conditioning system removes heat from the passenger compartment by transferring heat from the
ambient air to the evaporator. The evaporator cools the air with the refrigerant that is circulating through the
evaporator. The refrigerant expands in the evaporator, and the evaporator becomes very cold and absorbs the
heat from the ambient air. The blower fan pushes air across the evaporator where the heat is absorbed, and
then it blows the cool air into the passenger compartment.

Fig. 11: Air Conditioning Flow Diagram
Courtesy of AMERICAN HONDA MOTOR CO., INC.

This vehicle uses HFC-134a (R-134a) refrigerant, which does not contain chlorofluorocarbons. Pay attention
to the following service items:



Do not mix refrigerants CFC-12 (R-12) and HFC-134a (R-134a). They are not compatible.



Use only the recommended polyalkyleneglycol (PAG) refrigerant oil (DENSO ND-OIL 8) designed
for the R-134a A/C compressor. Intermixing the recommended (PAG) refrigerant oil with any other
refrigerant oil will result in A/C compressor failure.



All A/C system parts (A/C compressor, discharge line, suction line, evaporator, A/C condenser,

run with the A/C on) CIRCUIT TROUBLESHOOTING )

under-dash fuse/relay box



Cleanliness and tightness of all
terminals

HDS does not
communicate with
the climate control
unit or the vehicle

Troubleshooting the DLC circuit (see
DLC CIRCUIT
TROUBLESHOOTING )

2007 Acura RL

2005-08 HVAC HVAC - RL

Friday, June 05, 2009 2:25:42 PM

Page 19

receiver/dryer, expansion valve, O-rings for joints) are designed for refrigerant R-134a. Do not
exchange with R-12 parts.



Use a halogen gas leak detector designed for refrigerant R-134a.



R-12 and R-134a refrigerant servicing equipment are not interchangeable. Use only a
recovery/recycling/charging station that is U.L.-listed and is certified to meet the requirements of SAE
J2210 to service the R-134a air conditioning systems.



Always recover refrigerant R-134a with an approved recovery/recycling/charging station before
disconnecting any A/C fitting.

A/C Pressure Sensor

The A/C pressure sensor converts A/C pressure into electrical signals to the PCM.

Fig. 12: Identifying Sensor Unit
Courtesy of AMERICAN HONDA MOTOR CO., INC.

The response of the A/C pressure sensor is shown in the graph.

NOTE:

The pressures can be monitored using the HDS PGM-FI Data List.

2007 Acura RL

2005-08 HVAC HVAC - RL

Friday, June 05, 2009 2:25:42 PM

Page 20

Fig. 13: A/C Pressure And Output Voltage Graph
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Continuously Variable Capacity Compressor

When the shaft rotates, the slope plate rotates by means of the lug plate which is attached to the shaft. The
rotational movement of the slope plate is converted through the use of shoes to the reciprocal movement of
the pistons, which in turn take in, compress, and discharge the refrigerant.

The inner pressure of the slope plate chamber is controlled between low to mid range, and the pressure
determines the slope angle, determining the piston stroke as well and further controlling the discharge
amount, resulting in the continuously variable capacity.

The amperage to the variable capacity control solenoid valve is controlled to obtain continuously variable
low pressure, further achieving the continuous control of variable compressor capacity resulting in the
continuous control of the cooling capacity.

On/Off of the compressor clutch is eliminated in the system, hence no shock of the clutch
engaging/disengaging, and the idle speed becomes stable.

2007 Acura RL

2005-08 HVAC HVAC - RL

Friday, June 05, 2009 2:25:42 PM

Page 21

Fig. 14: Identifying Compressor Components
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Climate Control Door Positions

2007 Acura RL

2005-08 HVAC HVAC - RL

Friday, June 05, 2009 2:25:42 PM

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