heating and a/c system descri

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HEATING AND A/C SYSTEM DESCRI...

2009 CR-V - - Heating and A/C System Description

The air conditioning (A/C) system removes heat from the passenger compartment by transferring heat from theambient air to the evaporator. The A/C refrigerant expands in the evaporator, and the evaporator becomes verycold and absorbs the heat from the ambient air. The blower fan pushes air across the evaporator where the heat isabsorbed, and then it blows the cool air into the passenger compartment.

This vehicle uses HFC-134a (R-134a) refrigerant, which does not contain chlorofluorocarbons. Pay attention to thefollowing 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 (SP-10) designed for the R-134a A/Ccompressor. Intermixing the recommended (PAG) refrigerant oil with any other refrigerant oil will result inA/C compressor failure.

All A/C system parts (A/C compressor, discharge line, suction line, evaporator, A/C condenser,receiver/dryer, expansion valve, O-rings for joints) are designed for refrigerant R-134a. Do not exchangewith 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 arecovery/recycling/charging station that is U.L.-listed and is certified to meet the requirements of SAEJ2210 to service the R-134a air conditioning systems.



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

Oil Separator

Oil emission from the A/C compressor to the A/C line is reduced by placing the oil separator in the A/Ccompressor. This results in a thinner oil film inside of the heat exchangers (A/C condenser and evaporator). Airconditioning efficiency is increased without sacrificing engine performance.

A/C Pressure Sensor

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



A/C System Pressure* SensorOutput

Voltage (Vout)

System OperationA/C System Pressure* SensorOutput

Voltage (Vout)

System Operation

Abnormally low pressure:Below 196 kPa(2.0 kgf/cm2, 28 psi)

Below 0.685V

The PCM disengages the compressorclutch. The radiator and condenserfans operate based on engine coolanttemperature.

Normal operating pressure:

Above 196 kPa (2.0kgf/cm2, 28 psi)

Below 1,470 kPa (15.0kgf/cm2, 213 psi)

0.686 V to1.944 V

The PCM cycles the compressorclutch based on cooling demand. Theradiator and condenser fans operateat low speed unless the enginecoolant temperature exceeds 206 °F(97 °C)

High operating pressure:

Above 1,470 kPa (15.0kgf/cm2, 213 psi)

Below 3,138 kPa (32kgf/cm2, 455 psi)

1.945 V to4.575 V

The PCM cycles the compressorclutch based on cooling demand. Theradiator and condenser fans operateat high speed.

Abnormally high pressure:More than 3,138 kPa (32kgf/cm2, 455 psi)

Above 4.575V

The PCM disengages the compressorclutch. The radiator and condenserfans operate based on engine coolanttemperature.

*: The A/C system pressure can be monitored through the climate control sensor inputdisplay function.

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

NOTE: When the refrigerant is below 196 kPa (2.0 kgf/cm2, 28 psi) or above 3,138 kPa (32 kgf/cm2, 455 psi), thePCM turns the compressor relay off to protect the A/C compressor. When the refrigerant pressure is above 1,470kPa (15.0 kgf/cm2, 213 psi), the PCM switches the radiator and A/C condenser fans to high speed.



Heating/Air Conditioning Door Positions



HVAC Control Unit Inputs and Outputs

CONNECTOR A

Cavity Wirecolor

Terminal name Description Signal



Cavity Wirecolor


3 ORN Mode controlmotor 1 Mode control motor position

feedback

With ignition switch ON (II), or vehicle inON mode: about 0 V or about 5 V

(depending on motor position)

4 LT GRN Mode controlmotor 2 Mode control motor position

feedback



5 PUR Mode controlmotor 3 Mode control motor position

feedback



6 LT BLU S5V Power source for sensors With ignition switch ON (II): about 5.0 V

7 BLU Mode controlmotor 4 Mode control motor position

feedback



8 GRY Air mix controlmotor

Detects air mix potentialsignal

With ignition switch ON (II): about 0.5－4.5V (depending on AIR MIX MOTOR position)

9 BRN EvaporatorTemperatureSensor

Detects evaporatortemperature sensor signal

With ignition switch ON (II), or vehicle inON mode: between 1.0 V and 4.0 V

(depending on evaporator temperature).About 2.5 V at 72 °F (22 °C)

10 WHT ACS A/C signal

11 BLU Blower Feedback Feedback signal fromblower power resistor

With ignition switch ON (II), or vehicle inON mode, and fan switch OFF: about 8 V.Voltage decreases as fan speed increases

12 RED Blower TransistorControl Outputs blower power

resistor gate voltage

With ignition switch ON (II), or vehicle inON mode, and fan switch at MIN: about 4

V. Voltage increases to about 12 V with fanswitch at MAX

14 GRN Illumination (-) Detects illumination controlsignal

With combination light switch ON: voltagevaries as dashlights brightness varies

18 BLK Ground for HVACcontrol unit (G503)

Ground for control unit(G503)

Less than 0.5 V at all times

19 LT GRN Sensor ground Common ground for sensors Less than 0.5 V at all times



Cavity Wirecolor


20 LT GRN Rear windowdefogger relay

Input rear window defoggerrelay

21 GRN Recirculationcontrol motor(REC)

Drives recirculation controlmotor to RECIRCULATE

With ignition switch ON (II), or vehicle inON mode, and motor moving toRECIRCULATE: battery voltage

22 WHT Recirculationcontrol motor(FRS)

Drives recirculation controlmotor to FRESH

With ignition switch ON (II), or vehicle inON mode, and motor moving to FRESH:

battery voltage

23 PNK Air mix controlmotor (HOT) Drives air mix control motor

to HOT

With ignition switch ON (II), or vehicle inON mode, and motor moving to HOT:

battery voltage

24 LT BLU Air mix controlmotor (COOL) Drives air mix control motor

to COOL

With ignition switch ON (II), or vehicle inON mode, and motor moving to COOL:

battery voltage

25 LT GRN Mode controlmotor (VENT) Drives mode control motor

to VENT

With ignition switch ON (II), or vehicle inON mode, and motor moving to VENT:

battery voltage

26 GRN Mode controlmotor (DEF) Drives mode control motor

to DEF

With ignition switch ON (II), or vehicle inON mode, and motor moving to DEF:

battery voltage

27 BRN IG2 (Power) IG2 Power source With ignition switch ON (II), or vehicle inON mode: battery voltage

28 GRY Illumination (+) Input voltage forillumination

With combination light switch ON: batteryvoltage

Portions of materials contained herein are sourced from American Honda Motor Inc., Co.

Copyright 2009 - 2013 Service Repair Solutions, Inc.

heating and a/c system descri

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