Honda Civic 2006 Service Manual

Heating/Air Conditioning System Description Without Climate Control (With A/C: Without Climate Control)

Heating/Air Conditioning System Description Without Climate Control

The air conditioning system removes heat from the passenger compartment by circulating refrigerant through the system.

 


EXPANSION VALVE
(Meters the required amount of
refrigerant into the evaporator)RECEIVER/DRYER
DESICCANT
(Traps debris, and
removes moisture)A/C COMPRESSOR
(Suction and compression)A/C CONDENSER
(Radiation of heat)A/C PRESSURE SENSOR
(Triple function)
When the refrigerant is below
196 kPa (2.0 kgf/cm2, 28 psi)
or above 3,140 kPa (32 kgf/cm2,
455 psi), the A/C pressure
switch opens the circuit to
the A/C switch and stops the
air conditioning to protect the
A/C compressor.
When the refrigerant is above
1,470 kPa (15.0 kgf/cm2, 213 psi),
the A/C pressure sensor
switches the radiator and
A/C condenser fans to high speed.BLOWER FANEVAPORATOR
(Absorption of heat)EVAPORATOR TEMPERATURE SENSORRELIEF VALVE
(Relieves pressure at the A/C compressor
when the pressure is too high)HIGH PRESSURE VAPORHIGH PRESSURE LIQUIDLOW PRESSURE LIQUIDLOW PRESSURE VAPOR

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 (SANDEN SP-10) 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, 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.

Oil Separator


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

 


EMISSION SIDE
(To A/C condenser)OIL SEPARATORFROM INSIDE
A/C COMPRESSORINHALATION SIDE
(To inside
A/C compressor)EVAPORATORA/C COMPRESSOROIL SEPARATORA/C CONDENSEREXPANSION VALVEMANY REFRIGERANT OIL FLOWLITTLE REFRIGERANT OIL FLOW

A/C Pressure Sensor


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

 


SENSOR UNIT

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

 


-99
(-1)
[-14]0196
(2)
[28]3,138
(32)
[455]kPa
(kgf/cm2)
[psi]V4.5750.6840.4250.2945OUTPUT
VOLTAGE
(Vout)Vcc 5 VVoutGNDA/C PRESSURE

Heating/Air Conditioning Door Positions

 


HOTCOOL(VENT)(HEAT/VENT)(HEAT)DEFROSTER
DOORAIR MIX
DOORHEAT/VENT
DOOR

 


HOTCOOL(HEAT/DEF)(DEF)

HVAC Control Unit Inputs and Outputs

 


HVAC CONTROL UNIT 24P CONNECTORWire side of female terminals

Cavity Wire color Signal 
1 BLK AIR MIX POTENTIAL +5 V OUTPUT 
2 BRN EVAPORATOR TEMPERATURE SENOR OUTPUT 
3 ORN MODE 1 OUTPUT 
4 LT GRN MODE 2 OUTPUT 
5 PUR MODE 3 OUTPUT 
6 BLU MODE 4 OUTPUT 
7 BLU BLOWER FEEDBACK INPUT 
8 YEL POWER TRANSISTOR CONTROL OUTPUT 
9 ——— ——— ——— 
10 ——— ——— ——— 
11 BRN*1 BLU*2 A/C SIGNAL OUTPUT 
12 RED ILLUMI (-) OUTPUT 
13 RED SENSOR COMMON GROUND INPUT 
14 WHT MODE VENT OUTPUT 
15 GRN MODE DEF OUTPUT 
16 ORN RECIRCULATE INPUT 
17 PUR*1 RED*2 FRESH INPUT 
18 GRY AIR MIX POTENTIAL OUTPUT 
19 LT BLU AIR MIX COOL OUTPUT 
20 PNK AIR MIX HOT OUTPUT 
21 BLK GROUND (G504) OUTPUT 
22 BRN*1 GRY*2 REAR WINDOW DEFOGGER RELAY INPUT 
23 LT GRN*1 PUR*2 IG2 (Power) INPUT 
24 GRY ILLUMI (+) INPUT 

*1: LHD type 
*2: RHD type