2002 MAZDA 6 heater

U–6
CONTROL SYSTEM
WATER HEATER SYSTEMA6E854000169201Outline
•The function, structure and operation of the water heater system is essentially carried over from that of the
current MPV (LW) model, except for following:
—Full/half switching temperature has been changed.
Structural View
.
Operation
Full/half switching
•Depending on the engine coolant temperature, the CPU sets the flame to either full or half strength settings.
.
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CONTROL SYSTEM
1
2
A6E85402002
1 Water heater unit2 Fuel pump (water heater system)
3
1
2
68
{154}74
{165}75
{167}78
{172}˚C
{˚F}
A6E85402003
1 Full mode
2 Half mode3 Idle mode

OUTLINE
U–7
U
SUPPLEMENTAL SERVICE INFORMATIONA6E850201038204•The following additions have been made for the MZR-CD (RF Turbo) since the publication of the Mazda6
Workshop Manual (1730-1*-02C).
A/C unit
•Removal/installation procedure has been modified.
A/C compressor
•Removal/installation procedure has been modified.
Condenser
•Removal/installation procedure has been modified.
Refrigerant lines
•Removal/installation procedure has been modified.
Water heater unit
•Removal/installation procedure has been added.
Fuel pump (water heater system)
•Inspection procedure has been added.
Climate control unit
•Inspection procedure has been modified.
Water heater system
•On-board diagnostic system has been added.
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OUTLINE

U–8
LOCATION INDEX
BASIC SYSTEMA6E850001040201
.
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LOCATION INDEX
8
75
4
3
1
2
6
4
L.H.D.
A6E85002001
8
7
5
43
1
2
6
4
R.H.D.
A6E85002002
1 Blower unit
2 Air filter
3A/C unit
(See U–10 A/C UNIT REMOVAL/INSTALLATION)
4 Rear heat duct
5 A/C compressor
(See U–11 A/C COMPRESSOR REMOVAL/
INSTALLATION)6 Condenser
(See U–12 CONDENSER REMOVAL/
INSTALLATION)
7Heater hose
8 Refrigerant lines
(See U–13 REFRIGERANT LINES REMOVAL/
INSTALLATION)

LOCATION INDEX
U–9
U
CONTROL SYSTEMA6E850001040202
.
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1
2
3
A6E85002003
1 Water heater unit
(See U–15 WATER HEATER UNIT REMOVAL/
INSTALLATION)
2 Fuel pump (water heater system)
(See U–16 FUEL PUMP (WATER HEATER
SYSTEM) INSPECTION)3 Climate control unit
(See U–16 CLIMATE CONTROL UNIT
INSPECTION)

U–10
BASIC SYSTEM
A/C UNIT REMOVAL/INSTALLATIONA6E8516611302011. Disconnect the negative battery cable.
2. Discharge the refrigerant from the system.
3. Drain the engine coolant.
4. Remove the dashboard.
5. Remove the theft-deterrent control module.
Caution
•If moisture or foreign material enters the refrigeration cycle, cooling ability will be lowered and
abnormal noise will occur. Always immediately plug open fittings after removing any refrigeration
cycle parts to keep moisture or foreign material out of the cycle.
6. Remove in the order indicated in the table. Do not allow compressor oil to spill.
.
BASIC SYSTEM
1
L.H.D.R.H.D.
3
2
R
R
N·m {kgf·cm, in·lbf} 6.86—9.80
{70.0—99.9,
60.8—86.7}
R
R
3
2
1
4
A6E85162001
1 Heater hose
2 Cooler pipe No.4 (L.H.D.) or cooler pipe No.5
(R.H.D.)
(See U–13 REFRIGERANT LINES REMOVAL/
INSTALLATION) (R.H.D.)
(See U–13 REFRIGERANT LINES REMOVAL/
INSTALLATION)3 Cooler pipe No.3
(See U–13 REFRIGERANT LINES REMOVAL/
INSTALLATION) (R.H.D.)
(See U–13 REFRIGERANT LINES REMOVAL/
INSTALLATION)
4A/C unit
(See U–11 A/C Unit Installation Note)

BASIC SYSTEM
U–13
U
REFRIGERANT LINES REMOVAL/INSTALLATIONA6E8516614602011. Remove the battery.
2. Discharge the refrigerant from the system.
3. Remove the washer tank.
4. Remove the air cleaner cover, air cleaner element and air cleaner case. (See F2–36 INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
5. Remove the sedimentor.
6. Remove the No.3 engine mount.
7. Remove the water heater unit.
8. Remove the shroud panel.
9. Remove the right splash shield.
Caution
•If moisture or foreign material enters the refrigeration cycle, cooling ability will be lowered and
abnormal noise will occur. Always immediately plug all open fittings after removing any
refrigeration cycle parts to keep moisture or foreign material out of the cycle.
10. Remove in the order indicated in the table. Do not allow compressor oil to spill.
11. Install in the reverse order of removal.

BASIC SYSTEM, CONTROL SYSTEM
U–15
U
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WATER HEATER UNIT REMOVAL/INSTALLATIONA6E854000170201
Caution
•If the negative battery cable is disconnected during the purge cycle of the water heater unit, the
gas in the unit may not be properly scavenged, causing white smoke (unburnt gas) to emit from
the exhaust pipe. Before disconnecting the negative battery cable, verify that the water heater unit
is not operating (no blower fan operation noise).
1. Complete the “BEFORE REPAIR PROCEDURE”. (See F2–45 BEFORE REPAIR PROCEDURE.)
2. Disconnect the negative battery cable.
3. Drain the engine coolant.
4. Remove the fuel filter with the pipes still connected, and fix the fuel filter using a rope so that it is out of the way.
5. Remove in the order indicated in the table.
6. Install in the reverse order of removal.
7. Complete the “AFTER REPAIR PROCEDURE”. (See F2–45 AFTER REPAIR PROCEDURE.)
8. Refill the engine coolant.
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1 Cooler pipe No.1
2 Cooler pipe No.2
3 Cooler pipe No.3
4 Cooler pipe No.45 Cooler pipe No.5 (R.H.D. only)
6 Cooler hose (HI)
7 Cooler hose (LO)
CONTROL SYSTEM
A
A
B
B
5
4
3
1
2
6
TO
FUEL PIPE
8.9—12.7
{90—130, 79—112}
N·m {kgf·cm, in·lbf}
8.9—12.7
{90—130, 79—112}
A6E85402004
1 Connector
2 Heater hose No.1
3 Heater hose No.34 Water heater unit
5 Fuel pump (water heater system)
6 Exhaust pipe

U–16
CONTROL SYSTEM
FUEL PUMP (WATER HEATER SYSTEM) INSPECTIONA6E8540133502011. Inspect for continuity between fuel pump terminal
A and B using an ohmmeter.
•If not as specified, replace the fuel pump
(water heater system).
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CLIMATE CONTROL UNIT INSPECTIONA6E854061190201Full-auto Air Conditioner
1. Connect the all center panel connectors.
2. Turn the ignition switch to ON position.
3. Measure the voltage at each climate control unit terminal and refer to the terminal voltage list.
•If not as specified, inspect the parts listed under “Action” and the related wiring harness.
—If there is any malfunction, replace the climate control unit.
Terminal Voltage List (Reference)
AME8540W007
Terminal Signal Connected to Test condition Voltage (V) Action
1A Blower motor
feedback signal•Blower motor
•Power MOS
FETFan switch is OFF 12 1. Inspect for continuity or
short circuit (Climate control
unit—blower motor: 1A—B)
(Climate control unit—power
MOS FET: 1A—B, 1C—E)
(Blower motor—blower
relay: A—C) (Blower relay—
fuse: D—BLOWER 40 A
fuse)
2. Inspect for continuity (Power
MOS FET—ground: A—
GND) (Blower relay—
ground: A—GND)
3. Inspect power MOS FET
4. Inspect blower motor
5. Inspect blower relay
6. Inspect BLOWER 40 A fuse
7. Replace power MOS FET Fan switch is at manual
LO7.8
Fan switch is at manual
HI
0.2
2A
1W
2B 2C
2D 2E
2F 2G
2H 2I 2K
2L
* 1A
1B
* *
* *
* 1X1C 1E
1F * 1I
1K
1M 1O
1P 1Q 1S
1T 1U
1J 1L
A6E85402001