Land Rover Discovery Lhd Models Etm 1995 4th Edition Exp Rover Manual

							COMPRESSOR CONTROLS
1
ETM K2
DISCOVERY
ELECTRICAL TROUBLESHOOTING MANUAL
CIRCUIT OPERATION
Compressor Control (MFI±V8) (300Tdi with EDC)
With the Ignition Switch (X134) in position II,
battery voltage is applied to the Ignition Load Relay
(K127). The relay is energized, applying battery
voltage to the Compressor Clutch Relay (K108)
and the A/C Logic Relay (K170). When the Front
Fan Speed Switch (X247) is turned to positions I,
II, III, or IV and the Front A/C Switch (X225) is
turned On, ground is provided to terminal 86 of the
A/C Logic Relay (K170) through the closed
contacts of the A/C Dual Pressure Switch (X102)
and the Front A/C Evaporator Temperature Switch
(X101).
The relay is energized, applying battery voltage to
the Engine Control Module (ECM) (Z132),
signalling the ECM that compressor operation has
been requested. The ECM then provides ground to
the coil of the Compressor Clutch Relay (K108).
The relay is energized, applying battery voltage to
the Compressor Clutch (K107). Compressor Clutch
operation is now controlled by the status of the A/C
Dual Pressure Switch (X102) and the Front A/C
Evaporator Temperature Switch (X101).
The Front A/C Evaporator Temperature Switch
(X101) is fitted in the airflow out of the front
evaporator to sense the temperaure of the exterior
fins. Should ice begin to form, due to low
temperature, the switch will open. The A/C Dual
Pressure Switch (X102) monitors refrigerant
pressure in the high pressure line, should pressure
become too high or too low the switch will open.
When one or both of these switches open the
ground supply to terminal 86 of the A/C Logic
Relay (K170) will be interrupted. The relay
de±energizes, removing battery voltage from the
Engine Control Module (ECM) (Z132), signalling
the ECM that compressor operation should be
turned off. The ECM removes the ground supply to
the coil of the Compressor Clutch Relay (K108).
The relay then de±energizes, removing battery
voltage from the Compressor Clutch (K107),
disengaging the Compressor.
Compressor Control (MFI±T16)
With the Ignition Switch (X134) in position II,
battery voltage is applied to the Compressor Clutch
Relay (K108) and the A/C Logic Relay (K170).
When the Front Fan Speed Switch (X247) is turnedto positions I, II, III, or IV and the Front A/C Switch
(X225) is turned On, ground is provided to terminal
85 of the A/C Logic Realy (K170) through the
closed contacts of the A/C Dual Pressure Switch
(X102) and the Front A/C Evaporator Temperature
Switch (X101).
The relay is energized, applying ground to terminal
35 of the Engine Control Module (ECM) (Z132),
signalling the ECM that compressor operation has
been requested. The ECM then provides ground to
the terminal 85 of the Compressor Clutch Relay
(K108). The relay is energized, applying battery
voltage to the Compressor Clutch (K107).
Compressor Clutch operation is now controlled by
the status of the A/C Dual Pressure Switch (X102)
and the Front A/C Evaporator Temperature Switch
(X101).
The Front A/C Evaporator Temperature Switch
(X101) is fitted in the airflow out of the front
evaporator to sense the temperaure of the exterior
fins. Should ice begin to form, due to low
temperature, the switch will open. The A/C Dual
Pressure Switch (X102) monitors refrigerant
pressure in the high pressure line, should pressure
become too high or too low the switch will open.
When one or both of these switches open, the
ground supply to terminal 85 of the A/C Logic
Relay (K170) will be interrupted. The relay
de±energizes, removing the ground supply from
terminal 35 of the Engine Control Module (ECM)
(Z132), signalling the ECM that compressor
operation should be turned off. The ECM removes
the ground supply to terminal 86 of the Compressor
Clutch Relay (K108). The relay then de±energizes,
removing battery voltage from the Compressor
Clutch (K107), disengaging the Compressor. 
						

							COMPRESSOR CONTROLS
2
K2 ETM
DISCOVERY
ELECTRICAL TROUBLESHOOTING MANUA L
Compressor Control (300Tdi without EDC)
With the Ignition Switch (X134) in position II,
battery voltage is applied to the Ignition Load Relay
(K127). The relay is energized, applying battery
voltage to the Compressor Clutch Relay (K108).
When the Front Fan Speed Switch (X247) is turned
to positions I, II, III, or IV and the Front A/C Switch
(X225) is turned On, ground is provided to terminal
86 of the Compressor Clutch Relay (K108) through
the closed contacts of the A/C Dual Pressure
Switch (X102), the Front A/C Evaporator
Temperature Switch (X101), and the Compressor
Clutch Cut±out Switch (X259).
The relay is energized, applying battery voltage to
the Compressor Clutch (K107). Compressor Clutch
operation is now controlled by the status of the A/C
Dual Pressure Switch (X102), the Front A/C
Evaporator Temperature Switch (X101), and the
Compressor Clutch Cut±out Switch (X259).
The Front A/C Evaporator Temperature Switch
(X101) is fitted in the airflow out of the front
evaporator to sense the temperaure of the exterior
fins. Should ice begin to form, due to low
temperature, the switch will open. The A/C Dual
Pressure Switch (X102) monitors refrigerant
pressure in the high pressure line, should pressure
become too high or too low the switch will open.
When one or more of these switches open, the
ground supply to terminal 86 of the Compressor
Clutch Relay (K108) will be interrupted. The relay
de±energizes, removing battery voltage from the
Compressor Clutch (K107), disengaging the
Compressor.
Rear A/C Refrigerant Control Valve
When front A/C has been selected and the
Compressor Clutch (K107) is engaged, the
Compressor Clutch Relay (K108) is energised and
voltage is applied on the BG wires to the Rear A/C
Refrigerant Control Valve (K207).  When rear A/C
is selected a ground signal is applied to the Rear
A/C Switch Amplifier (Z216).  The Rear A/C Switch
Amplifier (Z216) then applies a ground signal to
energise the Rear A/C Control Relay (K194
) and
the Rear A/C Fan Speed Relay (K205).  When the
Passengers Rear Fan Speed Switch (X246) is in
any position other than Off, ground is applied to the
Rear A/C Refrigerant Control Valve (K207) through
the closed contacts of the Passengers Rear Fan
Speed Switch (X246), BR wire, closed contacts ofthe Rear A/C Fan Speed Relay (K205), PG wire,
UB wire, Rear A/C Refrigerant Control Valve Diode
(Z228), P wire, closed contacts of the Rear A/C
Evaporator Temperature Switch (X260), and the
RG wire.
The Rear A/C Evaporator Temperature Switch
(X260) senses the temperature of the exterior fins.
Should ice begin to form due to low temperature,
the switch will open and the ground supply to the
Rear A/C Refrigerant Control Valve (K207) will then
be interrupted.  The valve de±energises and
refrigerant flow is interrupted.
The Rear A/C Refrigerant Control Valve (K207) will
also be de±energised if one or more of the
following conditions occurs:

The Front A/C Switch (X225) has been turned
OFF.

The Front Fan Speed Switch (X247) has been
turned OFF.

The Rear A/C switches have been turned OFF.

The Passengers Rear Fan Speed Switch
(X246) has been turned OFF.

The ECM determines that compressor clutch
operation is no longer required.

Compressor Clutch (K107) operation has been
disabled by the A/C Dual Pressure Switch
(X102) or the Front A/C Evaporator
Temperature Switch (X101).

Compressor Clutch (K107) operation has been
disabled by the Compressor Clutch Cut±Out
Switch (X259) (300Tdi Without EDC Only). 
						

							ELECTRICAL TROUBLESHOOTING MANUAL
ETM K2
Compressor Controls
3
DISCOVERY
S2045
15
F 15
10 A
9 C204
E200
See Fuse Details
A
K2-8
P126
Fascia Fuse Box
0.5 LGP
85
30
C2007K127
Ignition Load
Relay
S227 2.0 WG87
B
K2-4
Z211
Fan Timer Diode
0.5 GW1.0 WG 2.0 WG
7 C2073
1.25 UR 0.5 WG
Cooling Fans
See Ground Dis-
tribution
See Fuse Details
30 C2007
15
F 6
25 AP127
Satellite Fuse
Box 1
85
86 87
86
0.5 B
K2-5MFI±V8
MFI±T16
S2015
K2-6 300Tdi without
EDC
K2-7 300Tdi with EDC
K2-10
C
1.0 WG13 C212
0.5 WG
HJ10 
						

							ELECTRICAL TROUBLESHOOTING MANUA L
K2 ETM
Compressor Controls (MFI±V8)
4
DISCOVERY
S296
30
F 3
30 A
E100
See Fuse Details
16 C217
30 1.0 NG
[2] 30
87
86
85
86 C241
1.0 BG
85 C241 87
0.5 BS
33 C24321
30
30
87
85
86
85 C242
86 C242 87
1.0 WG
18 C217
B
K2-3
0.5 YB
11 C217
0.5 YB
9 C2073
0.5 U
0.5 OG
1 C2076 K108
Compressor
Clutch RelayK170
A/C Logic Relay
X101
Front A/C Evap-
orator Tempera-
ture Switch
[1] > 0
C (32
F)
[2] < 0
C (32
F) Z132
Engine Control
Module (ECM)
1 C2077
8 C2073
0.5 ON S295
1 C145
2 C145B
1.0 B
K107
Compressor
Clutch
See Ground Dis-
tribution 1C116
0.5
GY
P125
Engine Compart-
ment Fuse Box
0.5 WG
D
K2-9 6 C216
0.5 BG
[1]
K2-8
E 
						

							ELECTRICAL TROUBLESHOOTING MANUAL
ETM K2
Compressor Controls (MFI±T16)
5
DISCOVERY
30
F 3
30 A
E103
See Fuse Details
16 C217
30 1.0 NG
[2] 30
87
85
86
85 C241
1.0 BG
86 C241 87
0.5 BS
19 C1007
30
30
87
86
85
86 C242
85 C242 87
0.5 YB
11 C217
0.5 YB
9 C2073
0.5 U
0.5 OG
1 C2076 K108
Compressor
Clutch RelayK170
A/C Logic Relay
Z132
Engine Control
Module (ECM)
1 C2077
8 C2073
0.5 ON S295
1 C145
2 C145B
1.0 B
K107
Compressor
Clutch
See Ground Dis-
tribution 1C116
P125
Engine Compart-
ment Fuse Box
0.5 BN
D
K2-9 6 C216
0.5 BG 1.0
WG
Z132
Engine Control
Module (ECM)
35 C1007
0.5 B
E103
See Ground Dis-
tribution
15
F 3
10 A
See Fuse DetailsP127
Satellite Fuse
Box 1
S2034
0.5 WG
B
K2-3
1.0 WG
18 C217
Not used
[1]
K2-8
E
X101
Front A/C Evap-
orator Tempera-
ture Switch
[1] > 0
C (32
F)
[2] < 0
C (32
F) 
						

							C2073
ELECTRICAL TROUBLESHOOTING MANUA L
K2 ETM
Compressor Controls (300Tdi without EDC)
6
DISCOVERY
S295
30
F 3
30 A
1C116
E103
See Fuse DetailsP125
Engine Compart-
ment Fuse Box
1.0 NG
30
30
86 C241
0.5 G
11 C217
2 C162
K108
Compressor
Clutch Relay
X259
Compressor Clutch
Cut±out Switch
16 C217
See Ground Dis-
tribution
1.0 WG
85 C241
87
87
1.0 BG18 C217
B
K2-3
1 C162
0.5 YB
0.5 YB
9 C2073
0.5 U
1 C2076
X101
Front A/C Evaporator
Temperature Switch
[1] > 0
C (32
F)
[2] < 0
C (32
F)
8
1 C2077
0.5 OG
0.5 ON
1 C145
K107
Compressor
Clutch
0[1]
[2]
2 C145
B
1.0 B
85
86
D
K2-9
0.5 BG6 C216
0.5 WG
[1]
K2-8
E 
						

							ELECTRICAL TROUBLESHOOTING MANUAL
ETM K2
Compressor Controls (300Tdi with EDC)
7
DISCOVERY
S2060
30
F 3
30 A
E103
See Fuse Details
16 C217
30 1.0 NG
[2] 30
87
85
86
85 C241
1.0 BG
86 C241 87
0.5 BS
9 C24344
87
87
30
85
86
85 C242
86 C242 30
1.0 WG
18 C217
B
K2-3
1.0 YB
11 C217
0.5 YB
9 C2073
0.5 U
0.5 OG
1 C2076 K108
Compressor
Clutch RelayK170
A/C Logic Relay
X101
Front A/C Evap-
orator Tempera-
ture Switch
[1] > 0
C (32
F)
[2] < 0
C (32
F) Z132
Engine Control
Module (ECM)
1 C2077
8 C2073
0.5 ON S295
1 C145
2 C145B
1.0 B
K107
Compressor
Clutch
See Ground Dis-
tribution 1C116
0.5
YG
P125
Engine Compart-
ment Fuse Box
0.5 WG
D
K2-9 6 C216
0.5 BG
S296
1.0 BG0.7 BG
[1]
K2-8
E 
						

							ELECTRICAL TROUBLESHOOTING MANUA L
K2 ETM
Compressor Controls
8
DISCOVERY
52 C2025
10 C2067
2 C2022 2 C2067
See Ground Dis-
tribution
S263
1.0 UR
0.5 URBlower Controls
Interior Lamps
0.5 LG
0
13 C2025
0.5 WB
S244
E200
0.5
N
Blower ControlsS2056
2.0 N
See Ground Dis-
tribution
E200
1 C2022
0III
III
IV
4 C2073
Cooling Fans
19 C217 0.5 PB
1 C181
X102
A/C Dual Pressure
Switch
[1] > 32 Bar (455 psi)
[2] < 2.07 Bar (30 psi) 0.5 ON
2 C181MFI±T16 MFI±V8
[1] [2]
Z210
Condenser Fan
Control Diode 2
X247
Front Fan Speed
SwitchX225
Front A/C Switch
K2-5 K2-4
0.5 YB
0.5 NW
4
1.0 N
0.5 N
0.5 N
2 C2027
0.5
PB300Tdi without
EDC K2-6
300Tdi with EDC K2-7
1 C2067
1.0 NW
S2071
[1]
S2038 1.25 URK2-3
A
E 
						

							ELECTRICAL TROUBLESHOOTING MANUAL
ETM K2
Compressor Controls
9
DISCOVERY
0
8 C212
0.5 BG
D
MFI±T16 MFI±V8
K2-5 K2-4
300Tdi without EDC K2-6
300Tdi with EDC K2-7
1.0 BG
3 C448
1.25 BG
1 C464
K207
Rear A/C
Refrigerant Con-
trol Valve
2 C464
0.5 RG
1 C460
X260
Rear A/C Evapor-
ator Temperature
Switch
1 C461
0.5 P
9 C448
Z228
Rear A/C
Refrigerant Con-
trol Valve Diode
0.5 UB
12 C448
K205
Rear A/C Fan
Speed Relay
2 C466
30
87
4 C466
K193
Rear Blower
Motor Relay
3 C45785
5 C391
0III
III
IV
X246
Passengers Rear
Fan Speed
Switch
E400
1 C391
3.0 B
S417
0.5 BR
6 C448 0.5 PG
S428
See Ground Dis-
tribution
0.5 PG
[1] 
						

							COMPRESSOR CONTROLS
10
K2 ETM
DISCOVERY
ELECTRICAL TROUBLESHOOTING MANUA L
TROUBLESHOOTING HINTS
9. If the Blower Motor(s) do not operate normally,
refer to Blower Controls, Section K1.
10. Check Fuse F3 of the Engine Compartment
Fuse Box (P125), F3 of the Satellite Fuse Box,
and Fuse F15 of the Fascia Fuse Box (P126).
11. Verify that refrigerant pressure is OK before
preceeding with the following diagnostic text.
SYSTEM DIAGNOSIS (MFI±V8)
1. If the A/C Compressor Clutch (K107) does not
engage in any mode, do Test A.
2. If the Compressor Clutch (K107) remains
engaged with the A/C off, do Test F.
SYSTEM DIAGNOSIS (MFI±T16)
1. If the A/C Compressor Clutch (K107) does not
engage in any mode, do Test B.
2. If the Compressor Clutch (K107) remains
engaged with the A/C off, do Test G.
SYSTEM DIAGNOSIS (300TDI WITHOUT EDC)
1. If the A/C Compressor Clutch (K107) does not
engage in any mode, do Test C.
2. If the Compressor Clutch (K107) remains
engaged with the A/C off, do Test H.
SYSTEM DIAGNOSIS (300TDI WITH EDC)
1. If the A/C Compressor Clutch (K107) does not
engage in any mode, do Test D.
2. If the Compressor Clutch (K107) remains
engaged with the A/C off, do Test I.