D FAULT ISOLATION MANUAL

**ON A/C ALL

TASK 21−60−00−810−883
ECS Unable to Cool Cabin and/or Flight Deck − Fault Isolation
1. General
A. This fault isolation procedure is for when the flight crew reports that the cabin or flight
compartment temperature is too high.
B. Refer to the fault tree for the overview of the task.
Refer to FIG 201

2. Job Set−Up Information

Subtask 21−60−00−946−100

A. Reference Information

REFERENCE DESIGNATION
AMM 21−25−06−160−801 Cleaning of the Temperature Sensor
AMM 21−51−01−000−801 Removal of the Dual Heat Exchanger
AMM 21−51−01−400−801 Installation of the Dual Heat Exchanger
AMM 21−51−21−000−801 Removal of the Air Cycle Machine
AMM 21−51−21−400−801 Installation of the Air Cycle Machine
AMM 21−51−31−000−801 Removal of the Pack Bypass Valve
AMM 21−51−31−400−801 Installation of the Pack Bypass Valve
AMM 21−51−41−000−801 Removal of the Turbine Shutoff Valve
AMM 21−51−41−000−802 Removal of the Turbine Shutoff Valve Filter
AMM 21−51−41−400−801 Installation of the Turbine Shutoff Valve
AMM 21−51−41−400−802 Installation of the Turbine Shutoff Valve Filter
Removal of the Pack Flow Control and Shut−off
AMM 21−52−01−000−801
Valve
Removal of the Pack Flow Control and Shut−off
AMM 21−52−01−000−802
Valve Filter
Installation of the Pack Flow Control and Shut−off
AMM 21−52−01−400−801
Valve
Installation of the Pack Flow Control and Shut−off
AMM 21−52−01−400−802
Valve Filter
AMM 21−61−00−710−803 Operational Test of the ECS Temperature Control
AMM 21−61−09−160−802 Cleaning the Cabin Zone Temperature Sensor
AMM 24−00−00−910−801 Electrical/Electronic Safety Precautions
Retrieval of Data from the Central Diagnostic System
AMM 45−00−21−742−801
(CDS) − Environmental Control System (ECS)

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 D FAULT ISOLATION MANUAL

REFERENCE DESIGNATION
Erase Data from the Central Diagnostic System
AMM 45−00−21−743−801
(CDS) − Environmental Control System (ECS)
AMM 49−00−00−869−801 Start Procedure of the APU
AMM 71−00−00−868−801 Engine Start
Air Conditioning Panel Assembly, Non APU & APU
CMM 21−61−21
Option
FIM 21−60−00 Temperature Control
FIM 21−60−00−810−809 PACK FCV (Status) − Fault Isolation
FIM 21−60−00−810−841 FD ACM (Status) − Fault Isolation
FIM 21−60−00−810−842 CAB ACM (Status) − Fault Isolation
FIM 21−60−00−810−846 SEC HX PERF (Status) − Fault Isolation
WM 21−61−00 Temperature Control and Indication System

3. Job Set−Up
Subtask 21−60−00−910−006

A. Obey all the electrical/electronic safety precautions (Refer to AMM 24−00−00−910−801)

B. Before you do the fault confirmation ensure the following circuit breakers are engaged
(1) ECS/BA CONT L AUTO B7 LEFT MAIN
(2) ECS/BA CONT L MAN Q6 RIGHT MAIN
(3) ECS/BA CONT R AUTO R6 RIGHT MAIN
(4) ECS/BA CONT R MAN C7 LEFT MAIN

4. Fault Confirmation
Subtask 21−60−00−810−184

A. Confirm the fault as follows:

(1) Do the retrieval of the Central Diagnostic System (CDS) fault indications and the
Environmental Control System (ECS) Flight Data page 6/7 (Refer to AMM
45−00−21−742−801).
(2) Record the present and historical faults in the applicable maintenance log book. Include the
elapse time for historical faults.
(3) If the fault code in the present faults or fault history is 3001 − PACK FCV, do the fault
isolation for PACK FCV (Refer to FIM 21−60−00−810−809).
(4) If the fault code in the present faults or fault history is 3004 − PACK FCV, do the fault
isolation for PACK FCV (Refer to FIM 21−60−00−810−809).

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 D FAULT ISOLATION MANUAL

(5) If the fault code in the present faults or fault history is 3502 SEC HX PERF, do the fault
isolation for the SEC HX PERF (Refer to FIM 21−60−00−810−846).
(6) If the fault code in the present faults or fault history is 3F01 FD ACM, do the fault isolation
for the FD ACM (Refer to FIM 21−60−00−810−841).
(7) If the fault code in the present faults or fault history is 3F02 CAB ACM, do the fault isolation
for the CAB ACM (Refer to FIM 21−60−00−810−842).
(8) Is the cabin hot and the flight crew operates with the flight compartment vents closed?
(Refer to DH8400−SL 21002A).
NOTE: During the winter season, the combination of low Outside Air Temperature (OAT)
and the flight compartment vent valves in the closed condition can cause a hot
cabin. The ECS Electronic Control Unit (ECU) senses the low temperatures in
the flight compartment with the zone temperature sensor. This commands the
flight compartment pack bypass valve to add heat. The additional heat cannot be
supplied to the flight compartment through closed vents. Thus it is supplied to the
cabin.
(9) If the CDS does not show the fault codes in present faults or fault history, then do the fault
isolation.
(10) Erase the data from the CDS (Refer to AMM 45−00−21−743−801).

5. Fault Isolation
Subtask 21−60−00−810−185

A. Isolate the fault as follows:

Refer to FIG 202, FIG 203 and FIG 204
(1) On the AIR CONDITIONING control panel, set the RECIRC fan on, BLEED 1 and 2 to off. Is
there air flow from all the flight compartment and all the cabin gaspers?
(a) If no, look for a duct that is disconnected either below the cabin floor or in the ECS
bay.
(b) If yes, continue the troubleshooting.
(2) Start the Auxiliary Power unit (APU) (Refer to AMM 49−00−00−869−801).
(3) On the APU control panel, set the BL AIR on.
(4) On the AIR CONDITIONING control panel, set the controls to the positions that follow:
(a) Set the left and right PACK switches to the MAN position.
(b) Set the FLT COMP and CABIN temperature selectors to the full COOL position.
(5) Do a check for air leaks in the ECS bay area.
(a) If there are leaks, repair the leak. Do the Close Out.
(6) Get access to the CDS ECS flight data page 6/7.
(7) Record the four−digit hexagonal code adjacent to the T4S parameter label in the left column
of the ECS flight data page 6/7.

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 D FAULT ISOLATION MANUAL

(8) If the four−digit hexagonal code is not 6400, do the Close−Out.

(9) Use a mirror to do a visual inspection of the Pack Flow Control and Shut−off Valve
(PFCSOV). Make sure that the PFCSOV is fully open. Refer to FIG 202
(10) If the PFCSOV is not fully open, do as follows:
(a) Replace the PFCSOV filter (Refer to AMM 21−52−01−000−802 and AMM
21−52−01−400−802).
(b) Make sure that the packs are on with the APU bleed pressure.
(c) Record the four−digit hexagonal code adjacent to the T4S parameter label in the left
column of the ECS flight data page 6/7.
(d) If the four−digit hexagonal code is not 6400, do the Close−Out.
(e) If the four−digit hexagonal code is 6400 and the PFCSOV is not fully open, replace the
PFCSOV (Refer to AMM 21−52−01−000−801 and AMM 21−52−01−400−801).
(f) If the PFCSOV still does not function, do a check of the wiring between the PFCSOV
and the ECS ECU (Refer to WM 21−61−00):

2100−P23 2100−P3
(PFCSOV) (ECU)
A 41
B 40

2100−P23 2100−P5
(PFCSOV) (ECU)
C 59

(g) If the wiring is unserviceable, repair the wiring. Do the Close Out.
WARNING: EXHAUST FROM THE PACKS WILL BE HOT. MAKE SURE YOU WEAR
PROTECTIVE EQUIPMENT (GLOVES, SAFETY GLASSES, HEARING
PROTECTION). BE CAREFUL WHEN YOU ARE ON THE LADDER. THIS WILL
PREVENT INJURY TO THE MAINTENANCE PERSONNEL AND/OR DAMAGE
TO THE EQUIPMENT.
(11) If the fault continues, feel for the Air Cycle Machine (ACM) exhaust flow from the external
exhaust vents at the top left and right empennage. If necessary, use the ladder.
(12) If there is air flow from both the packs, continue to step 5.A.11.
(13) If there is no flow from both the packs, make sure that the turbine shutoff valve is open on
the pack without flow. Refer to FIG 203
(a) If the turbine shutoff valve is closed, replace the turbine shutoff valve filter (Refer to
AMM 21−51−41−000−802 and AMM 21−51−41−400−802).
(b) If the turbine shutoff valve stays closed, replace the turbine shutoff valve (Refer to
AMM 21−51−41−000−801 and AMM 21−51−41−400−801).

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 D FAULT ISOLATION MANUAL

(c) If the turbine shutoff valve stays closed, do a check of the wiring between the left pack
turbine shutoff valve and the ECS ECU (Refer to WM 21−61−00):

2100−P15 2100−P2
(Left Pack Turbine Shutoff Valve) (ECU)
A 31
B 3

(d) If the wiring is unserviceable, repair the wiring. Do the Close Out.
(e) If the turbine shutoff valve still stays closed, do a check of the wiring between the right
pack turbine shutoff valve and the ECS ECU (Refer to WM 21−61−00):

2100−P17 2100−P5
(Right Pack Turbine Shutoff Valve) (ECU)
A 66
B 49

(f) If the wiring is unserviceable, repair the wiring. Do the Close Out.
(g) If the turbine shutoff valve is open, replace the ACM (Refer to AMM
21−51−21−000−801 and AMM 21−51−21−400−801).
(14) If the fault continues, make sure that the pack bypass valves are closed.
NOTE: The valves can be slightly open to prevent the ice formation, but must not be fully
open.
(15) If one of the pack bypass valve is open, replace the pack bypass valve that stays open
(Refer to AMM 21−51−31−000−801 and AMM 21−51−31−400−801). Refer to FIG 204
(16) If the steps 5.A.6 through 5.A.12 have been performed with the APU bleed air and the
system is cooling correctly, repeat the steps 5.A.6 through 5.A.12 with the engine bleed air
(Refer to AMM 71−00−00−868−801).
NOTE: APU bleed air supplies considerable more flow and pressure than the engine
bleed air. This additional pressure will mask the marginal valve performance.
(17) If the fault continues, do a check of the flight compartment temperature sensor and the
cabin zone temperature sensor for contamination as follows:
(a) If there is contamination on the flight compartment sensor and the cabin zone
temperature sensor, clean the sensors (Refer to AMM 21−25−06−160−801 and AMM
21−61−09−160−802). Do the Close Out.
(18) If the fault continues, do a resistance check of the CABIN temperature control potentiometer
(2164−R4) and the FLT COMP temperature control potentiometer (2161−R1) (Refer to
CMM 21−61−21):
(a) If the potentiometers do not function correctly, replace the unserviceable
potentiometer. Do the Close Out.
(19) If the fault continues, get access to the heat exchanger top surface.

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 D FAULT ISOLATION MANUAL

(20) If there are holes, leakage or contamination in the heat exchanger, replace the heat
exchanger (Refer to AMM 21−51−01−000−801 and AMM 21−51−01−400−801).

6. Close Out
Subtask 21−60−00−710−002

A. Do the operational test of the ECS temperature control (Refer to AMM 21−61−00−710−803).

Subtask 21−60−00−941−097

B. Do the CDS fault message retrieval for the ECS (Refer to AMM 45−00−21−742−801).
C. Make sure that the ECS fault codes retrieved in the step 4.A. are not shown in the ECS present
fault page.

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 D FAULT ISOLATION MANUAL

Do the retrieval of the Central Diagnostic

System (CDS) fault indications for the
Environmental Control System (ECS) (Refer
to AMM 45−00−21−742−801).
Record the present and historical fault codes.

If the fault code is 3502−SEC HX PERF, do the

fault isolation for the SEC HX PERF (Refer to
FIM 21−60−00−810−846).
Are Fault Codes YES If the fault code is 3F01−FD ACM, do the fault
3502, 3F01 and 3F02 isolation for the FD ACM (Refer to FIM
present? 21−60−00−810−841).
If the fault code is 3F02−CAB ACM, do the fault
isolation for the CAB ACM (Refer to FIM
21−60−00−810−842).
NO
Erase the data from the CDS (Refer to
AMM 45−00−21−743−801).

On the AIR CONDITIONING control

panel, set the RECIRC fan on, BLEED 1
and 2 to off.

Make sure that the flight compartment

lower vents and gaspers are open.
(Refer NOTE 1).

NOTE 1: (Refer to SL DH8400−SL 21002A). During the winter season, the low Outside Air
Temperature (OAT) and the flight compartment vent valves in closed condition can cause a hot
cabin. The ECS Electronic Control Unit (ECU) senses the low temperatures in the flight
compartment with the zone temperature sensor. This commands the flight compartment pack
bypass valve to add heat. The additional heat cannot be supplied to the flight compartment
through the closed vents. Thus it is supplied to the cabin.

Is there air flow from NO Rectify the duct that has separated,
all the flight compartment either below the cabin floor or in the A
and the cabin gaspers? ECS bay.
cg3229a01.dg, sg, may14/2014

YES

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 1 of 7)

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 D FAULT ISOLATION MANUAL

Start the Auxiliary Power Unit (APU) (Refer to AMM 49−00−00−869−801). On the APU control
panel, set the BL AIR on. On the AIR CONDITIONING control panel, set the left and right PACK
switches to the MAN postion. Set the FLT COMP AND CABIN temperature selectors to the
full COOL position.

Are there leaks YES

in the ECS bay? Repair the leaks. A

NO
Use a mirror to do a visual inspection of the
Pack Flow Control and Shut−Off Valve (PFCSOV).
Make sure that the PFCSOV is open (approximately
50% or more).

NO Replace the PFCSOV filter (Refer

Is the PFCSOV open? to AMM 21−52−01−000−802 and
AMM 21−52−01−400−802).

YES
YES
Is the PFCSOV open?

NO

Replace the PFCSOV (Refer to

cg3231a02.dg, sg, may16/2014

AMM 21−52−01−000−801 and

AMM 21−52−01−400−801).

C D

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 2 of 7)

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 D FAULT ISOLATION MANUAL

C D

YES
Is the PFCSOV open?

NO
Do a check of the wiring between the
PFCSOV and the ECS ECU (Refer to
WM 21−61−00).

YES
Is the wiring serviceable?

NO
Feel for the Air Cycle Machine (ACM) exhaust Repair the wiring. A
flow from the external exhaust vents at the
top left and right empennage. If necessary,
use the ladder.
Caution: Hot Air Blast.

Is hot air exiting from YES Verify the pack bypass

the exhaust vents? E
valve operation.
cg3229a03.dg, sg, may14/2014

NO

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 3 of 7)

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 D FAULT ISOLATION MANUAL

Are the two turbine YES Replace the applicable turbine shutoff valve
shutoff valves closed? filter (Refer to AMM 21−51−41−000−802
and AMM 21−51−41−400−802).

NO
NO Does the turbine
shutoff valve stay
closed?

YES
Replace the applicable turbine shutoff valve
(Refer to AMM 21−51−41−000−801
and AMM 21−51−41−400−801).

NO
Does the turbine shutoff
valve stay closed?

YES
Do a check of the wiring between the turbine
shutoff valve and the ECS ECU (Refer to
WM 21−61−00).

YES
Is the wiring serviceable?
cg3229a04.dg, sg, may14/2014

NO

G H

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 4 of 7)

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 D FAULT ISOLATION MANUAL

G H

Repair the wiring. A

NO Replace the ACM (Refer to AMM

Does the ACM function
with the turbine shutoff 21−51−21−000−801 and AMM A
valve open? 21−51−21−400−801).

YES

Are the pack bypass NO Replace the applicable pack bypass valve
valves closed? (Refer to AMM 21−51−31−000−801 and A
(Refer NOTE 2). AMM 21−51−31−400−801).

NOTE 2: Valves can be slightly open to

prevent the ice formation.
YES
Repeat the procedure using the engine bleed air (Refer to AMM 71−00−00−868−801).
NOTE 3: APU bleed air supplies considerable more flow and pressure than the engine bleed air.
This additional pressure will mask the marginal valve performance.

NO
Does the fault continue? A
cg3229a05.dg, sg, may14/2014

YES

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 5 of 7)

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 D FAULT ISOLATION MANUAL

Do a check of the flight

compartment temperature sensor
and the cabin zone temperature
sensor for contamination.

Are the flight

Clean the flight compartment and
compartment and YES cabin temperature sensors (Refer
cabin zone temperature A
to AMM 21−25−06−160−801
sensors contaminated?
and AMM 21−61−09−160−802).

NO

Do a resistance check of the CABIN temperature control switch (2164−R4) and the
FLT COMP temperature control switch (2161−R1) (Refer to CMM 21−61−21).

NO Replace the applicable

Do the potentiometers A
potentiometer.
function correctly?

YES

Get access to the heat

exchanger top surface.
cg3229a06.dg, sg/ps, apr13/2015

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 6 of 7)

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 D FAULT ISOLATION MANUAL

Does the heat

exchanger show signs of YES Replace the heat exchanger (Refer to
AMM 21−51−01−000−801 and A
cracking, holes, leakage
AMM 21−51−01−400−801).
or contamination?

NO

Do the operational test of the ECS

temperature control (Refer to AMM
21−61−00−710−803).

Do the CDS fault message retrieval

for the ECS (Refer to AMM
45−00−21−742−801).

YES Do the fault isolation for the

Are fault codes present? CDS present fault codes (Refer
to FIM 21−60−00).

NO
Close Out
cg3229a07.dg, sg, may14/2014

UNABLE TO COOL CABIN AND/OR FLIGHT DECK − FAULT ISOLATION

Figure 214 (Sheet 7 of 7)

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 D FAULT ISOLATION MANUAL

LOCKOUT ARM
SHOWN IN OPEN
POSITION. ROTATE
CCW TO CLOSE

CLOSED
POSITION
cg3244a01.dg, rc, apr22/2014

SWITCH

Pack Flow Control and Shut Off Valve

Figure 215

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 D FAULT ISOLATION MANUAL

LOCKOUT ARM
cg3245a01.dg, rc, apr22/2014

SHOWN IN CLOSED
POSITION. ROTATE
CCW TO OPEN

Turbine Shut Off Valve

Figure 216

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 D FAULT ISOLATION MANUAL

VIEW LOOKING FORWARD

cg3246a01.dg, rc, apr22/2014

VALVE SHOWN
IN CLOSED
POSITION. ROTATE
CCW TO OPEN

Pack Bypass valve

Figure 217

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