1991 ACURA NSX air condition

Air Cleaner (ACL)

ACL Element Replacement

ACL HOUSING

COVER

ACL ELEMENT

Normal conditions:

Replace air cleaner element every

30,000 miles (48,000 km) or 24

months whichever comes first.

Severe conditions:

Clean air cleaner element every

15,000 miles (24,000 km) or 12

months and replace every 30,000

miles (48,000 km) or 24 months

whichever comes first.

ACL HOUSING

RESONATOR

INTAKE

AIR DUCTProCarManuals.com

Troubleshooting Precautions

EPS Indicator Light

Under normal conditions, the EPS indicator light in the gauge assembly comes on when the ignition switch is turned to

the ON (II) position, then goes off after the engine is started. This indicates that the bulb and its circuits are operating cor-

rectly. If there is any trouble in the system, the EPS indicator light turns on during driving, and the power steering assist is

turned off. When the EPS indicator light comes on, the control unit memorizes the DTC. In this case, the control unit does

not activate the EPS system after the engine starts again but it keeps the EPS indicator light on.

Diagnostic Trouble Code (DTC)

• The lowest DTC is indicated first.

• The DTCs continue blinking until the ignition switch is turned off.

• The DTCs are erased from the control unit when the EPS control unit VBU power supply or connector is disconnected.

• The EPS system can be reset and the control unit's memory can be erased by disconnecting the CLOCK (7.5 A) fuse for

more than ten seconds.

Self-diagnosis:

The CPU (central processing unit) controls the following when it detects a problem during self-diagnosis:

1. Turns the EPS indicator light ON to alert the driver.

2. Power assist stops, and normal manual steering operation resumes (except DTC 21 and DTC 33).

3. The EPS control unit memorizes the diagnostic trouble code (DTC).

4. After the DTC is stored in the control unit, the CPU stops self-diagnosis.

Troubleshooting:

• Before starting the troubleshooting, clear the DTC by disconnecting the CLOCK (7.5 A) fuse for ten seconds or more,

and test-drive the car. Check that the symptom of the trouble appears again, and then troubleshoot. If the problem is an

intermittent problem, the system does not become active after the engine starts even though the problem is solved.

• When both EPS indicator light and A/T "D" indicator light come on, perform the A/T troubleshooting first.

• When the customer's reported problem cannot be verified in the car, ask the customer about the conditions when the

EPS indicator light came ON, then test-drive the car under those conditions, if possible. If the EPS indicator light does

not come ON during the test, check for loose connections or poor contacts at the connectors by wiggling the harness,

etc.

• The connector terminal numbers are viewed from the wire side for the female terminals and from the terminal side for

the male terminals.

• After the repair, test-drive the car and check that the EPS indicator light does not come ON again during the test. (Refer

to the Symptom-to-System Chart for diagnostic period.)ProCarManuals.com

Anti-lock Brake System (ABS) Description

Features/Construction/Operation (cont'd)

ABS Control Unit

The ABS control unit consists of a main function section, which controls the operation of anti-lock brake system, and

sub-function, which controls the pump motor and "self-diagnosis."

1. Main Function

The main function section of the ABS control unit performs calculations on the basis of the signals from each wheel

sensor and controls the operation of the anti-lock brake system by putting into action the solenoid valves in the

modulator unit for each front and rear brake.

2. Sub-Function

The sub-function section gives driving signals to the pump motor and also gives "self-diagnosis" signals, necessary

for backing up the anti-lock brake system.

Self-Diagnostic Function

Since the anti-lock brake system modulates the braking pressure when a wheel is about to lock, regardless of the driver's

intention, the system operation and the braking power will be impaired if there is a malfunction in the system. To prevent

this possibility, at speeds above 6 mph (10 km/h), the self-diagnosis function monitors the main system functions. When

an abnormality is detected, the ABS indicator light comes on.

There is also a check mode of the self-diagnosis system itself: when the ignition switch is first turned on, the ABS in-

dicator light comes on and stays on for a few seconds after the engine starts, to signify that the self-diagnosis system is

functional.

Fail-Safe Function

If an abnormality is detected, the ABS control unit turns off the fail-safe relays and motor relay. In this condition, the

anti-lock brake system is prevented from functioning, yet the basic brake system continues to operate normally.

The ABS Indicator Light Comes On

1. When the fluid pressure pump runs more than 120 seconds.

2. When the parking brake is applied for more than 30 seconds while the vehicle is being driven.

3. When the rear wheel(s) is (are) locked more than a specified time.

4. When the wheel rotation signal is not transmitted due to faulty wire or sensor.

5. When the operation time of the solenoid valve(s) exceeds a predetermined valve, and the ABS control unit finds an

open in the solenoid circuit.

6. When the output signals from both main functions in the ABS control unit are not transmitted to the solenoid

valve(s).ProCarManuals.com

Operation

1. Ordinary Braking Function

In ordinary brake operations, the cut-off out valve in the modulator is open to transmit the hydraulic pressure from

the master cylinder to the brake calipers via the chamber A and the chamber B.

The chamber C is connected to the reservoir through the outlet valve which is normally open. It is also connected to

the hydraulic pressure source (pump, accumulator, pressure switch, etc.) via the inlet valve which is normally

closed. The chamber D serves as an air chamber. Under these conditions, the pressures of the chambers C and D are

maintained at about the atmospheric pressure, permitting regular braking operations.ProCarManuals.com

A/C Servic e Tip s an d Precaution s
The ai r conditionin g syste m use s HFC-134 a (R-134a ) refrigeran t an d polyalkyleneglyco l (PAG ) refrigeran t oi l (ND-OI L
8 : P/ N 38899-PR7-A01) , whic h ar e no t compatibl e wit h CFC-1 2 (R-12 ) refrigeran t an d minera l oil . D o no t us e R-1 2 refriger -
an t o r minera l oi l i n thi s system , an d d o no t attemp t t o us e R-1 2 servicin g equipment ; damag e t o th e ai r conditionin g
system o r you r servicin g equipmen t wil l result .
Only us e servic e equipmen t tha t i s U.L.-liste d an d i s certifie d t o mee t th e requirement s o f SA E J221 0 t o remov e R-134a;
fro m th e ai r conditione r system .
CAUTION : Exposur e to ai r conditione r refrigeran t an d lubrican t vapo r o r mis t ca n irritat e eyes , nos e an d throat , Avoi d
breathin g th e ai r conditione r refrigeran t an d lubrican t vapo r o r mist .
I f accidenta l syste m discharg e occurs , ventilat e wor k are a befor e resumin g service .
R-134 a servic e equipmen t o r vehicl e ai r conditione r system s shoul d no t b e pressur e teste d o r lea k teste d wit h compresse d
air.
Som e mixture s o f ai r an d R-134 a hav e bee n show n to b e combustibl e elevate d pressure s an d ca n resul t
i n fir e o r explosio n causin g injur y o r propert y damage . Neve r us e compresse d ai r t o pressur e tes t R-134 a servic e
equipmen t o r vehicl e ai r conditionin g systems .
Additiona l healt h an d safet y informatio n ma y b e obtaine d fro m th e refrigeran t an d lubrican t manufacturers .
1 . Alway s disconnec t th e negativ e cabl e fro m th e batter y wheneve r replacin g ai r conditionin g parts .
2 . Kee p moistur e an d dus t ou t o f th e system . Whe n disconnectin g an y lines , plu g o r cap the fitting s immediately ; don' t
remov e th e cap s o r plug s unti l jus t befor e yo u reconnec t eac h line .
3 . Befor e connectin g an y hos e o r line , appl y a fe w drop s o f refrigeran t oi l (ND-OI L 8 ) t o th e O-ring .
4. Whe n tightenin g o r loosenin g a fitting , us e a secon d wrenc h t o suppor t th e matchin g fitting .
5. Whe n recoverin g th e system , us e a R-134 a refrigeran t Recovery/Recycling/Chargin g System ; don' t releas e
refrigeran t int o th e atmosphere .
6 . Ad d refrigeran t oi l (ND-OI L 8 ) afte r replacin g th e followin g parts :
NOTE:
• D o no t retur n th e oi l t o th e containe r onc e dispense d an d neve r mi x wit h othe r refrigeran t oil s t o avoi d
contamination .
• Immediatel y afte r usin g th e oil , replac e th e ca p o n th e containe r an d sea l i t t o avoi d moistur e absorption .
• D o no t spil l th e refrigeran t oi l o n th e car ; i t ma y damag e th e paint ; i f th e refrigeran t oi l contact s th e paint , was h i t
of f immediately .
Condenser ........................ . 10 c c (1/ 3 fl oz )
Evaporato r ........................ . 1 0 c c (1/ 3 f l oz )
Lin e o r hos e ....................... . 2 0 c c (2/ 3 f l oz )
Receive r ........................... . 1 0 c c (1/ 3 f l oz )
Compresso r ....................... . O n compresso r
replacement , subtrac t th e volum e o f oi l drain -
e d fro m th e remove d compresso r fro m 14 0 c c
(4-2/ 3 f l oz) , an d drai n th e calculate d volum e
o f oi l fro m th e ne w compressor : 14 0 c c (4-2/ 3
f l oz ) — Volum e o f oi l fro m remove d com -
presso r = Volum e t o drai n fro m ne w com -
pressor .
CORROSIO N RESISTAN T BOL T
Suctio n hos e an d discharg e hos eto A/ C line s ..................... . 2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )Discharg e lin e C(bot h sides ) ..................... . 2 3 N- m (2. 3 kg-m , 1 7 Ib-ft )Condense r lin e A(bot h sides ) ..................... . 2 3 N- m (2. 3 kg-m , 1 7 Ib-ft )Condense r lin e C to lef t sid econdense r ....................... . 1 4 N- m (1. 4 kg-m , 1 0 Ib-ft )Receiver/drye r ................. . 1 4 N- m (1. 4 kg-m , 1 0 Ib-ft )
Receive r lin e an d suctio n lin e t o heate rassembl y ........................ . 2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )Compresso r hos e mountin gbolts .............................. . 2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )Compresso r mountin gbolts .............................. . 2 5 N- m (2. 5 kg-m , 1 8 Ib-ft )Compresso r bracke tmountin g bolt s ................ . 5 0 N- m (4. 5 kg-m , 3 6 Ib-ft )Idler pulle y cente r nu t ....... . 4 5 N- m (4. 5 kg-m , 3 3 Ib-ft )6 m m bol t ................... . 1 0 N- m (1. 0 kg-m , 7 Ib-ft )
ProCarManuals.com

A/C Syste m Servic e
Performanc e Tes t
The performanc e tes t wil l hel p determin e i f th e ai r con -
ditionin g syste m is operatin g withi n specifications .
Only us e servic e equipmen t tha t i s U.L.-liste d an d is cer -
tifie d t o mee t th e requirement s o f SA E J221 0 t o remov e
HFC-134 a (R-134a ) fro m th e ai r conditionin g system .
CAUTION : Exposur e t o ai r conditione r refrigeran t
an d lubrican t vapo r o r mis t ca n irritat e eyes , nos e
an d throat . Avoi d breathin g th e ai r conditione r
refrigeran t an d lubrican t vapo r o r mist .
I f accidenta l syste m discharg e occurs , ventilat e wor k
are a befor e resumin g service .
R-134 a servic e equipmen t o r vehicl e ai r conditionin g sys -
te m shoul d no t b e pressur e teste d o r lea k teste d wit h
compresse d air .
Som e mixture s o f ai r an d R-134 a hav e
bee n show n to b e combustibl e a t elevate d pressure s
an d ca n resul t i n fir e o r explosio n causin g injur y o r
propert y damage . Neve r us e compresse d ai r t o pres -
sure tes t R-134 a servic e equipmen t o r vehicl e ai r
conditionin g systems .
Additiona l healt h an d safet y informatio n ma y b e obtaine d
fro m th e refrigeran t an d lubrican t manufacturers .
1 . Connec t a R-134 a refrigeran t Recovery/Recycl -
ing/Chargin g Syste m to th e ca r a s show n followin g
th e equipmen t manufacturer' s instructions .
2 . Inser t a thermomete r i n th e cente r ven t outlet .
Determin e th e relativ e humidit y an d ai r
temperatur e b y callin g th e loca l weathe r informa -
tion line .
3. Tes t conditions :
• Avoi d direc t sunlight .
• Ope n engin e cover .
• Ope n fron t doors .
• Se t th e temperatur e contro l dia l t o MA X COO L
an d pus h th e mod e contro l butto n t o VEN T an d
FRES H button .
• Tur n th e fa n switc h t o MAX .
• Ru n th e engin e a t 1,50 0 RPM .
• N o drive r o r passenger s i n vehicle .
4 . Afte r runnin g th e ai r conditionin g fo r 1 0 minute s
unde r th e abov e tes t conditions , rea d th e deliver y
temperatur e fro m th e thermomete r i n th e das h ven t
an d th e hig h an d low syste m pressur e fro m th e A/ C
gauges .
Recovery/Recycling/Chargin g Syste m
ProCarManuals.com

Recovery

Only use service equipment that is U.L.-listed and is cer-

tified to meet the requirements of SAE J2210 to remove

HFC-134a (R-134a) from the air conditioning system.

CAUTION: Exposure to air conditioner refrigerant

and lubricant vapor or mist can irritate eyes, nose

and throat. Avoid breathing the air conditioner

refrigerant and lubricant vapor or mist.

If accidental system discharge occurs, ventilate work

area before resuming service.

R-134a service equipment or vehicle air conditioning sys-

tem should not be pressure tested or leak tested with

compressed air.

Some mixtures of air and R-134a have

been shown to be combustible at elevated pressures

and can result in fire or explosion causing injury or

property damage. Never use compressed air to pres-

sure test R-134a service equipment or vehicle air

conditioning systems.

Additional health and safety information may be obtained

from the refrigerant and lubricant manufactures.

1. Connect a R-134a refrigerant Recovery/Recycl-

ing/Charging System to the car as shown following

the equipment manufacturer's instructions.

2. Measure the amount of refrigerant oil removed

from the A/C system after the recovery process is

completed.

NOTE: Be sure to install the same amount of new

refrigerant oil back into the A/C system before

charging.
Recovery/Recycling/Charging System.ProCarManuals.com

A/C System Service

Evacuation

Only use service equipment that is U.L.-listed and is cer-

tified to meet the requirements of SAE J2210 to remove

HFC-134a (R-134a) from the air conditioning system.

CAUTION: Exposure to air conditioner refrigerant

and lubricant vapor or mist can irritate eyes, nose

and throat. Avoid breathing the air conditioner

refrigerant and lubricant vapor or mist.

If accidental system discharge occurs, ventilate work

area before resuming service.

R-134a service equipment or vehicle air conditioning sys-

tem should not be pressure tested or leak tested with

compressed air.

Some mixtures of air and R-134a have

been shown to be combustible at elevated pressures

and can result in fire or explosion causing injury or

property damage. Never use compressed air to pres-

sure test R-134a service equipment or vehicle air

conditioning systems.

Additional health and safety information may be obtained

from the refrigerant and lubricant manufacturers.

1. When an A/C System has been opened to the at-

mosphere, such as during installation or repair, it

must be evacuated using a R-134a refrigerant

Recovery/Recycling/Charging System. (If the

system has been open for several days, the

receiver/dryer should be replaced).

2. Connect a R-134a refrigerant Recovery/Recycl-

ing/Charging System to the car as shown follow

the equipment manufacturer's instructions.

NOTE: If low pressure does not reach more than

700 mm Hg (27 in-Hg) in 1 5 minutes, there is pro-

bably a leak in the system. Partially charge the

system and check for leaks (see Leak Test).
Recovery/Recycling/Charging SystemProCarManuals.com