1991 ACURA NSX Service Repair Manual

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 )
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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
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5. To complete the charts:

• Mark the delivery temperature along the vertical

line.

• Mark the intake temperature (air temperature)

along the bottom line.

• Draw a line straight up from the air temperature

to the humidity.

• Mark a point one line above and one line below

the humidity level. (10% above and 10% below

the humidity level)

• From each point, draw a horizontal line across to

the delivery temperature.

• The delivery temperature should fall between the

two lines.

• Complete the low side pressure test and high side

pressure test in the same way.
USA:

DELIVERY

PRESSURE

INTAKE

PRESSURE

DELIVERY

TEMPERATURE

Canada

DELIVERY

PRESSURE

DELIVERY

TEMPERATUREProCarManuals.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

Heater-Evaporator Unit

Replacement

SRS components are located in this area. Review the SRS
component locations, precautions, and procedures in the
SRS section (24) before performing repairs or service.
1.
Remove
the
blower
unit
(see
page
22-67 ('93-'96),
63('91-'92)).

2. When the engine is cool, drain the engine coolant from the radiator (see section 10).
Do not remove the radiator cap when

the engine is hot; the engine coolant is under

pressure and could severely scald you.

CAUTION: Engine coolant will damage paint. Quick-

ly rinse any spilled engine coolant off painted sur-

faces.
3. Disconnect the heater valve cable from the heater valve.

4.
Disconnect
the
heater hoses. Engine cootant
will
run out when the hoses are disconnected, drain it
into a clean drip pan.

HEATER

VALVE CASLE
HEATER VALVE
5. Recover the refrigerant from the A/C system with a
R-134a refrigerant Recovery/Recycling/Charging
System. (see page 22-73).
6. Disconnect the receiver line and the suction line from the evaporator. Cap the open fittings immediately
to keep moisture out of the system.

RECEIVER LINE

New parts (R-134a)

SECTION LINE

7. Remove the dashboard (see section 20).
8. Remove the heater duct. 9. Remove the four mounting bolts, disconnect the con-
nectors from the control units and the evaporator

temperature sensor connector from the control unit

bracket, then remove the control unit bracket.
*: CORROSION RESISTANT BOLT
EVAPORATOR

TEMPERATURE
SENSOR CONNECTOR
CONTROL

UNIT

BRACKET
SRS MAIN

HARNESS

* 6 x 1,0 mm
10 N·m
(1.0 kg-m,
7 Ib-ft)

* 6 x 1.0 mm
10 N·m (1.0 kg-m, 7 Ib-ft)
10. Remove the woofer enclosure (see section 23).ProCarManuals.com

11. Disconnect the connectors from all the control
motors and sensors attached to the heater-
evaporator unit.

12. Remove the two mounting bolts and two nuts, then
remove the heater-evaporator unit through the
passenger door.
: CORROSION RESISTANT
BOLT
HEATER-EVAPORATOR UNIT
NUTS
30 N·m
(3.0 kg-m,

22 Ib-ft)

SRS UNIT

6 x 1.0 mm
10 N·m (1.0 kg-m, 7 Ib-ft)

13. Install the heater-evaporator unit in the reverse order of removal, and:
If you're installing a new evaporator, add

refrigerant oil (ND-OIL 8) see page 22-69 .
Replace 0-rings with new ones at each fitting,
and apply refrigerant oil to them.
NOTE: Be sure to use the right 0-rings for
R-134a to avoid leakage.

14. Fill the radiator and reservoir tank with the proper

engine coolant mixture. Bleed the air from the cool-
ing system (see section 10).
CAUTION: Follow the sequence described in the air
bleed procedure. If you don't, you may leave air in

the system which could damage the engine.
15. If necessary, adjust the heater valve cable:
Set the air mix control motor at COOL position
(see page 22-57) .
Connect the end of the heater valve cable to the
heater valve arm. Gently slide the cable outer housing back from
the end enough to take up any slack in the cable,
bu
t not enough to make the other end move the
arm on the air mix control motor. Then snap the
clamp down over the cable housing.

CLAMP

HEATER VALVE

ARM

HEATER VALVE

CABLE

16. Turn the blower on, and make sure that there is no air leakage.
17. Charge the system (see page 22-91), and test per- formance (see page 22-70).ProCarManuals.com

Heater-Evaporator Uni t
Overhau l
1. Remov e th e heate r cor e cover , remov e th e pip e clamp , the n pul l ou t th e heate r core .
2 . Remov e th e lowe r hal f o f th e housing , the n remov e th e evaporator .
3 . Remov e th e expansio n valv e i f necessary .
HEATER COR E PIPE CLAM P
AI R MI X DOO R
LOWE R HAL F
OF TH E HOUSIN G
CAPILLAR Y TUB E
SUCTIO N LIN E
*EVAPORATOR
The expansio n valv e capillar y tub emus t b e touchin g th e suctio n line .
New par t fo r R-134a .
4. Assembl e th e heater-evaporato r uni t i n th e revers e orde r o f disassembly . Hol d th e expansio n valv e capillar y tub e
dow n agains t th e suctio n line , an d wra p i t wit h tap e t o hol d i t there .
EXPANSIO N VALV E HEATE
R COR E
COVE R
TAPE
SUCTIO N LIN E
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"DEF" Door Adjustment

Connect the control rod to

the clip.
Turn this lever all the way

clockwise and hold it there.

Turn this lever clockwise

and hold it against its stop.
"HEAT" Door Adjustment

Reposition gear 2 so this

mark lines up with the mark .

on gear 1 Loosen this screw in gear 2.

GEAR 1
GEAR 2ProCarManuals.com