climate control ACURA NSX 1991 Service Repair Manual

Engine Coolant Refilling and Bleeding

CAUTION: When pouring engine coolant, be sure to

shut the relay box lid and not let coolant spill on the

electrical parts or the paint. If any coolant spills, rinse it

off immediately.

NOTE:

• Perform this maintenance when the engine is cool.

• Before replacing the coolant, turn the ignition ON,

slowly turn the climate control temperature knob to

90° and turn off the ignition. This will allow the

coolant in the heater to drain out with the rest of the

system.
1. Open the hood, the rear window and the engine

cover.

2. Remove the cover protecting the water pipes and

shift cables on the underside of the car.

3. Before removing the expansion tank cap, first

loosen the cap to lower pressure.

CAUTION: Do not remove the expansion tank cap

when engine is hot. The coolant is under pressure

and may blow out and scald you. Open the cap

slowly when the engine is cool.

4. Loosen the drain plug in the bottom of the radiator,

and drain the coolant.

5. Remove the two drain bolts from the water pipes,

and drain the coolant.

WASHERS

Replace.

DRAIN BOLTS

15 N-m (1.5 kg-m, 11 Ib-ft)
DRAIN HOLE
DRAIN PLUGProCarManuals.com

Climate control unit, stereo cassete/radio and glove box removal:

Disassemble in numbered sequence.

NOTE: Remove the center console panel.

CLIMATE CONTROL

UNIT

Disconnect the connectors.

SRS UNIT

Passenger's:
STEREO

CASSETE RADIO

Disconnect the connectors.

GROUND CABLE

GLOVE BOX
Disconnect the connectors.

TRUNK LID OPENER

MAIN SWITCH
PASSENGER'S

AIRBAG

DLC

CONNECTOR

GLOVE BOX

LID

DASHBOARD LOWER

COVER (Passenger's)

Installation is the reverse of the removal procedure.

NOTE: Make sure the connectors are connected properly.ProCarManuals.com

Replacement

NOTE:
Remove the access panel, then remove the
short connector (RED). Disconnect the connec-
tor between the airbag and cable reel, then con-
nect the short connector (RED) to the airbag
connector.

AIRBAG

CONNECTOR
CABLE REEL

CONNECTOR

ACCESS PANEL
SHORT CONNECTOR
(RED)

Connect the special tool to the cable reel
connector.

CABLE REEL

CONNECTOR

SHORT

CONNECTOR

(RED)
SHS

SERVICE CONNECTOR

07MAZ–SP00200

(cont'd)

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. To remove the dashboard, first remove the: Seats (see page 20-39 ('93-'96), 38)
Dashboard lower cover (Driver's) (see page
20-54('94-'96) ('91-'93))
Dashboard lower pad (see page 20-54('94-'96) ('91-'93))

Dashboard brace (see page 20-54('94-'96)('91-'93))

Cente
r
armrest (see page 20-49('94-'96)('91-'93))


Clock, center air vent and console panel (see
pages 20-50('94-'96) ('91-'93), 51('94-'96) ('91-'93)

52('94-'96) ('91-'93))

Climate control unit and stereo elassette/ratio (see
page 20-53('94-'96)('91-'93))
Dashboard lower cover (Passenger's) (see page
20-53('94-'96) ('91-'93))

Glove box lid and glove box (see page 20-53('94-'96)('91-'93))

2. Lower the Steering column (see section 17).
To avoid accidental deployment and
possible injury always install the short connector on the airbag connector when the SRS wire
harness is disconnected.ProCarManuals.com

('93-'96), 86 ('91-'92 Models)
MODE CONTROL MOTOR
Replacement, page 22-57
('93-'96), 69 ('91-'92 Models)
Test, page 22-58
('93-'96), 91 ('91-'92 Models)
"DEF" DOOR
Adjustment, page 22-77
('92-'96), 72 ('91Models)

"HEAT" DOOR

Adjustment, page 22-77
('92-'96), 72 ('91Models)

RECIRCULATION

CONTROL MOTOR

Replacement, page 22-59 ('93-'96), 64 ('91-'92)
Test, page 22-59 ('93-'96), 64 ('91-'92 Models)

BLOWER UNIT

Replacement, page 22-67 ('93-'96), 63 ('91-'92)Overhaul, page 22-68 ('93-'96), 62 ('91-'92)


RECEIVER/DRYER

Serves as a reservoir which filters and
removes moisture from the refrigerant.
OUTSIDE AIR TEMPERATURE SENSOR

Removal, page 22-62 ('93-'96), 86 ('91-'92 Models)

Test, page 22-62


DUAL CONDENSER

Dissipates the heat which was

absorbed by the refrigerant.

Replacement, page 22-79 ('93-'96), 74 ('91Models)Overhaul, page 22-80 ('93-'96), 75 ('91Models)

HEATER CORE

TEMPERATURE SENSOR
Removal, page 22-64

Test, page 22-64
AIR MIX CONTROL

MOTOR

Replacement, page 22-56 ('93-'96), 70 ('91-'92 Models)
Test, page 22-57 ('93-'96), 69 ('91-'92 Models)

HEATER-EVAPORATORUNIT
Replacement, page 22-74('93-'96), 66 ('91-'92 Models)
Overhaul, page 22-76 ('93-'96), ('92), 71 ('91 Models) IN-CAR TEMPERATURE SENSOR
Removal, page 22-61('93-'96), 69 ('91-'92 Models)
Test, page 22-61 ('93-'96), 69 ('91-'92 Models)
COMPRESSOR (NIPPONDENSO)
Compresses the refrigerant and

then forces it through the condenser.

CLIMATE CONTROL UNIT
Replacement, page 22-54
Adjustment, page 22-55
SUNLIGHT SENSOR

Removal, page 22-63 ('93-'96), 87 ('91-'92 Models)Test, page 22-63 ('93-'96), 87 ('91-'92 Models)

EVAPORATOR

TEMPERATURE

SENSOR

Removal, page 22-65 ('93-'96), 88 ('91-'92 Models)
Test, page 22-65 ('93-'96), 88 ('91-'92 Models)

HEATER VALVE CABLE

Adjustment, page 22-58 ('93-'96),
91 ('91-'92), 75 ('93-'96), 66 ('91-'92)

VENT DOOR CONTROL MOTOR
Replacement, page 22-60

('93-'96)
, 69 ('91-'92 Models)
Test, page 22-60 ('93-'96),
69 ('91-'92 Models)

A/C TRIPLE
PRESSURE SWITCHProCarManuals.com

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.

POWER TRANSISTORBLOWER MOTOR

RECIRCULATION

CONTROL
MOTOR

CONDENSER
FAN MOTOR UNDER-HOOD RELAY BOX A
(CONDENSER FAN RELAY, COMPRESSOR CLUTCH RELAY,
BLOWER MOTOR HIGH RELAY, BLOWER MOTOR RELAY)
UNDER-HOOD

FUSE/RELAY

BOX

HEATER CORE TEMPERATURE SENSOR
CLIMATE CONTROL UNIT VENT DOOR
CONTROL MOTOR
OUTSIDE AIR
TEMPERATURE SENSOR ENGINE COMPARTMENT

FUSE/RELAY BOX
A/C TRIPLE PRESSURE SWITCH
FAN CONTROL UNIT (Fan radiator and con-

denser fans inside car,

behind seats)
EVAPORATOR

TEMPERATURE

SENSOR

IN-CAR

TEMPERATURE
SENSOR
MODE CONTROL

MOTOR

AIR MIX CONTROL MOTOR
SUNLIGHT

SENSORProCarManuals.com

Troubleshooting

Self-diagnosis Circuit Check
The Automatic Climate Control System has a built-in self diagnosis feature. To run it, turn the ignition switch ON (II),
then turn the fan speed dial to the AUTO position. Set the temperature control dial to 60° F(18°C), then gradually move

0

th
e
dial up the temperature range to 90°F (32°C). At each temperatu\
re setting, push both the AUTO and OFF burtons
o

n
the control unit at the same time. Wait for at least one minute for the\
system to readjust and check for problems.

If any problems are found in circuits "A" through "I", the system will indicate which circuit has the problem by lighting

the respective indicator light.
NOTE: The climate control unit does not memorize which self-diagnosis indicator lights come on. If you turn the ig-

nition switch OFF, the indicator light memory will be lost.

AUTO BUTTON

OFF BUTTON

TEMPERATURE CONTROL DIAL
TEMP DISPLAY


FAN SPEED DIAL

NOTE:
When you turn the ignition switch OFF, the self-diagnosis function will be canceled. After completing repair work, run the self-diagnosis again to make sure that there are no other malfunctions.COMPONENT WITH PROBLEM
IN-CAR TEMPERATURE SENSOR
OUTSIDE AIR TEMPERATURE

SENSOR

SUNLIGHT SENSOR
HEATER CORE TEMPERATURE

SENSOR

EVAPORATOR TEMPERATURE

SENSOR

AIR MIX CONTROL MOTOR
MODE CONTROL MOTOR
RECIRCULATION CONTROL MOTOR
VENT DOOR CONTROL MOTOR
POSSIBLE CAUSE

Open or short circuit

Open or short circuit

Open or short circuit

Open or short circuit

Open or short circuit

Open or short circuit

Air mix door stuck

Open position signal circuit

Mode door stuck

Open position signal circuit

Open or short circuit

Vent door stuck
Refer to PAGE

22-16

22-1

8

22-20
22-22
22-24
22-2
6
22-28
22-30
22-32
INDICATOR

MODE

A/C
ON
(A/C)

OFF
(A/C)

LED on

defroster

button

A

B

C
D

E

F

G
H
I
ProCarManuals.com

Function Selection and Operation Check

This check will quickly and automatically select and operate all functions of the climate control system, in the combina-

tions and sequence shown below. It may help clarify a problem, or identify one that didn't show up when you perform

the self-diagnosis circuit check.

Turn the FAN switch to AUTO, then push in both the MODE and AUTO buttons and hold them in while you start the

engine. The control unit will then automatically run the check in eight steps, one step every five seconds.

To stop at one of those steps, push the MODE button; to continue, push it again for each step after that.

Pushing the OFF button or turning the ignition OFF, will turn off the check.

Check the temperature, volume, and source of the air flow, and compare it to what the chart shows it should be.ProCarManuals.com

5. Remove the three screws and center console

panel, then disconnect the 3P connector and 4P

connector from the floor wire harness.

6. Remove the four screws, then disconnect the 14P

and 30P connectors from the floor wire harness.

Take out the automatic climate control unit.ProCarManuals.com

Mode Control Motor

Test

1. Disconnect the mode control motor connector, turn

the ignition switch ON (II), and move the blower

switch to the middle setting.

2. Connect battery power to the No. 1 terminal of the

mode control motor, then connect ground to the No.

2 terminal. The mode control motor should run, and

stop at VENT.

If it doesn't, reverse the connections; the mode

control motor should run, and stop at DEF.

NOTE: If the mode control motor does not run,

remove it, and check the mode control linkage and

doors for smooth movement. If the mode control

linkage and doors move smoothly, replace the

mode control motor.
3. Plug the connector back into the motor. Operate

the mode switch on the climate control unit to each

mode. Verify that the mode control motor has mov-

ed to the selected position by checking the air flow

for the mode selected.

NOTE: If the motor did not move, turn the ignition

switch OFF, and disconnect the mode control mo-

tor connector. Turn the ignition switch ON (II), then

connect battery power to No. 1 and No. 2 terminals

as shown in step 2. Power the mode control motor

to move the doors to the mode selected.

4. Disconnect the mode control motor connector at

each mode selected and check for continuity bet-

ween the motor terminals according to the table

below.

5. Replace the mode control motor if there is no con-

tinuity for any one mode selected.ProCarManuals.com

Relay and Control Unit Locations

Dashboard

TURN SIGNAL/HAZARD

RELAY
CLIMATE CONTROL UNIT

UNDER-DASH FUSE BOX
FOOT WELL LIGHT

DASHBOARD

LOWER COVER

INTEGRATED

CONTROL UNIT
SRS UNITProCarManuals.com