A/C SYSTEM SPECIFICATIONS
| CAUTION | When discharging air conditioning system, use only approved refrigerant recovery/recycling equipment. Make every attempt to avoid discharging refrigerant into the atmosphere. |
| Application | Specification | |
|---|---|---|
| Compressor Type | Atsugi Rotary Vane | |
| Compressor Belt Deflection | ||
| New Belt | 5/32-13/64" (4-5 mm) | |
| Used Belt | 13/64-15/64" (5-6 mm) | |
| System Oil Capacity | 6.8 ozs. | |
| Refrigerant (R-12) Capacity | 26-30 ozs. | |
| System Operating Pressures (1) | ||
| High Side | 185 psi (13.0 kg/cm 2 ) | |
| Low Side | 25 psi (1.75 kg/cm 2 ) | |
| (1) Measured at ambient temperature of 77°F (25°C), with 50 percent relative humidity. | ||
| (1) | Measured at ambient temperature of 77°F (25°C), with 50 percent relative humidity. |
SPECIFICATIONS
DESCRIPTION
A separate evaporator housing assembly is combined with a standard heater core assembly to create an integrated A/C-heating unit. Blower motor directs airflow through evaporator and then through the heater core to ducting and outlets.
CONTROL PANEL & SYSTEM OPERATION
Desired air control mode is achieved by push buttons on A/C-heater control panel. Air intake control can be set for RECIR (recirculated) or OUTSIDE air entry. A/C switch and fan controls are independent of mode controls. System operation for control panel are as follows
VENT/RECIR Mode; A/C OFF, Fan ON; COLD Temp. Setting
Recirculated air discharged through dashboard outlets. No outside air entry. No temperature variation. Heater control valve closed.
VENT/RECIR Mode; A/C ON; Fan ON; COLD Temp. Setting
Air discharged (recirculated) at cold temperature. Heater control valve closed. Fast idle actuator on. Air discharged through dashboard outlets.
VENT/OUTSIDE Mode; A/C OFF; Fan ON
Outside air drawn in. Heater control valve closed. Fast idle actuator off. Discharged air temperature same as outside air. Air discharged through dashboard outlets.
BI-LEVEL/OUTSIDE Mode; A/C OFF; Fan ON
Outside air drawn in. Floor and dashboard outlet air is warm-to-cool, depending on temperature lever setting. Heater control valve open-to-closed, depending on temperature lever setting.
HEAT/OUTSIDE Mode; A/C OFF; Fan ON; HEAT Temp.
Setting Outside air drawn in. Floor outlet air warm-to-cool, depending on temperature lever setting. Heater control valve open-to-closed, depending on temperature lever setting. If equipped, a fresh air ventilation lever may be pushed to allow outside cool air to face-vent outlets while still allowing heated air to floor outlets.
DEF/OUTSIDE Mode; A/C OFF; Fan ON; HEAT Temp. Setting
Outside air drawn in. Defroster outlet air cool-to-warm, depending on temperature lever setting. Heater control valve open, depending on temperature lever setting. A/C compressor operates intermittently to stabilize interior windshield air temperature and reduce fogging of windshield.
CONDENSER & COOLING FAN RELAYS
Condenser and radiator cooling fan relays have Blue outer case and are located within engine compartment relay boxes.
Typical system consists of condenser and radiator cooling fans controlled by 3 relays. Relay No. 1 is used low-speed operation, while relay No. 2 and relay No. 3 are for high-speed operation. Relay grounds are controlled by Engine Concentrated Control System (ECCS).
HIGH & LOW PRESSURE CUT-OFF SWITCH
The high and low (dual) pressure cut-off switch, normally mounted on receiver-drier, protects A/C system from high pressure build-up due to restriction, overcharge or compressor malfunction. If excessively low or high system pressure is sensed, the switch electrically stops compressor clutch operation.
HIGH PRESSURE/TEMPERATURE RELIEF VALVE
A high pressure/temperature relief valve is mounted on receiver-drier. When high pressure of 540 psi (38 kg/cm 2 ) or temperature of 210°F (105°C) is sensed, relief valve opens, venting refrigerant to atmosphere.
THERMO CONTROL AMPLIFIER
An electrical thermo control amplifier is mounted on evaporator housing. A temperature sensor (thermistor), inside evaporator housing, senses air temperature and sends signal to thermo control amplifier. Thermo control amplifier then cycles compressor clutch on and off, according to temperature lever setting on control panel.
ACCELERATION CUT SYSTEM
This system monitors vacuum in intake manifold. When engine is under heavy load (low vacuum condition), A/C compressor is turned off for 5 seconds to reduce engine load.
FAST IDLE CONTROL DEVICE (FICD)
When A/C system is energized, the engine control module signals FICD to adjust Auxiliary Air Control (AAC) valve to by-pass additional air and increase idle speed. This higher idle speed allows engine to idle smoothly during compressor operation.
THERMAL PROTECTOR SWITCH
The thermal protector switch, installed in A/C compressor at evaporator refrigerant line inlet, incorporates a pressure diaphragm switch and temperature sensor. When refrigerant temperature increases, temperature sensitive gas inside temperature sensor expands, causing diaphragm switch to open electrical circuit to A/C compressor.
SERVOMOTORS
Electric servomotors control intake air, air mode and air mix doors to distribute conditioned air to passenger compartment.
ADJUSTMENTS
Note. For control cable and door rod adjustments, see HEATER SYSTEM article in the AIR CONDITIONING & HEAT Section.
TROUBLE SHOOTING
Use the following charts to diagnose A/C system problems. Start with PRELIMINARY CHECKS and then proceed to appropriate DIAGNOSTIC PROCEDURES charts.
Note. The following diagnostic charts are courtesy of Nissan Motor Co., U.S.A.
PRELIMINARY CHECKS
See PRELIMINARY CHECKS table below and the applicable Figs.
| Preliminary Check | Cause/Symptom | Figure |
|---|---|---|
| 1 | Intake Door Not Set at FRESH in DEFROST or FOOT/DEFROST Mode | (Scheme 1) |
| 2 | A/C Does Not Blow Cold Air | (Scheme 2) |
| 3 | Magnetic Clutch Does Not Engage in DEFROST Mode | (Scheme 3) |
| 4 | Air Outlet Does Not Change | (Scheme 4) |
| 5 | Moise | (Scheme 5) |
| 6 | Power Supply Circuit Check For A/C System | (Scheme 6) |
PRELIMINARY CHECKS
Preliminary Check 1 Flow Chart. Scheme 1
Preliminary Check 2 Flow Chart. Scheme 2
Preliminary Check 3 Flow Chart. Scheme 3
Preliminary Check 4 Flow Chart. Scheme 4
PRELIMINARY CHECK 5 - Noise
Preliminary Check 5 Flow Chart. Scheme 5
Push Control Unit Check
- Disconnect push control unit harness connector.
- Turn ignition switch to ACC position.
- Using voltmeter, ensure battery voltage at terminal No. 14 of harness connector.
- Turn ignition switch to OFF position.
- Using ohmmeter, ensure continuity between terminal No. 17 of harness connector and ground.
Thermo Control Amplifier Check
- Disconnect thermo control amplifier harness connector.
- Turn ignition switch to ON position.
- Using voltmeter, ensure battery voltage exists at terminal No. 34 of harness connector.
- Turn ignition switch OFF. Turn A/C and FAN switches ON.
- Using ohmmeter, ensure continuity exists between terminal No. 13 of harness connector and ground.
Preliminary Check 6. Scheme 6
DIAGNOSTIC PROCEDURES
See DIAGNOSTIC PROCEDURES table and the applicable Figures.
| Procedure | Cause/Symptom | Figure(s) |
|---|---|---|
| 1 | Blower Motor Does Not Rotate | (Scheme 7)to (Scheme 9) |
| 2 | Air Outlet Does Not Change | (Scheme 10)to (Scheme 11) |
| 3 | Intake Door Does Not Change in VENT, BI-LEVEL or FOOT Mode | (Scheme 12) |
| 4 | Compressor (Magnet) Clutch Does Not Engage With A/C & FAN Switches On | (Scheme 13)to (Scheme 16) |
| 5 | Illumination or Indicators of Push Control Unit Do Not Come On | (Scheme 17)to (Scheme 22) |
DIAGNOSTIC PROCEDURES
Diagnostic Procedure 1 Flow Chart (1 of 3). Scheme 7
Diagnostic Procedure 1 Flow Chart (2 of 3). Scheme 8
Diagnostic Procedure 1 Flow Chart (3 of 3). Scheme 9
Diagnostic Procedure 2 Flow Chart (1 of 2). Scheme 10
Diagnostic Procedure 2 Flow Chart (2 of 2). Scheme 11
Diagnostic Procedure 3 Flow Chart. Scheme 12
Diagnostic Procedure 4 Flow Chart (1 of 4). Scheme 13
Diagnostic Procedure 4 Flow Chart (2 of 4). Scheme 14
Diagnostic Procedure 4 Flow Chart (3 of 4). Scheme 15
Diagnostic Procedure 4 Flow Chart (4 of 4). Scheme 16
DIAGNOSTIC PROCEDURE 5 - ILLUMINATION OR INDICATORS OF PUSH CONTROL UNIT DO NOT COME ON
Note. Perform PRELIMINARY CHECK 7 before referring to the following flow chart.
Diagnostic Procedure 5 Flow Chart (1 of 6). Scheme 17
Diagnostic Procedure 5 Flow Chart (2 of 6). Scheme 18
Diagnostic Procedure 5 Flow Chart (3 of 6). Scheme 19
Diagnostic Procedure 5 Flow Chart (4 of 6). Scheme 20
Diagnostic Procedure 5 Flow Chart (5 of 6). Scheme 21
Diagnostic Procedure 5 Flow Chart (6 of 6). Scheme 22
A/C SWITCH
Disconnect negative battery cable. Remove A/C switch from control panel. Depress A/C switch on. Using an ohmmeter check for continuity between switch terminals. Continuity should exist. If no continuity exists, replace A/C switch.
BLOWER SPEED CONTROL SWITCH
To check fan blower switch for proper operation, check for continuity between switch terminals. See BLOWER SPEED CONTROL SWITCH under TESTING in HEATER SYSTEM article in the AIR CONDITIONING & HEAT Section.
BLOWER MOTOR RESISTOR
To check blower motor resistor for proper operation, disconnect harness connector and ensure continuity exists between all resistor terminals. If continuity does not exist, replace resistor.
RELAYS
Remove relay to be tested. (Scheme 26) Apply battery voltage between terminals No. 1 and No. 2. Check for continuity between remaining relay terminals. Continuity should exist. (Scheme 23) If no continuity exists, replace relay.
Scheme 23
BLOWER MOTOR
Disconnect wiring harness at blower motor. Apply battery voltage to blower motor terminals. Ensure blower motor operation is smooth. If blower motor operation is rough or not up to speed, replace blower motor.
DUAL PRESSURE SWITCH
Remove dual pressure switch connector. Dual pressure switch is located on top of receiver-drier. Using an ohmmeter, check continuity between dual pressure switch terminals as indicated in the DUAL PRESSURE SWITCH SPECIFICATIONS table. Replace switch if it does not perform as indicated.
| High Side Pressure psi (kg/cm 2 ) | System Operation | Continuity |
|---|---|---|
| Decreasing To 26-31 (1.8-2.2) | Off | No |
| Increasing To 356-412 (25-29) | Off | No |
| Increasing To 26-34 (1.8-2.4) | On | Yes |
| Decreasing To 270-327 (19-23) | On | Yes |
DUAL PRESSURE SWITCH SPECIFICATIONS
Check thermo control amplifier as specified in THERMO CONTROL AMPLIFIER SPECIFICATIONS table. Replace amplifier if it does not perform as indicated.
| Evaporator Temperature °F (°C) | Thermo Amplifier Operation | Volts |
|---|---|---|
| Decreasing To 37-38 (2.5-3.5) | Off | About 12 |
| Increasing To 39-41 (4-5) | On | Zero |
THERMO CONTROL AMPLIFIER SPECIFICATIONS
Check compressor operation with temperature of compressor as specified in THERMAL PROTECTOR SWITCH SPECIFICATIONS table. Replace switch if it does not perform as indicated.
| Compressor Temperature °F (°C) | Compressor Operation |
|---|---|
| Increasing To 275-293 (135-145) | Off |
| Decreasing To 248-266 (120-130) | On |
THERMAL PROTECTOR SWITCH SPECIFICATIONS
Removal
Loosen idler pulley bolt and remove compressor belt. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect compressor clutch lead. Remove discharge and suction hoses from compressor and plug hose openings. Remove compressor mounting bolts and compressor.
Installation
To install, reverse removal procedure. Use new "O" rings, coated with refrigerant oil, when attaching hoses to compressor. Evacuate and recharge system.
Scheme 24
Scheme 25
- Discharge A/C system using approved refrigerant recovery/recycling equipment. Drain cooling system. Disconnect negative battery cable. Remove center console by prying up shift lever cover and console center cover to access and remove console retaining screws.
- Remove steering column covers and left side lower dashboard panel. Remove fuse block and disconnect instrument cluster harness connector. Remove glove box door, glove box, and right side lower dashboard panel. (Scheme 24)
- Remove instrument switches panel faceplate. Remove instrument cluster lid and air vent outlet assembly.
- Cover Head-Up display reflective surface on windshield (if equipped). Remove instrument cluster and Head-Up display cover. Remove defroster grilles by carefully prying center pawl upward, then slide grilles toward center and lift out. Remove dashboard retaining screws from under defroster grilles and from both outside lower corners.
- Remove A/C-heater control panel retaining screws. Remove dashboard center console section and side covers. Note all wiring harnesses and A/C-heater control cable locations. Lift upward and outward on right side dashboard to remove blower and intake housing assembly. (Scheme 25)
- In engine compartment, disconnect A/C lines from evaporator and remove heater hoses from heater core. Lift upward and outward on right side dashboard to remove evaporator assembly. Disconnect all ducts and remove heater unit. Remove spring clip retainers and separate heater unit halves to remove heater core.
To install, reverse removal procedure. Use new "O" rings, coated with refrigerant oil, before assembling connections. If installing a new evaporator core, add 2 ozs. (60 cc) of refrigerant oil to new core before installation. Evacuate and recharge system.
Drain cooling system. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect radiator hoses and wiring harness. Remove radiator cooling fan, shroud assembly and radiator. Remove front grille and disconnect refrigerant lines from condenser and receiver-drier. Remove condenser.
To install, reverse removal procedure. Use new "O" rings, coated with refrigerant oil, before assembling connections. Add 2 ozs. (60 cc) of refrigerant oil to new condenser before installation. Evacuate, recharge and leak test system.
Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove front grille to access receiver-drier. Disconnect low pressure switch connector (if equipped). Disconnect A/C lines from receiver-drier and plug openings. Remove screws and receiver-drier.
To install, reverse removal procedure. Use new "O" rings, coated with refrigerant oil, before assembling connections. Add 1 oz. (30 cc) of refrigerant oil to new receiver-drier before installation. Evacuate, recharge and leak test system.
Scheme 26
Manual A/C-Heater System Wiring Diagram. Scheme 27
See also:
• PRELIMINARY CHECKS
• PRELIMINARY CHECKS