A/c-Heater System - Manual Acura Integra III

A/C SYSTEM SPECIFICATIONS

Note. Before removing radio, obtain anti-theft code number from customer. After servicing, turn radio on. When the word CODE is displayed, enter 5-digit code to restore radio operation.

A/C SYSTEM SPECIFICATIONS

DESCRIPTION

This is a cycling-clutch system that uses an expansion valve to control refrigerant flow. (Scheme 1)and (Scheme 9). The blower motor, heater core and evaporator are located under the instrument panel.

Scheme 1

AIRFLOW DOORS

The air mix (temperature) door is controlled by a cable. The recirculation door (for fresh or recirculated air) and the mode door (for airflow direction) are controlled by electric motors.

A/C Compressor Clutch Relay

When the ECM grounds the coil circuit of the A/C compressor clutch relay, the relay contacts close, allowing current to flow to the compressor clutch.

Engine Control Module (ECM)

The ECM monitors the A/C request circuit, which includes the A/C pressure switch, A/C thermostat, A/C switch, and blower switch (heater fan switch). If the ECM senses that the A/C request circuit is grounded, it energizes the A/C compressor clutch relay.

A/C Pressure Switch

If refrigerant system pressure is less than 28 psi (2.0 kg/cm 2 ) or greater than 460 psi (32.3 kg/cm 2 ), the A/C pressure switch opens, interrupting the A/C request circuit.

A/C Thermostat

If evaporator temperature is 37°F (3°C) or less, the A/C thermostat opens, interrupting the A/C request circuit.

A/C Switch

When the A/C switch is turned on, the A/C request circuit (from the ECM) is grounded through the blower switch.

COOLING FANS

Power is supplied to the cooling fan motors (radiator fan and condenser fan) through relays. The coil circuit in each relay is grounded through the ECM or the Engine Coolant Temperature (ECT) switch. When coolant temperature exceeds 200°F (93°C), the contacts in the ECT switch close.

TROUBLE SHOOTING

Note. For trouble shooting procedures not covered in this article, see HEATER SYSTEM article.

RADIATOR FAN DOES NOT COME ON - CONDENSER FAN OKAY

1. Check fuse No. 33 (20-amp) in underhood fuse/relay block. If fuse is okay, remove and test radiator fan relay. See «RELAYS»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual__relays) under TESTING. If relay is okay, measure voltage between ground and terminal No. 3 of relay socket. (Scheme 2)
2. If battery voltage is not present, replace underhood fuse/relay block. If battery voltage is present, connect a jumper wire between terminals No. 1 and 3 of relay socket. If radiator fan comes on, go to step 5). If radiator fan does not come on, disconnect jumper wire.
3. Disconnect radiator fan connector. Check for continuity in Black/Red wire between radiator fan and terminal No. 1 of relay socket. If continuity does not exist, repair open Black/Red wire between radiator fan and underhood fuse/relay block. If continuity is present, go to next step.
4. Check for continuity in Black wire between radiator fan and ground. If continuity exists, replace radiator fan motor. If continuity does not exist, repair open Black wire between radiator fan and ground. If Black wire is okay, check for poor ground connections.
5. Disconnect jumper wire. Turn ignition on. Measure voltage between ground and terminal No. 4 of relay socket. If battery voltage is present, repair open Green wire between underhood fuse/relay block and A/C diode. If battery voltage is not present, repair open Black/Yellow wire between underhood fuse/relay block and underdash fuse/relay block.

Scheme 2

CONDENSER FAN DOES NOT COME ON - RADIATOR FAN OKAY

1. Remove and test condenser fan relay. See «RELAYS»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual__relays) under TESTING. If relay is okay, measure voltage between ground and White wire terminal of condenser fan relay connector.
2. If battery voltage is not present, repair White wire between underhood fuse/relay block and condenser fan relay. If battery voltage is present, connect a jumper wire between White and Blue/Black wire terminals of relay connector.
3. If condenser fan comes on, go to step 5). If condenser fan does not come on, disconnect jumper wire. Disconnect condenser fan connector. Check continuity in Blue/Black wire between condenser fan relay and condenser fan. If continuity exists, go to next step. If continuity does not exist, repair open Blue/Black wire between condenser fan and condenser fan relay.
4. Check for continuity in Black wire between condenser fan and ground. If continuity exists, replace condenser fan motor. If continuity does not exist, repair open Black wire between condenser fan and ground. If Black wire is okay, check for poor ground connections.
5. Disconnect jumper wire. Turn ignition on. Measure voltage between ground and Black/White wire terminal of relay connector. If battery voltage is not present, repair open Black/White or Black/Yellow wire between condenser fan relay and underdash fuse/relay block
6. If battery voltage is present, test A/C diode. See A/C DIODE under TESTING. If A/C diode is okay, repair open Blue/Yellow wire between condenser fan relay and A/C diode.

NEITHER FAN COMES ON

Test A/C diode. See A/C DIODE under TESTING. If A/C diode is okay, repair open Blue/Red wire between A/C diode and A/C pressure switch.

FANS COME ON WHEN A/C IS ON - BUT NOT FOR ENGINE COOLING

1. Turn ignition off. Unplug connector from Engine Coolant Temperature (ECT) switch. Turn ignition on. Measure voltage between ground and Green wire terminal. If battery voltage is not present, repair open Green wire between ECT switch and underhood fuse/relay block.
2. If battery voltage is present, turn ignition off. Check for continuity in Black wire between ECT switch and ground. If continuity exists, go to next step. If continuity does not exist, repair open Black wire between ECT switch and ground. If Black wire is okay, check for poor ground connections.
3. Check temperature gauge reading. If temperature gauge indicates coolant temperature is normal, repair cooling system. If temperature gauge indicates temperature is greater than normal, replace ECT switch.

Cooling Fans Run

1. Remove and test A/C compressor clutch relay. See «RELAYS»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual__relays) under TESTING. If relay is found to be faulty, replace relay. If relay is okay, measure voltage between ground and White wire terminal of relay connector. If battery voltage is not present, repair open White wire between underhood fuse/relay block and compressor clutch relay. If battery voltage is present, go to next step.
2. Connect a jumper wire between White wire and Red wire terminals of relay connector. If compressor clutch engages, go to next step. If compressor clutch does not engage, disconnect jumper wire. Disconnect compressor clutch connector. Check for continuity in Red wire between relay and clutch. If continuity is present, check compressor clutch clearance. If continuity does not exist, repair open Red wire between relay and clutch.
3. Disconnect jumper wire. Turn ignition on. Measure voltage between ground and Black/Yellow wire terminal of relay connector. If battery voltage is not present, repair open Black/Yellow wire between underdash fuse/relay block and compressor clutch relay. If battery voltage is present, go to next step.
4. Turn ignition off. Reconnect relay connector. Ensure A/C and heater fan switches are off. Turn ignition on. Using Backprobe Tool Set (07SAZ-001000A), measure voltage between ECM 32-pin connector terminal No. 17 and ground. (Scheme 3)
5. If battery voltage is not present, repair open Black/Red wire between relay and ECM. If battery voltage is present, measure voltage between ECM 31-pin connector terminal No. 5 and ground. (Scheme 3) If battery voltage is not present, repair open Blue/Red wire between A/C diode and ECM. If battery voltage is present, substitute known good ECM and retest. If battery voltage is not present with known good ECM, replace original ECM.

Scheme 3

Cooling Fans Do Not Run

1. Disconnect A/C pressure switch connector. Turn ignition on. Measure voltage between ground and Blue/Red wire terminal of A/C pressure switch connector. If battery voltage is not present, repair open Blue/Red wire between A/C pressure switch and A/C diode.
2. If battery voltage is present, turn ignition off. Check for continuity between terminals of A/C pressure switch. If continuity exists, go to next step. If continuity does not exist, check A/C system pressure. See «A/C SYSTEM PERFORMANCE»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual__ac-system-performance-test) under TESTING. If A/C system pressure is okay, replace A/C pressure switch. If A/C pressure is out of range, repair A/C system.
3. Reconnect A/C pressure switch connector. Disconnect A/C thermostat connector. Turn ignition on. Measure voltage between ground and Black/Yellow wire terminal of A/C thermostat connector. If battery voltage is not present, repair open Black/Yellow wire between underdash fuse/relay block and A/C thermostat. If battery voltage is present, measure voltage between ground and Yellow/White wire terminal of A/C thermostat connector.
4. If battery voltage is not present, repair open Yellow/White wire between A/C pressure switch and A/C thermostat. If battery voltage is present, turn ignition off. Reconnect A/C thermostat connector. Connect a jumper wire between ground and Blue/Red wire terminal of A/C thermostat connector (backprobe the terminal).
5. Start engine. If cooling fans do not come on and compressor clutch does not engage, replace A/C thermostat. If cooling fans come on and compressor clutch engages, turn ignition off. Disconnect jumper wire.
6. Remove heater control panel. Disconnect 14-pin connector. Turn ignition on. Measure voltage between ground and Blue/Red wire terminal of 14-pin connector. If battery voltage is not present, repair open Blue/Red wire between A/C thermostat and heater control panel. If battery voltage is present, turn ignition off.
7. Test A/C switch. See «A/C SWITCH»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual) under TESTING. If A/C switch is okay, disconnect blower switch 6-pin connector. Check for continuity in Green wire between heater fan switch and heater control panel. If continuity is not present, repair open Green wire between heater control panel and heater fan switch. If continuity is present, go to next step.
8. Check for continuity in Black wire between heater fan switch and ground. If continuity is present, replace heater fan switch. If continuity is not present, repair open Black wire between heater fan switch and ground. If Black wire is okay, check for poor ground connections.

TESTING

Note. For testing procedures not covered in this article, see HEATER SYSTEM article.

A/C SYSTEM PERFORMANCE TEST

1. Park vehicle out of direct sunlight. Open engine hood. Open front doors. Connect A/C pressure gauges to pressure ports. Determine relative humidity and ambient air temperature.
2. Move temperature control lever to coldest setting. Select vent mode. Select recirculated air. Insert a thermometer in center vent outlet. Set blower switch to highest speed. Run engine at 1500 RPM. Ensure no one is inside vehicle.
3. After running A/C for 10 minutes, check temperature at center vent outlet. Check system pressures. If temperature and pressures match the A/C system performance test chart, system is operating within range. (Scheme 4)or (Scheme 5).

Scheme 4

Scheme 5

A/C DIODE

Disconnect A/C diode connector, located behind right kick panel. There should be continuity between any combination of terminals (such as "B" and "C"), but only in one direction (polarity). (Scheme 6) If continuity is not as specified, replace A/C diode.

Scheme 6

Note. The A/C switch contains a diode, so check for continuity in both directions (both polarities).

Remove heater control panel. Disconnect 14-pin connector. With A/C switch on, check for continuity between terminals No. 11 (Blue/Red wire) and No. 12 (Green wire) of 14-pin connector. (Scheme 7) If there is no continuity, replace heater control panel.

Scheme 7

1. Remove A/C thermostat (requires removal and disassembly of evaporator case). Submerge sensing bulb in ice water. (Scheme 8) Connect 12 volts across terminals "C" (+) and "B" (-). Connect a 12-volt light bulb (rated from 3 watts to 18 watts) between terminals "A" and "C".
2. With temperature decreasing to 37°F (3°C) or less, light should be off. With temperature increasing to 39°F (4°C) or more, light should be on. If light does not respond as specified, replace A/C thermostat.

Scheme 8

COMPRESSOR CLUTCH

Measure resistance between ground and compressor clutch connector. If resistance is not 3.4-3.8 ohms at 68°F (20°C), replace compressor clutch. Use a feeler gauge to measure clearance between pulley and pressure plate. If clearance is not .014-.026" (.35-.65 mm), adjust clearance by adding or removing shims as necessary.

RELAYS

Remove relay. Ensure there is no continuity between terminals "A" and "C". (Scheme 9) With battery voltage applied across terminals "B" and "D", there should be continuity between terminals "A" and "C". Replace relay if it does not test as specified.

Scheme 9

REMOVAL & INSTALLATION

Note. For removal and installation procedures not covered in this article, see HEATER SYSTEM article.

COMPRESSOR

Note. If possible, before removing compressor, run engine at idle speed with A/C on for about 2 minutes.

Removal

Disconnect negative battery cable. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove power steering pump and set it aside (leave hoses connected). Disconnect condenser fan connector. Unplug compressor clutch connector. Remove condenser fan shroud. Disconnect suction and discharge hoses from compressor and plug openings. Remove compressor belt. Remove compressor mounting bolts and compressor.

Installation

To install, reverse removal procedure. If installing a new compressor, drain oil from old compressor into a measuring container. Subtract the volume of drained oil from 4.7 ounces. The result is the amount that you should drain from the new compressor. Tighten bolts to specification. See TORQUE SPECIFICATIONS . Evacuate and charge system.

1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Disconnect negative battery cable. Remove coolant reservoir and set it aside (leave hose connected). Remove upper radiator mounting brackets. Remove A/C hose bracket.
2. Disconnect A/C hoses from condenser and plug openings. Remove condenser bolts and condenser. To install, reverse removal procedure. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual) . Evacuate and charge system.

1. Disable air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Disconnect refrigerant lines from evaporator at engine compartment firewall and plug all openings.
2. Remove glove box and glove box frame. Disconnect A/C thermostat connector. (Scheme 10) Disconnect drain hose and remove evaporator case. Disassemble evaporator case. To install, reverse removal procedure. Tighten the bolts to proper specification. See «TORQUE SPECIFICATIONS»(/acura/integra/iii-1993-2001/remont/manual-hvac-system/#ac-heater-system-manual). Evacuate and charge system.

Scheme 10

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Manual A/C-Heater System Wiring Diagram. Scheme 11

See also:
• HEATER SYSTEM
• A/C SYSTEM PERFORMANCE TEST
• RELAYS
• A/C DIODE
• A/C SWITCH