A/c-Heater System Chevrolet Astro I

DESCRIPTION

A/C-heater system is a blend-air system. Air entering vehicle must pass through evaporator core and through, or around, heater core to provide air of desired temperature. Compressor operation is controlled by a pressure cycling switch on top of accumulator.

An auxiliary A/C system is available. The system operates in conjunction with main system, and provides air conditioning only. Auxiliary heater is a separate unit. Auxiliary blower motor switches are independent of main system control. Rear blower motor may be operated even when front blower motor is off.

OPERATION

Blower Switch Lever

Blower switch is a 5-position lever with OFF, low, HIGH and 2 intermediate positions. (Scheme 1) Blower motor operates in any position except OFF. Auxiliary A/C-heater blower switches are 4-position levers. (Scheme 2)

Mode Selector Lever

Mode selector lever controls a vacuum-operated selector valve to operate air door motors, providing desired air distribution. It also allows for selection of air conditioning or heating functions, including defroster air distribution. (Scheme 1)

Temperature Control Lever

Temperature control lever regulates temperature of air entering passenger compartment through a cable-operated blend-air door. In cold position, air by-passes heater core to provide maximum cooling. (Scheme 1)

In other positions, cooled air from evaporator core and heated air from heater core are mixed to provide air of desired temperature. In hot position, A/C system should be off to provide maximum heating.

Scheme 1

AUXILIARY BLOWER SWITCH

Auxiliary blower switches (A/C and heater) are located above radio. Switches control auxiliary A/C-heater system. In OFF position, blower motor is inoperative, even though refrigerant is circulating through evaporator core when main system is operating. To operate auxiliary system, simply select desired blower speed (LO, MED or HI position). (Scheme 2) Auxiliary blower motor may be used for air circulation when main system is not in A/C mode.

Scheme 2

TROUBLE SHOOTING

Note. For Trouble Shooting information not covered in this article, refer to the HEATER SYSTEM article in the AIR CONDITIONING & HEAT section.

Note. Before performing trouble shooting procedures, ensure A/C-heater fuse is not blown.

A/C COMPRESSOR INOPERATIVE

Note. Outside temperature must be more than 60°F (16°C) in order to properly diagnose system.

1. Turn ignition on. Set mode selector lever in NORM A/C position. Connect test light between Brown/White wire at mode selector control connector and ground. If test light glows, go to next step. If test light does not glow, repair open Brown/White wire between mode selector control and fuse block.
2. Connect test light between Light Green wire at low pressure cycling switch connector (located on A/C accumulator) and ground. Cycle mode selector lever through all A/C positions. If test light glows in all positions, go to next step. If test light does not glow in all positions, check Light Green wire between low pressure cycling switch connector and mode selector control. Repair if necessary. If wire is okay, replace mode selector control.
3. Disconnect low pressure cycling switch connector. Set mode selector lever in any A/C position. Connect a jumper wire between Light Green wire and Dark Blue wire at low pressure cycling switch connector. Connect test light between Dark Blue wire at high pressure cycling switch connector and ground. If test light glows, go to next step. If test light does not glow, repair open Dark Blue wire between low pressure cycling switch connector and high pressure cycling switch connector.
4. Disconnect high pressure cycling switch connector. Connect a jumper wire between Dark Green wire and Dark Blue wire at high pressure cycling switch connector. Connect test light between Dark Green wire at A/C compressor clutch connector and ground. If test light glows, replace A/C compressor. If test light does not glow, repair open Dark Green wire between high pressure cycling switch connector and A/C compressor clutch connector.
5. Using a DVOM, check continuity between Black wire at A/C compressor clutch connector and ground. If continuity exists, replace A/C compressor clutch. If continuity does not exist, repair open Black wire between A/C compressor clutch and ground.

AUXILIARY BLOWER MOTOR INOPERATIVE

1. Disconnect auxiliary A/C-heater blower motor connector (located behind left rear wheelwell). Connect a test light between Brown wire at blower motor connector and ground. If test light glows, go to next step. If test light does not glow, repair open Brown wire between blower motor connector and fuse block.
2. Using a DVOM, check continuity between Black wire at auxiliary blower switch connector and ground. If continuity exists, go to next step. If continuity does not exist, repair open Black wire between auxiliary A/C-heater blower switch connector and convenience center (located behind left side of instrument panel).
3. Set auxiliary A/C-heater blower switch in LO, MED or HI position. Connect self-powered test light between appropriate wire at auxiliary A/C-heater blower switch connector (depending on switch position) and ground. LO position is Yellow wire, MED position is Light Blue wire, and HI position is Orange wire. If test light glows, repair appropriate open wire(s) to auxiliary A/C-heater blower motor. If test light does not glow, replace auxiliary A/C-heater blower switch.

AUXILIARY BLOWER MOTOR OPERATES IN HIGH SPEED ONLY

1. Set auxiliary A/C-heater blower switch in inoperative position. Using a DVOM, check continuity between appropriate wire at auxiliary A/C-heater blower switch connector (depending on switch position) and ground. LO position is Yellow wire, and MED position is Light Blue wire. If continuity exists, go to next step. If continuity does not exist, replace auxiliary A/C-heater blower switch.
2. Check for continuity between appropriate wire at auxiliary A/C-heater blower motor (depending on switch position) and ground. If continuity does not exist, repair open Yellow wire or Light Blue wire between blower switch connector and auxiliary A/C-heater blower motor connector. If continuity exists, replace auxiliary A/C-heater blower motor.

AUXILIARY BLOWER MOTOR OPERATES IN LOW &/OR MEDIUM SPEED ONLY

Connect test light between Orange wire at auxiliary A/C-heater blower switch connector and ground. If test light glows, repair open Orange wire between auxiliary A/C-heater blower motor connector and auxiliary A/C-heater blower switch. If test light does not glow, replace auxiliary A/C-heater blower switch.

BLOWER MOTOR INOPERATIVE

1. Turn ignition on. Set blower switch in HIGH position. Connect test light between Brown wire at blower switch connector and ground. If test light glows, go to next step. If test light does not glow, repair open Brown wire between blower switch connector and fuse block.
2. Connect test light between Orange wire at blower switch connector and ground. If test light glows, go to next step. If test light does not glow, replace blower switch.
3. Connect test light between Purple wire at blower motor connector and ground. If test light glows, go to next step. If test light does not glow, repair open Purple wire between blower motor connector and high blower relay connector.
4. Connect test light between Purple wire and Black wire at blower motor connector. If test light glows, replace blower motor. If test light does not glow, repair open Black wire between blower motor connector and ground.

BLOWER MOTOR DOES NOT OPERATE IN HIGH SPEED

1. Turn ignition on. Set blower switch in HIGH position. Connect test light between Orange wire at blower switch connector and ground. If test light glows, go to next step. If test light does not glow, replace blower switch.
2. Connect test light between Orange wire at high blower relay connector (located on bracket at right side of cowl) and ground. If test light glows, go to next step. If test light does not glow, repair open Orange wire between blower switch connector and high blower relay connector.
3. Connect a test light between Black wire at high blower relay connector and ground. If test light glows, go to next step. If test light does not glow, repair open Black wire between high blower relay connector and ground.
4. Connect test light between Red wire at high blower relay connector and ground. If test light glows, replace high blower relay. If test light does not glow, repair fusible link or open Red wire between high blower relay connector and battery junction block.

BLOWER MOTOR OPERATES IN HIGH SPEED ONLY

1. Turn ignition on. Set blower switch to medium-low position (detent next to low) or medium-high position (detent next to high position). Connect test light between Dark Blue wire at blower resistor connector (located on blower motor housing) and ground. If test light glows, go to step 3).
2. If test light does not glow, check open Light Blue wire and/or Tan wire between blower resistor connector and blower switch connector. Repair if necessary. If wires are okay, replace blower resistor.
3. Connect test light between Dark Blue wire at high blower relay connector (located at right side of cowl on bracket) and ground. If test light glows, replace high blower relay. If test light does not glow, repair open Dark Blue wire between blower resistor connector and high blower relay connector.

TESTING

A/C SYSTEM PERFORMANCE

1. Park vehicle out of direct sunlight. Open windows or door to ventilate interior. Vent engine exhaust, if necessary. Install manifold gauge set. Note ambient temperature and humidity.
2. Close all windows and doors. Place mode selector lever in NORM A/C position, blower switch lever in HIGH position, and temperature control lever in full cold position.
3. Insert A/C Diagnostic Tester (J 21213-A) into right center vent. Place transmission in Park or Neutral. Start engine and allow it to run at 2000 RPM until temperature tester reaches lowest temperature (approximately 3 minutes). See A/C SYSTEM SPECIFICATIONS table.

A/C SYSTEM SPECIFICATIONS

REMOVAL & INSTALLATION

Note. For removal and installation procedures of auxiliary heater system components, see the HEATER SYSTEM article in the AIR CONDITIONING & HEAT section.

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect electrical connections (if necessary). Disconnect accumulator inlet and outlet lines, and plug openings. Remove accumulator bracket screws. Remove accumulator from vehicle.
2. Add 3.5 ounces of clean refrigerant oil to new accumulator prior to installation. To complete installation, reverse removal procedure. Lubricate new "O" rings with clean refrigerant oil prior to installation. Evacuate, recharge and leak test system.

Disconnect negative battery cable. Remove storage compartment from rear door. Remove door cover. Remove electrical connections. Remove cooling tube from blower motor. Remove screws securing blower motor. Remove blower motor. (Scheme 3) To install, reverse removal procedure.

Scheme 3

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove rear ducts. Disconnect electrical connections.
2. Remove evaporator tube. Disconnect refrigerant lines at rear of evaporator/blower assembly, and cap openings. Remove screws and evaporator/blower assembly. Separate case halves, and remove evaporator core.
3. To install, reverse removal procedure. Lubricate new "O" rings with clean refrigerant oil prior to installation. Add 3 ounces of clean refrigerant oil to new evaporator core. Evacuate, recharge and leak test system.

1. Disconnect negative battery cable. Disconnect blower motor electrical connections. Remove coolant recovery tank. Remove bolts from windshield washer reservoir, and secure aside.
2. Disconnect blower motor cooling tube. Remove blower motor-to-case screws. Remove blower motor. Remove blower fan-to-blower motor shaft nut. Remove fan. To install, reverse removal procedure. (Scheme 4)

Scheme 4

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove electrical connections if necessary. Remove engine cover.
2. Remove drive belt and oil filler tube. Remove refrigerant hoses from compressor, and cap openings. Remove compressor brace and compressor.
3. To install, reverse removal procedure. Drain and measure oil from old compressor. If less than one ounce is drained, add 2 ounces of refrigerant oil to new compressor. If more than one ounce is drained, add the same amount to new compressor. Evacuate, recharge and leak test system.

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove grille and front panel. Remove radiator tie bar support at top. Disconnect inlet and outlet lines at condenser, and cap openings. Remove condenser bolts. Remove condenser from vehicle.
2. To install, reverse removal procedure. Lubricate new "O" rings with clean refrigerant oil prior to installation. Add one ounce of clean refrigerant oil to condenser. Evacuate, recharge and leak test system.

Disconnect negative battery cable. Remove instrument panel center bezel. Remove control panel screws. Remove control cable, and disconnect vacuum and electrical connectors at control panel. Remove control panel. To install, reverse removal procedure.

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Drain engine coolant. Remove coolant recovery tank. Remove wiper/washer fluid tank. Disconnect electrical connections.
2. Remove heater core hoses. Remove accumulator suction hose. Remove evaporator connector at accumulator. Remove accumulator from evaporator. Remove relay bracket located above evaporator. Remove case flange nuts and bolts. Separate case halves, and remove evaporator core. (Scheme 4)
3. To install, reverse removal procedure. Lubricate new "O" rings with clean refrigerant oil prior to installation. Add 3 ounces of clean refrigerant oil to new evaporator prior to installation. Fill cooling system and check for leaks. Evacuate, recharge and leak test A/C system.

HEATER CORE

Disconnect negative battery cable. Drain engine coolant. Remove heater hoses at core. Remove lower distributor duct. Remove defrost outlet duct. Remove heater case cover screws. Remove heater core. To install, reverse removal procedure. Fill cooling system and check for leaks.

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect inlet line from evaporator inlet and cap opening. Using needle-nose pliers or orifice tube remover, remove orifice tube from evaporator core inlet line. CAUTION: If vehicle is equipped with a pressure switch mounted near orifice tube location, remove switch before heating inlet tube to prevent damage to switch.
2. If removal of orifice tube is difficult, remove as much of impacted residue as possible. Using a heat gun or hair dryer, apply heat 1/4" from dimples on inlet pipe. DO NOT overheat pipe.
3. To install, reverse removal procedure. Lubricate new "O" ring with clean refrigerant oil prior to installation. DO NOT soak "O" ring, as this will cause it to expand. Insert short screen end of orifice tube first. (Scheme 5) Evacuate, recharge and leak test system.

Scheme 5

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 6