A/c-Heater System - Manual Chevrolet Camaro III рестайлинг

MODEL IDENTIFICATION

Adjustment and repair procedures in this article are referred to by either model or body type. The following table lists General Motors division, model name and body type.

GENERAL MOTORS MODELS

DESCRIPTION

For 1988 2 different air conditioning systems are available on all. These systems are the V-5 A/C system, which uses a variable displacement compressor and the Cycling Clutch Orifice Tube (CCOT) system.

The CCOT system uses a fixed orifice tube to meter the flow of refrigerant into the evaporator. A pressure cycling (sensing) switch cycles the compressor on and off to maintain the desired cooling and to prevent evaporator freeze-up.

A pressure cycling switch is not used with V-5 compressor A/C systems. This compressor can vary its displacement to match A/C demands under all conditions.

All models use a 4-cylinder radial, 5-cylinder (V-5) or 6-cylinder axial compressor depending on engine and body style.

UNCONDITIONED AIR

Air, either outside or recirculated, enters the system and is drawn through the evaporator core. There it receives maximum cooling if system controls are set for cooling mode of operation.

After leaving the evaporator, the air is forced by the blower into the heater and A/C selector duct assembly.

Depending on position of the temperature control door, air passes either through or around the heater core, in proper proportions to obtain the desired discharge air temperature.

CONDITIONED AIR

Discharge air may be directed to either the floor and defroster outlets or to the dash registers by a cable-actuated or vacuum-actuated diverter door. If the air is not directed to the dash outlets, another cable-actuated or vacuum-operated door directs airflow to either the floor outlets or the defroster outlets.

During cooling modes of operation, air may be cooled below the comfort level. If this happens, air can be warmed by the heater core to arrive at the desired temperature by adjusting the temperature control lever.

MODE SELECTOR LEVER/DIAL

Note. Several models are equipped with push button controls instead of a selector lever. The following descriptions apply equally to push button systems when the indicated setting is chosen.

Several settings are possible on control panel to provide the comfort level desired. Upper lever is mode selector. On push button control models, push buttons replace this lever. (Scheme 21)and (Scheme 22).

On dial selector types, rotating dial from left to right selects mode function for these types. Available mode settings are as follows

OFF

No blower operation occurs in this position. No air conditioning takes place.

Typical GM Man. A/C Control Panel W/Mode Selector Lever Some also have defroster button. Scheme 21

Typical GM Man. A/C Control Panel W/Push Button Mode Select. Scheme 22

MAX

Maximum cooling is provided in this setting. Conditioned air is distributed through dash registers, with a slight amount to the floor at any blower speed.

NORM

Conditioned air is directed through dash registers, with a slight amount directed to floor.

BI-LEVEL

Conditioned air is directed through dash registers and floor outlets, with some also to windshield.

VENT

In this position the compressor is not operating. Outside air is delivered through dash registers.

Compressor does not operate in this position. Outside air is heated and distributed; about 80% to floor and 20% to windshield and side windows.

DEFROST

In this position, conditioned air is distributed; about 80% to windshield and side windows and 20% to floor.

Typical Heater-A/C Module. Scheme 23

TEMPERATURE LEVER/DIAL

When temperature lever/dial is placed in "COLD" or "C" position, no airflow is allowed through the heater core. If the lever is placed in "HOT" or "H" position, all air flows through the heater core.

COMPONENTS & FUNCTIONS

Note. Not all components are used on all models.

PRESSURE CYCLING SWITCH

Located near the top of the accumulator, this switch cycles the compressor on at 46 psi and off at 25 psi. Switch also turns off compressor in event of low refrigerant charge or cold (below 37°F) ambient temperatures.

PRESSURE RELIEF VALVE

Pressure relief valve is located on the rear of the compressor. It opens automatically when the discharge side pressure reaches approximately 440 psi. This prevents damage due to excessive pressure.

ACCUMULATOR

The accumulator is a refrigerant storing device, located at the evaporator outlet. This unit receives and stores vapor, some liquid and refrigerant oil from the evaporator.

An oil bleed hole is located in the lower portion of the accumulator, assuring return of the oil to the compressor. This prevents oil from being trapped in the accumulator. A bag of desiccant is located in the bottom of the accumulator. (Scheme 24)

Manual A/C-Heater System Accumulator Assembly. Scheme 24

ORIFICE TUBE

The orifice tube is located in the evaporator inlet or in condenser outlet. It controls the flow of liquid refrigerant into the evaporator. The orifice tube replaces the previously used expansion valve.

The tube has no moving parts and is not adjustable. If plugged or defective, it must be replaced as a unit. (Scheme 25)

CCOT System Orifice Tube. Scheme 25

WIDE-OPEN THROTTLE CUT-OUT SWITCH

Wide-open throttle cut-out switch, located on the carburetor or accelerator pedal bracket, is used to improve acceleration by stopping compressor operation under full load.

On models with TBI or EFI, the Throttle Position Sensor (TPS) sends a signal to the Electronic Control Module (ECM) which then regulates the compressor.

POWER STEERING CUT-OFF SWITCH

The power steering cut-off switch stops compressor operation when power steering pressure exceeds a preset level. This reduction in engine load prevents stalling during parking.

COMPRESSOR (HIGH PRESSURE) CUT-OFF SWITCH

The high pressure switch stops compressor operation if high side pressure exceeds 410-450 psi. This prevents compressor damage and loss of refrigerant. After pressure drops below 150-250 psi, compressor operation resumes.

LOW PRESSURE CUT-OFF SWITCH

Compressor protection is offered by a low pressure cut-off switch that opens in response to a low refrigerant charge.

A/C TIME DELAY RELAY

This relay prevents the compressor from operating for 10 seconds after the engine is started or A/C mode is selected.

If system is operating, current is applied to idle stop solenoid of automatic transmission models to increase engine idle speed. It also stops the compressor if engine temperature light comes on due to overheating.

COMPRESSOR CONTROL RELAY

Under certain operating conditions, compressor operation may be cut off by A/C control relays, wide-open throttle, low air temperature, low engine speed and/or high coolant temperature.

CONSTANT RUN RELAY

On models so equipped, engine idle quality is maintained by this relay. It eliminates compressor cycling during engine idle for a pre-determined time after vehicle has come to rest from road speed. Relay is controlled by ECM and engine sensors.

TEMPERATURE CUT-OFF RELAY

The temperature cut-off relay is operated by a temperature switch in the coolant system. If engine temperature rises to an excessive level, the switch opens. This cuts power to the relay, interrupting compressor operation.

AIR TEMPERATURE SENSOR

The function of the air temperature sensor is to prevent compressor operation when ambient air temperature falls below a specific level.

TEMPERATURE CONTROL CABLE

1. Control cable is self-adjusting. However, an initial setting should be made to allow for correct adjustment. Disengage temperature cable retaining clip from bellcrank post. Position threaded operating rod so that it extends 3/8" beyond outer edge of White nylon retaining button.
2. Reassemble temperature cable retaining clip to bellcrank vertical post. Move lever through full range of operation (full "HOT" to full "COLD" ) to automatically adjust cable. Temperature door thud should be heard at both ends of lever movement.

TROUBLE SHOOTING

Note. Refer to A/C SYSTEM DIAGNOSIS - MANUAL article in this section.

Removal & Installation

When removing high pressure switch, system must be dis- charged. All other switches are on Schrader-type valves and do not require discharging of system to remove.

Removal

1. Disconnect negative battery cable. Disconnect compressor clutch coil wire. Remove cooling fan and fan shroud (if required).
2. Discharge A/C system using approved refrigerant recovery/recycling equipment. remove fitting block and hose assembly from rear of compressor. Remove mounting bracket bolts and brackets. Remove drive belt from compressor.
3. Remove compressor. On models equipped with V-5 compressor, remove crankcase drain plug from bottom of compressor. Drain oil from crankcase and also from suction and discharge ports. On all other models, drain oil from suction and discharge ports. On all models measure amount of oil drained and record. Discard old oil.

Installation

Add clean refrigerant oil in same amount that was drained. Reverse removal procedure to install. Use new "O" rings lubricated with clean refrigerant oil. DO NOT soak "O" rings as this will cause them to expand. Evacuate and recharge system.

Disconnect battery ground cable. Remove trim plate. Remove mounting screws. Pull control head out and disconnect vacuum lines, electrical connections and control cable. Remove control head. Reverse removal procedure to install. Insert lower right side retaining screw first to align control head in console.

1. Disconnect negative battery cable and discharge system using approved refrigerant recovery/recycling equipment. Disconnect accumulator inlet and outlet lines. Disconnect all electrical connections. Remove pressure cycling switch (if equipped).
2. On all models, loosen or remove accumulator mounting bracket bolts and remove accumulator (with or without bracket as needed). Check amount of refrigerant oil in old accumulator.
3. On all models, add this amount plus 2 ounces. Reverse removal procedure to install. Use new "O" rings lubricated with clean refrigerant oil. DO NOT soak "O" rings as this will cause them to expand. Evacuate and recharge system.

Locate blower resistor on evaporator case. Disconnect battery ground cable and resistor wiring harness connector. Remove 2 resistor mounting screws. Remove resistor. Reverse removal procedure to install.

Typical Condenser Location & Installation. Scheme 26

1. Discharge refrigerant system using approved refrigerant recovery/recycling equipment. Remove accumulator. Remove 2 high blower relay terminal attaching screws and remove terminal. Remove upper case screws, relocate wiring harness and remove dipstick.
2. Disconnect liquid line fitting. Remove upper case and lift evaporator core out of case (retaining foam wedge). Reverse removal procedure to install.

1. Drain cooling system. Remove heater hoses from heater core. Remove right side lower hush panel and right-hand lower trim of instrument panel. Remove lower right side instrument carrier-to-cowl screw.
2. Remove 4 heater case cover screws. (Scheme 27) Upper left side screw is reached using a long socket extension through panel opening. Lift corner of instrument panel slightly to align socket. Remove heater case cover.
3. Remove core support plate and baffle screws. Remove heater core, support plate and baffle. Reverse removal procedure to install. Seal any air leaks and check for coolant leakage.

Heater Case and Core Assembly Camaro and Firebird models shown. Scheme 27

1. Discharge refrigerant system using approved refrigerant recovery/recycling equipment. Disconnect condenser-to-evaporator line at evaporator inlet or line at condenser. Using special tube removal tool or needle nose pliers, remove orifice tube and "O" ring from line.
2. If removal of orifice tube is difficult, remove as much of impacted residue as possible. Using a heat gun or hair drier, apply heat 1/4" from dimples on inlet pipe. Do not overheat pipe. NOTE: If vehicle is equipped with a pressure switch (mounted near orifice tube location), it should be removed when heating inlet tube to prevent damage to switch.
3. Reverse removal procedure to install tube. If residue resulted in difficult tube removal, add 1 ounce of refrigerant to system before installing tube. Use new "O" ring coated with refrigerant oil. DO NOT soak "O" ring as this will cause it to expand. Install short screen end of orifice tube first. Evacuate and charge system.

1. The fitting on the accumulator is equipped with a Schrader-type valve, making system discharge unnecessary. Disconnect battery ground cable and wires at switch.
2. Unscrew switch from accumulator. When installing switch, use a new "O" ring lubricated with clean refrigerant oil. DO NOT soak "O" ring as this will cause it to expand. Do not overtighten.

Camaro & Firebird A/C Vacuum Diagram. Scheme 28

Camaro & Firebird Manual A/C-Heater Wiring Diagram. Scheme 29

See also:
• A/C SYSTEM DIAGNOSIS - MANUAL