MODEL IDENTIFICATION
Adjustment and repair procedures in this article are referred to by series. The following table lists General Motors model name and series designation.
GENERAL MOTORS MODEL DESIGNATION
| Model | Designation | |
|---|---|---|
| Blazer, Bravada, Jimmy | ||
| Pickup & Sonoma | "S" & "T" Series | |
GENERAL MOTORS MODEL DESIGNATION
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 | ||
| "S" & "T" Series | Harrison R-4 4-Cyl. Harrison V5 5-Cyl. | |
| Compressor Belt Tension | (1) | |
| Compressor Oil Capacity | 2 oz. | |
| Refrigerant (R-12) Capacity | ||
| "S" & "T" Series | 40 oz. | |
| System Operating Pressures | (2) | |
| (1) Tighten serpentine belt until indicator mark on movable portion of belt tensioner is within limits of slotted area on stationary portion of belt tensioner. (2) Information not available from manufacturer. | ||
| (1) | Tighten serpentine belt until indicator mark on movable portion of belt tensioner is within limits of slotted area on stationary portion of belt tensioner. |
| (2) | Information not available from manufacturer. |
A/C SYSTEM SPECIFICATIONS
SYSTEM DESCRIPTION
Integral A/C-heater system is a blend-air system. Air entering the vehicle must pass through evaporator core and through, or around, heater core to provide air of the desired temperature. Compressor operation is controlled by a pressure cycling switch on top of the accumulator.
MODE CONTROL LEVER OPERATION
Mode 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.
LOW REFRIGERANT DETECTION
The controller monitors the state of the low pressure cycling switch, if the compressor has been activated and measures the duration of the compressor "ON" time.
The minimum compressor "ON" time limit will be 1.5 seconds. Once this limit (less than 1.5 seconds) has been exceeded for 10 consecutive cycles the compressor will be turned off and remain off until the servicing has been performed and the battery disconnected to reset the memory.
The A/C indicator shall flash for a period of 2 minutes and then turn "OFF" when the low charge condition has been detected. It shall also flash at every ignition cycle for 2 minutes until the servicing has been performed and the battery disconnected to reset the memory.
TEMPERATURE CONTROL LEVER OPERATION
Temperature control lever regulates the temperature of air entering passenger compartment through a cable-operated blend-air door. In COLD position, air by-passes the heater core to provide maximum cooling.
In other positions, air chilled by the evaporator core and heated air from the heater core are mixed to provide air of the desired temperature. In HOT position, A/C system should be off to provide maximum heating.
BLOWER SWITCH OPERATION
Blower switch is a 4-position switch with LOW, HI and 2 intermediate positions. Blower operates in any mode control lever position except OFF.
TEMP CONTROL CABLE ADJUSTMENT
Remove complete glove box. Disengage temperature cable retaining clip from lever. Bend the cable (to shorten or lengthen) and reattach. Move temperature selector lever the full range of travel in both directions. A thud should be heard at blend-air door open and closed positions. If thud is not heard, bend cable and try again.
TROUBLE SHOOTING
See appropriate TROUBLE SHOOTING article in this section.
Removal
- Disconnect battery ground cable and compressor clutch connector. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect accumulator inlet and outlet lines and cap or plug openings.
- Remove accumulator bracket screws and remove accumulator from vehicle. Drain refrigerant oil from accumulator and measure quantity drained.
Installation
- Measure an amount of clean refrigerant oil equal to that drained from accumulator and add an additional 2 ounces. Uncap new accumulator and add oil.
- To complete installation, reverse removal procedure. Use new "O" rings lubricated with clean refrigerant oil. Leak test, evacuate and recharge system.
Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect liquid line from the evaporator inlet. Cap opening on line. Using needle-nose pliers, remove orifice tube from evaporator core inlet line.
To install, reverse removal procedure. Use new "O" rings lubricated with clean refrigerant oil. Insert short screen end of orifice tube first. (Scheme 15) Leak test, evacuate and recharge system.
Scheme 15
EXPANSION VALVE R & I
Note. Expansion valve is used on auxiliary units that do not use external equalizer line.
Removal & Installation
- Disconnect battery ground cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove blower motor resistor screws and lay resistor aside with wires attached. Remove air cleaner attaching screws and lay air cleaner aside. Remove 5 screws and 2 nuts at case. Disconnect connector at A/C harness. Separate case halves and remove evaporator core cover.
- Disconnect liquid line and evaporator-to-accumulator line. Remove screw attaching evaporator line bracket to accumulator bracket. Remove evaporator core including orifice tube from vehicle. To install, reverse removal procedure. Use new "O" rings lubricated with clean refrigerant oil. Leak test, evacuate and recharge system.
Disconnect negative battery cable. Disconnect electrical connector at blower motor. Remove blower motor screws, and remove blower motor. (Scheme 16) To install, reverse removal procedure.
Scheme 16
- Disconnect negative battery cable. Remove screws from bottom of control panel. Pull control assembly away from instrument panel. (Scheme 17)
- Disconnect control cables and blower switch electrical connectors. Remove control assembly. Remove blower switch knob and retaining clip, and remove blower switch. To install, reverse removal procedure.
Scheme 17
HEATER CORE R & I
| CAUTION | Heater core can be damaged if too much force is applied to heater core pipes during hose removal. |
Note. To make the removal of the rear case cover easier, remove all the I/P lower screws and loosen the upper screws and pull out on the I/P at the right lower side to gain additional clearance.
- Disconnect the negative battery cable. Drain engine coolant. Remove heater hoses at core. Remove case (rear) screws. Remove case (rear). (Scheme 18) Remove the 2 heater core retaining straps and remove the heater core.
- To install, reverse removal procedure. (Scheme 18)- (Scheme 20). Fill cooling system, and check for leaks.
Scheme 18
Scheme 19
Scheme 20
Disconnect negative battery cable. Pull control assembly from dash. (Scheme 21) Disconnect cables at control assembly and heater assembly. Remove cables. To install, reverse removal procedure.
