A/c System General Servicing GMC Cab & Chassis R2500

COMPRESSOR OIL CHECK

Note. Only new, pure, moisture-free refrigeration oil should be used in the air conditioning system. This oil is highly refined and dehydrated (moisture content less than 10 parts per million). Refrigeration oil container must be kept tightly closed at all times when not in use, or moisture will be absorbed from the air and introduced into the refrigeration system.

GENERAL MOTORS

Note. Harrison Compressors, built by the Harrison Radiator Division of General Motors, may have been referred to in the past as Frigidaire, General Motors or Delco-Air Compressors.

HARRISON A-6 6-CYLINDER

The system is fully charged with 10 ounces of refrigeration oil. It will not normally require addition of oil unless definite oil loss has occurred due to ruptured line, leaking compressor seal, replacement of system component, compressor overhaul, or vehicle collision.

No Sign Of Oil Leakage

1. Remove compressor. Drain and measure oil. When replacing compressor, replace the amount drained plus one ounce. If the amount drained from compressor is over 8 ounces, system must be flushed. Replace accumulator and install compressor filled with 10 ounces total.
2. If evaporator is replaced, add 3 ounces to the new evaporator. If condenser is replaced, add one ounce. If accumulator is replaced, drain old accumulator and measure oil. Add the same amount, plus 2 ounces, to the new accumulator.

Signs Of Excessive Oil Leak

1. Remove compressor and accumulator. Drain and measure total oil from both components. If less than 6 ounces, add 6 ounces to the system. If more than 6 but less than 8 ounces, add the amount drained. If a new accumulator is installed, add 2 additional ounces to compensate for oil retained in the desiccant.
2. If amount drained is more than 8 ounces, flush system. Replace accumulator and install compressor filled with 10 ounces total.

Note. If oil drained contains metal chips or other foreign material, flush system. Replace expansion tube, accumulator, and other components as necessary.

HARRISON DA-6 6-CYLINDER

Systems with this compressor are fully charged with 8 ounces of refrigeration oil. Due to the compressor's design (without oil sump), the compressor does not have to be removed for oil measurement. Note the following situations for checking and adding oil with this system

No Sign Of Excessive Oil Leak

1. If compressor is replaced, remove, drain and measure oil. Replace with same amount of new oil plus one ounce. If evaporator is replaced, add 3 ounces of new oil. If condenser is replaced, add one ounce.
2. If accumulator is to be replaced, remove, drain oil, and measure. Replace with same amount of new oil, plus 3 ounces. If no oil can be drained from old accumulator, add 2 ounces of new oil.

Signs Of Excessive Oil Leakage

1. As the DA-6 compressor has no oil sump, the compressor retains a minimum of refrigeration oil. Therefore, only the accumulator needs to be removed, drained, and its oil measured.
2. If the amount recovered is less than 3 ounces, add 3 ounces of new oil to the system. If the amount is more than 3 ounces, add the same amount of new oil as that drained from the accumulator.

Note. If a new accumulator must be added to the DA-6 system, add an additional 3 ounces to compensate for that retained by the original accumulator desiccant.

HARRISON V5 5-CYLINDER

1. When a V5 compressor is removed from the vehicle for servicing, the amount of oil remaining in the compressor should be drained and measured. This oil should then be discarded and new refrigerant oil added. NOTE: Drain oil from the oil drain plug open to insure complete draining of oil from the compressor
2. The compressor has a unique lubrication system. The crankcase-suction bleed is routed through the rotating swashplate for lubrication of the swashplate bearing. The rotation acts as an oil separator, which removes some of the oil from the crankcase-suction bleed, re-routing it to the crankcase where it can lubricate the compressor mechanism.
3. Up to 4 ounces of oil can collect in the crankcase. All replacement compressors will be shipped from the factory with 8 ounces of oil in the crankcase. The oil must be drained from the oil drain plug opening and retained. Replace the oil in the same quantity as previously drained from the old compressor.

Note. If a new accumulator must be added to the V5 system, add an additional 2 ounces of oil to the compressor to compensate for that retained by the original accumulator desiccant.

HARRISON R-4 4-CYLINDER

Systems with this compressor are charged (new) with 6 ounces of refrigeration oil. Due to compressor's design (without oil sump), compressor does not have to be removed for oil measurement. Note the following situations for checking and adding oil with this compressor

1. If compressor is replaced, remove, drain and measure oil. Replace with same amount of new oil plus one ounce. If evaporator is replaced, add 3 ounces of new oil. If condenser is replaced, add one ounce.
2. If accumulator is to be replaced, remove, drain oil, and measure. Replace with same amount of new oil, plus 2 ounces to compensate for that retained by the original accumulator's desiccant.

Note. Also see Component Oil Replacement Quantities chart under "SERVICE SPECIFICATIONS" in this section.

Signs Of Excessive Oil Loss

If system has lost excessive oil, remove the accumulator, drain and measure oil. DO NOT remove or drain compressor. If more than 3 ounces is found in accumulator, add same amount of new oil as was drained. If less than 3 ounces is measured, add 3 ounces of new oil. If a new accumulator is being installed, add 2 additional ounces of oil to replacement accumulator.

Oil Charge Doubtful Or System Contaminated

If exact quantity of oil in system is in doubt or oil drained from components contains foreign particles, drain and flush system. Then, add a new charge of 6 ounces of refrigeration oil to system.

NIPPONDENSO 10-CYLINDER

To ensure that the Nippondenso 10-cylinder compressor has the proper amount of lubricating oil, discharge the system using approved refrigerant recovery/recycling equipment and remove the compressor. Remove the service valve assembly. Turn the compressor upside down and drain the oil from it. Once the oil has been drained, refill the compressor with 2.0-3.4 oz. of Densooil 6, Suniso No. 5GS or equivalent compressor oil.

REMOVAL & INSTALLATION

1. Discharge refrigerant from system using approved refrigerant recovery/recycling equipment and disconnect liquid line at evaporator inlet. Remove orifice disconnect liquid line at evaporator inlet. Remove orifice tube using needle nose pliers or orifice tube remover tool.
2. If difficulty is encountered during removal of a plugged or restricted orifice tube, remove as much impacted residue as possible. Using a heat gun, hair drier, epoxy drier or equivalent, carefully apply heat 1/4" from dimples on inlet pipe. Be careful not to overheat pipe. NOTE: If system has a pressure switch near orifice tube location, remove the switch prior to heating inlet pipe to avoid damaging switch.
3. While heat is being applied, install orifice tube extractor. Use a turning motion along with a push or pull motion to loosen orifice tube and remove it.
4. To install orifice tube, swab inside or inlet pipe with R-11. Add 1 oz. of refrigeration oil to system. Lubricate new orifice tube and refrigeration oil to system. Lubricate new orifice tube and O" ring with refrigeration oil and insert into inlet pipe. Install orifice tube with shorter screen end first.
5. Reverse the rest of removal procedure to complete installation. Recharge system and test system for proper operation.

BEFORE OPENING THE SYSTEM

Before disconnecting any lines or fittings, the system must be completely discharged using approved refrigerant recovery/recycling equipment.

DISCONNECTING LINES & FITTINGS

1. After system is discharged, carefully clean entire area around coupling nut to prevent dirt from entering system. Always use 2 wrenches to avoid twisting or distorting lines and fittings. Hold fitting with one wrench while loosening coupling nut with second wrench.
2. Immediately cap or plug all LINES and FITTINGS. DO NOT open lines. Remove caps only when connections are being made.

COMPONENT REPLACEMENT

When components are replaced, system oil level must be adjusted. Add refrigeration oil to replacement component. See Compressor Oil Check article, as well as, Component Oil Replacement Quantities chart under "SERVICE SPECIFICATIONS" in this section.

CONNECTING LINES & FITTINGS

1. A new "O" ring should be used in all instances when connecting lines and fittings (dip "O" ring in clean refrigeration oil and make certain it is not twisted during installation). Always use 2 wrenches to avoid twisting or distorting lines and fittings. Tighten coupling nuts securely.

PLACING SYSTEM IN OPERATION

After component replacement and/or system servicing has been completed and all connections have been made, proceed as follows

1. Evacuate system using vacuum pump.
2. Charge system with R-12. See REFRIGERANT CAPACITY in this section.
3. Leak test system. Give particular attention to all new connections and components.
4. Perform performance test of system. Never assume recharging has automatically corrected a problem.

DIAGNOSTIC PROCEDURES

Diagnosis is an important first step in A/C system servicing. To save time and effort, systems should be carefully checked to identify the causes of poor performance. By using the following diagnostic charts, defective components or system damage can be quickly located. To identify problems that are specific to one system, refer to the repair section of this manual. The charts in this section apply to all systems.

ALTITUDE PRESSURE VARIATIONS

ALTITUDE VACUUM VARIATIONS

PREPARATION FOR TESTING

1. Attach Low and High side gauges.
2. Start engine and allow it to warm up.
3. Set system to COOL and blower to HIGH.
4. Open car doors and hood.
5. Run at fast idle for 2-3 minutes.

OPERATIONAL TEST GAUGE READINGS

NORMAL SYSTEM OPERATING PRESSURES (PSI) (1)

AIR CONDITIONING SYSTEM PERFORMANCE CHECK. Scheme 34

AMBIENT TEMPERATURE/PRESSURE. Scheme 35

EVAPORATOR TEMPERATURE/PRESSURE. Scheme 36

AIR CONDITIONING DIAGNOSIS WITH GAUGES FOR SYSTEMS WITH INSUFFICIENT OR NO COOLING

SPECIFICATIONS

SYSTEM REFRIGERANT CAPACITIES

COMPRESSOR OIL REPLACEMENT QUANTITIES

COMPONENT OIL REPLACEMENT QUANTITIES

COMPRESSOR BELT TENSION (Lbs.) (1)

COOLING SYSTEM CAPACITIES (1) (CHEVROLET & GMC)