Air Conditioning Compressor Replacement Procedure

EQUIPMENT REQUIRED:
SAFETY PRECAUTIONS:

^ Wear goggles and gloves. Refrigerant boils at -22~F., so it can cause severe frostbite if it comes into contact with your hands or eyes.

^ Do not expose a container of refrigerant to direct sunlight or to temperatures higher than 120~F. The heat can cause dangerous pressure to build up in the container. Also, use caution during handling to avoid accidental dropping of the container.

^ Do not expose refrigerant to flame or hot metal. When heated, R12 forms phosgene gas, which is highly toxic. It can cause convulsions and death.
CAUTION: Work in well ventilated area. Refrigerant gas can displace the oxygen in your lungs.

PROCEDURE:

Discharging the System:

1. Make sure both valves on your manifold gauge set are closed.

2. Attach the high side manifold nose to the high side service port on the vehicle.

3. Attach the low side manifold hose to the low side service port on the vehicle.

4. Connect the center manifold hose to a clean, empty purge container. Do not discharge into shop towel.

5. Open the high side manifold valve slowly and adjust the discharge flow rate so that little or no oil is being carried out of the system and into the purge container.

6. When the high side gauge reading has dropped below 50 psi or it is equal to the low side gauge reading, slowly open the low side manifold valve.

7. When all system pressure is exhausted, close both the high and low side manifold valves.

8. Using a clean, graduated container, measure the amount of oil that was discharged from the system into the purge container. Write down the amount for reference.

Changing the Compressor:

1. Clean any dirt or foreign material away from the A/C compressor line flanges.

2. Disconnect the low and high pressure lines from the compressor. Install blind plugs on the lines as soon as they are disconnected.

3. Remove the compressor from its bracket.

4. Using a clean, graduated container, drain and measure all oil from the removed compressor. Write down this amount for reference.

5. Remove the caps from the new, countermeasure compressor and drain all compressor oil into a clean, graduated container.

6. Pour back into the new, countermeasure compressor the exact amount of clean compressor oil that was removed from the system during discharge, plus the amount taken from the removed compressor. CAUTION: Use only the clean oil that was drained from the new compressor. Use a clean container to hold the oil and to pour from. Re-install the caps on the new compressor.



7. Install the new compressor on the vehicle compressor bracket. Torque the compressor-to-bracket mounting bolts as shown in the chart below.



8. Check the compressor drive belt for any damage. Replace if necessary. Install the compressor drive belt and adjust the belt tension according to the specifications given in the chart below.



Applied Force: 98 N. (10 kg., 22 lb.)
9. Remove the caps from the compressor and the blind plugs from the high and low pressure lines. Coat new O-rings with clean compressor oil and install them.



10. Install high and low pressure lines on the compressor. Torque the flange bolts/nuts according to the following chart:
Evacuating the System:

1. The manifold gauge set should still be connected at the high and low pressure ports. Make sure all valves are closed on the manifold gauge set.

2. Connect the center manifold gauge line to the vacuum pump.

3. Turn on the vacuum pump.

4. Slowly open the low side and high side manifold valves.

5. Evacuate the system, maintaining a vacuum level of 29.92 in. Hg. (760 mm Hg) or more for a minimum of 20 minutes.

NOTE: The gauge will read 1 in. Hg. less for every 1,000 feet of elevation above sea level.

6. Close the high side manifold valve. Then close the low side manifold valve.

7. Turn off the vacuum pump. Note the low side gauge reading.

8. Wait 5 minutes and check the low side gauge reading. If it has changed more than 1 in. Hg., the system must be checked for a leak. If the low side gauge reading has not changed more than 1 in. Hg., you may charge the system with refrigerant.


Charging the System:

1. Disconnect the center manifold hose from the vacuum pump and connect the hose to the 30 lb. refrigerant container. Place the refrigerant container on a scale and record its weight.

2. Open the valve at the refrigerant container.

3. Make sure you are wearing goggles and gloves. Very slowly, loosen the center hose connection at the manifold and allow R12 to escape for 2 seconds. Then re-tighten the hose fitting at the manifold.
4. WITH THE ENGINE OFF: slowly open the high side manifold valve.
CAUTION: Do not start the engine during this operation. You could cause a dangerous pressure back-up into the refrigerant canister. Do not open the low side valve at this time. A charge of liquid refrigerant into the low side could cause a hydraulic lock in the compressor.





















5. When the high and low side gauge readings are about equal, or when the system has taken the correct amount of refrigerant (see specification chart below), close the high side manifold valve.
6A. If the system has taken the specified amount of refrigerant, turn the compressor several times by hand. Then start the engine and allow it to run with the A/C on For 5 minutes at idle RPM.

Raise the engine RPM to 1,500 and check the sight glass for bubbles.

NOTE: Cycling clutch systems will produce bubbles in the sight glass normally when the clutch engages. Therefore, check the sight glass for bubbles only after the clutch has been engaged for 5 seconds or more. If bubbles continue, then add refrigerant vapor into the low side as follows until the sight glass is clear.

6B. If necessary, charge more refrigerant into the low side. For this operation, the refrigerant must be in vapor (valve up), not liquid form. Run the engine at 1,500 RPM with the A/C on and set to maximum cool. the blower speed should be on the highest setting.

Slowly open the low side manifold valve. Keep the low side pressure below 40 psi by using the low side manifold valve to regulate the flow of refrigerant into the system.

7. When the system is fully charged, close the low side manifold valve. Close the valve at the refrigerant source.

8. Do an A/C performance test according to the chart on page 18.


Leak Detection Testing

1. Use your electronic leak detector to check the entire system for refrigerant leaks.

Final Matters

1. Disconnect the manifold gauge set. Install the service port caps.

REFRIGERANT CAPACITIES

Model Capacity

Stanza Wagon 2.0-2.4 lbs
Van 2.9-3.3 lbs: (without cool box)
3.1-3.5 lbs. (with cool box)
Maxima 2.0-2.4 lbs.
300ZX 2.0-2.4 lbs.
200SX 2.0-2.4 lbs.