A/C Refrigerant Recovery/Evacuation/Charging (134a): Procedure

WARNING: 

• Compressed air mixed with the R-134a forms a combustible vapor.
• The vapor can burn or explode causing serious injury.
• Never use compressed air to pressure test R-134a service equipment or vehicle air conditioning systems.

WARNING: 

• Air conditioning refrigerant or lubricant vapor can irritate your eyes, nose, or throat.
• Be careful when connecting service equipment.
• Do not breathe refrigerant or vapor.

NOTE: 

• If accidental system discharge occurs, ventilate the work area before resuming service.
• Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers.
• Do not allow moisture to contaminate the A/C system oil. Moisture in the oil is difficult to remove, and it can damage the A/C compressor.
• Using a thermistor (compact electronic) vacuum gauge may decrease the required evacuation time because you can measure actual moisture level with this tool.
• Air conditioning refrigerant is poisonous. If ingested, get medical attention immediately.

A more efficient way to measure moisture removal is with a special tool called a thermistor (compact electronic) vacuum gauge, measuring vacuum levels in microns. The robinair 48920T (ROB48920T) A/C recover/recycle/recharge machine has a built-in thermistor (compact electronic) vacuum gauge. If you are using a different A/C recover/recycle/recharge machine, a separate gauge, such as the ROB14777 may be used.

Connect the tool according to the manufacturers instructions and allow the vacuum pump to run until the gauge reads 750 microns.

Shut off and isolate the vacuum pump, then observe the gauge reading:

• If the vacuum level remains stable at 750 microns for at least three minutes, all moisture in the system has been removed.
• A slow increase in the micron reading means there is still moisture boiling out of the system. Restart the vacuum pump and continue evacuating.
• A quick increase of micron levels indicates a leak is present in the system or your service equipment. Determine the cause and correct the leak before continuing.

When an A/C System has been opened to the atmosphere, such as during installation or repair, it must be evacuated using an A/C recover/recycle/recharge machine. If the system has been open for several days, replace the receiver/dryer or the desiccant, drain the refrigerant oil , and add fresh oil. Then evacuate the system for several hours before charging it.

1. A/C Recover/Recycle/Recharge Machine - Connect

   1. Connect an A/C recover/recycle/recharge machine to the high-pressure service port (A) and the low-pressure service port (B), as shown, following the equipment manufacturer's instructions.

   Courtesy of HONDA, U.S.A., INC.

2. A/C Refrigerant - Recover

   1. Recover the refrigerant from the A/C system.

   2. Measure the amount of refrigerant oil 

   removed from the A/C system after the recovery process is completed. Be sure to put the same amount of new refrigerant oil  back into the A/C system before charging.

3. A/C System - Evacuate

   1. Evacuate the system. The vacuum pump should run for a minimum of 30 minutes or until the moisture vacuum test passes, to eliminate all moisture from the system. When the suction gauge reads -93.3 kPa (-700 mmHg, -27.55 inHg) for at least 30 minutes, or the moisture vacuum test passes, close all valves, and turn off the vacuum pump.

   2. If the suction gauge does not reach approximately -93.3 kPa (-700 mmHg, -27.55 inHg) in 15 minutes or the moisture vacuum test fails, there is probably a leak in the system. Partially charge the system, and check for leaks.

4. A/C Refrigerant - Leak Check 
5. A/C Refrigerant - Charge

   1. Charge the system with the specified amount of R-134a refrigerant. Do not overcharge the system; the A/C compressor will be damaged. Select the appropriate units of measure for your refrigerant A/C recover/recycle/recharge machine.

   1.5 L engine 

   Refrigerant Capacity:

   435 to 485 g

   15.34 to 17.11 oz

   0.435 to 0.485 kg

   0.959 to 1.069 lbs

   2.4 L engine 

   Refrigerant Capacity:

   415 to 465 g

   14.64 to 16.40 oz

   0.415 to 0.465 kg

   0.915 to 1.025 lbs

6. A/C Refrigerant - Leak Check 
7. A/C System - Test