Recharging Your Air Conditioning Robinair 34788 Instructions

rob-34788lg   Recharging Your A/C System

   Set up and operation part 1 Robinair 34788


Set up and operation part 2 Robinair 34788


                                                            Set up and operation part 3 Robinair 34788


With all of the regulations on refrigerant, it is a good idea to recharge your air conditioning system the correct way.  The refrigerants used in a/c systems are known to cause ozone layer depletion, so as a technician or an individual dealing with these refrigerants we must not release any of these chemicals into the air. This means properly removing and recharging your a/c system.

When you are dealing with your system or a customers a/c system you first must identify the type of system.  There are two major types of a/c systems out there today, they are; R12, and R134a systems.  You can most of the time tell whether or not you have R12 or R134a by simply looking at the connectors.  Most recharging stations today only have the R134a connectors on them.  The other thing is if you do come across an R12 vehicle you will have to do what is called a retrofit and convert it to R134a.  The retrofit is because R12 is more harmful to the environment so the auto industry switched to R134a.

In this article, we will assume that you have all of the proper legal certifications, the proper training, and an R134a system.  If you do not have an R134a system you will want to look at getting a retrofit kit such as this Basic Retrofit Kit w/PAG Oil.

Before we get started, I will be discussing some of the tools you will need.  I will be using the Robinair 34788 R-134A Refrigerant Recycler Cool Tech for the recovery system.  Along with recovery equipment, you are going to need to locate the proper oil for the vehicle that you are doing the recovery on.

The Procedure

  1. First you are going to locate these specifications for the exact vehicle you will be performing the task on.  You will need to know the oil type, weight of the oil, the amount of refrigerant in the system, and what type of system it is (TXV or Orifice Tube).
  2. Next start the vehicle and let it run until it is at proper operating temperature.
  3. Now that you have located all of the information that you need and properly warmed the vehicle up, you will need to locate the high side and low side ports.  The high side will have a red cap on it, and the low side will have usually a black or blue cap.  You may want to consult the service manual for the location of these to save time.
  4. Next you will want to connect the red hose from your A/C Recovery System to the high side port, and then you will want to connect the blue hose to the low side port.
  5. Once you have the hoses connected, open the caps all the way by turning the valves open.
  6. Now that your hoses are connected the sides should both have pressure on the gauges.  I am assuming that you already discovered that the system needed to be recharged, so I will not go into great detail on the differences in the gauges throughout the procedure.
  7. Before starting the machine, you will want to take a note on how much oil is in the tank on the side, because after you are done you will then compare the levels to see how much oil you need to add.
  8. You will also want to identify and make sure that there are no sealants in the a/c system, these can damage recovery equipment and the system needs to be equipped with a filter if dealing with sealants.
  9. Now you are going to want to turn the AC Recovery System on.  It will basically walk you through the steps. You will want to push the recover button on the machine.
  10. The machine will begin recovering the refrigerant.  You will notice that the pressure is dropping.  You may want to take a heat gun to the receiver dryer/accumulator to help in recovering all of the refrigerant.
  11. Once the AC Reclaimer is done it will automatically shut off.  At this point you will want to look at the pressure.  It should be a vacuum which means it is below zero.  If you have removed all of the refrigerant then it should stay below zero for five minutes.  If it goes above zero then restart the recovery.
  12. Once you have finished recovering all of the refrigerant you will want to write down the amount that the AC Recovery recovered.  You will also want to check the oil level and determine how much oil was recovered also.
  13. Now before recharging the system you will need to add the proper oil and the amount needed to make up for the amount recovered.  You will always want to add one more ounce than you need to the fill container.  This is because when filling the system with oil, a hose sucking air will lead to air in the system and the system will need to be recovered again.  Add the oil you need plus one ounce.  Press the inject oil button and hold watching the container until you have added the amount that you have removed.  Once you have added the oil that you recovered you can pour the extra ounce back into the bottle where it came from.
  14. Finally you will want to set your A/C recover  machine to the amount of charge that your vehicle needs.  Once you have done this let the system charge the vehicle.  Be careful you do not want to bump the machine.
  15. Once the AC Robinair Reclaimer is done it will tell you what to do with the hoses, and how to properly remove them.  You will need to follow the machines instructions and remove both the high side and low side hoses.

Now that you have recharged your a/c system you are going to want to do a performance test on it to make sure that it is working properly and in good performance.  You will want to look up in the service manual for the exact procedure.  Here is a basic procedure that may be applied to most vehicles.

The Procedure

  1. You will need to acquire an A/C gauge set to read the pressures.  Once you have properly connected the gauge set to the vehicle and opened the valves you will want to read pressures.
  2. Now you are going to want to start the vehicle and turn it to MAX AC and RECIRCULATE with the blower on the highest setting.
  3. Now allow the vehicle to run for five to ten minutes to allow it to heat up to operating temperature.  Once the vehicle has you will want to take note of the high and low side pressures on the gauges.  Check this to match the specifications within the service manual.
  4. Now you will need to acquire a thermometer such as this ATD Digital Thermometer.  You will need to take your thermometer and place it in front of the condenser.  You will record the temperature of the air coming into the condenser.  Then with the car still running on all of the settings above take the thermometer and stick in the center dash with the air coming out of the ducts.  Record the temperature.  There should be at least a temperature difference of 30 degrees F.
  5. Next take your thermometer and measure the temperature of the condenser outlet and inlet tubes.  You want to measure the temperatures as close to the condenser as you can.  Record both of these temperatures.  You will then want to subtract the inlet temperature from the outlet temperature and you should get a difference of between 20 and 50 degrees F.  If you have less than the 20 degree difference then this could be due to a poor condenser air flow or a possible overcharge.  If you have a difference over 50 degrees then you may have a possible restriction inside the condenser or a possible undercharge.
  6. Finally if you can get to the inlet and outlet tubes of the evaporator then measure the temperatures as close as possible to the evaporator.  Once you do record the temperatures for the inlet and outlet.  If everything is perfect you don’t want any difference in the temperatures.  If you have a 5 degree F or greater temperature difference on the outlet than on the inlet you may have a possible under charge.  If you have an outlet temperature that is 5 degrees F or greater than the inlet temperature then you may have a possible overcharge.

I hope that these helpful performance tips help you to diagnose some common problems that can occur inside your a/c system.  I encourage you to follow these steps when recharging an a/c system; it will help save the environment for future generations.

Written by: Cody Mammenga an NDSCS Student





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