Service Procedure

SERVICE PROCEDURE

1. PRELIMINARY CHECKS

a) Inspect the existing components for proper operation.

^ The system must be leak-free, since the R-134a molecules are smaller than R-12.
^ The original (R-12 type) compressor must be operating properly for continued use.

b) Retrofit alone will not correct a system failure. The R-134a A/C system retrofit is intended as an alternative, only if the original refrigerant type is unavailable. Retrofit should be proformed after thorough diagnosis and repair is completed.

2. REFRIGERANT RECOVERY

IMPORTANT:
The existing R-12 refrigerant should be recovered using the appropriate R-12 recovery equipment. R-12 refrigerant should never be vented to the atmosphere or introduced into equipment not intended for R-12 refrigerant.

NOTE:
The recovery procedure prior to R-134a retrofit is different that normal (non-retrofit) recovery procedure. The R-12 refrigerant will be recovered through the high-side service port only. Recovery through the low side will not effectively remove the R-12 from the receiver/drier, resulting in possible damage to the retrofitted system.

a) Connect the recovery hose from the R-12 recovery cart (ACR3) to the middle port of A/C gauge set.

b) Open the oil drain valve on the ACR3 cart and drain the oil completely. Failure to do so could cause excessive amounts of oil to build up the separator, resulting in damage to the recovery cart compressor.

c) Start the engine with the hood up, and open the windows.

d) Set the A/C & ventilation controls to the following:
^ A/C Switch - "OFF"
^ Temperature - coldest setting
^ Fan Speed - maximum speed
^ Air-Source - outside/fresh air
^ Air Selector - any setting

e) With the vehicle compressor OFF, turn the cart on and start the recovery cycle.
^ Open both the high and low side on the gauge set.
^ After the recovery carts shuts off the first time, wait 5 minutes. If the pressure on either the high or the low side rises above 0 PSI, restart the recovery process.
^ After the second shutoff, wait 2 minutes. If the pressure again rises above 0 PSI, restart, and after shutoff, again wait 2 minutes.
^ The process can be stopped when the pressure does not rise above 0 PSI after 2 minutes.

f) Shut the engine off when the recovery process is complete.
^ Remove the R-12 reclaim hose.
^ Remove the A/C gauge set.

g) Once the refrigerant has been properly removed, the system is now ready for retrofit.
^ Any necessary repairs should be done at this time.

3. RECEIVER DRIER INSTALLATION

If the existing receiver contains a pressure switch, it should be transferred to the new receiver drier and installed with a new O-ring. New O-rings should also be used at the receiver drier connections.

4. HOSE / PIPE / ADAPTER INSTALLATION

Depending on application, either R-134a service valve adapters or hoses equipped with the R-134 service ports are required in both the high and the low-pressure side. Refer to R-12 to R-134a A/C Conversion/Retrofit Parts Application Chart in the PARTS INFORMATION section for specific application requirements.

IMPORTANT:
If adapters are to be installed, the existing service valve core must be removed to eliminate an unnecessary restriction. Always use new O-rings when replacing pipes or hoses.

5. CAUTION LABEL





A new caution label (P/N 8-21030-857-0) must be installed near the existing R-12 caution label. Begin by marking the label (using a typewriter or ballpoint pen) with the name of the person or facility that performed the retrofit, the type and quantity of refrigerant, and type of oil. Select a location as close to the original yellow R-12 caution label as possible and clean the selected area. Apply the label and then apply the clear overlay over the new label. (Figure 1)

NOTE:
Do not remove, cover or render unreadable on the existing R-12 caution label. However, cross out the R-12 refrigerant charge amount on the existing label with a permanent (preferably black) marker.





RETROFIT LABEL INFORMATION

6. OIL CHARGING





Three types of PAG oils are used with Isuzu air conditioning systems depending on compressor type (swash, radial, or rotary type). Be sure to use the correct oil. Once the system has been sealed, connect an R-134a gauge manifold to the high-pressure service valve of the system and an R-134a vacuum pump. Connect one end of the low pressure charging hose to the low-pressure service valve of the system and place the other end into the PAG oil container. With the vacuum pump in operation, the pump will draw the oil from the container into the system after it has evacuated all of the air. Some R-134a charging equipment may have oil-charging capabilities and can be used as an alternative to this procedure.

7. EVACUATION AND REFRIGERANT CHARGING





Once the oil has been charged into the system, the evacuation process can be started. Connect the end of the hose that was in the oil container to the gauge manifold and evacuate for a minimum of 30 minutes. The new R-134a refrigerant should be charged using the appropriate R-134a charging equipment according to the following chart. It is not recommended to vent R-134a refrigerant to the atmosphere~and it should never be introduced into equipment not intended for R-134a refrigerant.

NOTE:
30lbs canister of R-134a refrigerant are available through AIPDN (PART # 2-90531-813-0).