DIY Network

A/C Retrofit -- R-134A Refrigerant Upgrade From "Weekend Mechanic" episode WKM-110

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Figure A Figure B Figure C Figure D Figure E Figure F Figure G Figure H Figure I Figure J

Refrigerant Upgrade

With the compressor and other faulty components replaced, the final procedure in the a/c upgrade is to charge the new system using the R-134A retrofit kit.

• To add the new refrigerant, R-134A charge-port adapters must be installed onto the old R-12 system. R-134A refrigerant gas has a different density from the original R-12 gas. The new port adapters compensate for this.
  
  
  
• There are two separate adapters (figure A) for the two charge ports. The larger of the two goes on the high-side port, the smaller goes on the lower. The low-side draws refrigerant from the evaporator. The high-side pushes it through the a/c system.
  
  
  
• The low-side adapter has a Schrader valve incorporated into it. A Schrader valve allows air or gas to enter -- but not escape from -- a pressurize system, similar to the way an inflation valve works on a tire.
  
  
  
• The old Schrader valve must be removed from the accumulator before the adapter can be installed. Remove the old valve by using a valve-core remover (figure B ). Once the old Schrader valve is removed (figure C), discard it.
  
  
  
• Install the low-side adapter onto the accumulator charge-port (figure D). The adapters have lock-tight already applied to the threads, so once they are installed, they are fixed permanently.
  
  
  
• Since the high-side adapter doesn't have a built-in Shcrader valve, install a new Schrader valve in the high-side charge-port first. Before installing the high-side adapter the high-side adapter, however, some leak-detection dye is introduced into the system through the port opening (figure E). If a leak should ever develop later on, the dye will help pinpoint the leak by use of an ultra-violet light.
  
  
  
• Once the dye has been added, install the adapter.
  
  
  
• With the adapters installed, the system must be evacuated with a vacuum for about 60 minutes to remove any moisture from the system.
  
  
  
• Hook up the vacuum device (available for rent from auto-parts suppliers), according to the directions that come with the kit (figure F). Follow the directions and apply the appropriate amount of vacuum pressure, as indicated on the kit's dial-set.
  
  
  
• Once the system has been completely evacuated, the new refrigerant can be added according to the directions that come with the retrofit kit. In a retrofit, the amount of R-134A refrigerant needed may be less than the amount of R-12 that was used previously. Consult your service manual and instructions to determine the proper amount. In our case, the new capacity is 30 ounces of refrigerant.
  
  
  
• One by one, connect the refrigerant canisters to the threaded connector (figure G), tap the can and charge the system. Once the can is tapped, add the refrigerant with the vehicle's motor running.
  
  
  
• As the system is charging, turn on the a/c switch, and turn the control to "max," or the highest (coldest) setting. Check the temperature of the output at the vent using a thermometer (figure H).
  
  
  
• The dial gauges will give indication of when the appropriate amount of refrigerant has been added (figure I). Once the proper setting is reached, the high-side connection is removed, thus purging the remaining refrigerant from the hoses and adding it to the system. Then the other connection can be removed to complete the charging process.

  Note: The charging procedures are outlined in detail in the retrofit kit.
  
  
  

• The retrofit kit will come with a label, which should be displayed on the compressor where it can be seen easily. This will prevent the wrong refrigerant from being added accidentally during later servicing.
  
  
  
• Once the retrofit charging is complete, an ultraviolet light can be used to check for leaks. Any leak-detection dye that escapes (indicating a refrigerant leak) will show up brightly under u/v light. (In our demonstration, a drop of dye was place on the fitting (figure J) to show what a real leak would look like.)

RESOURCES :

The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books

How Cars Work
Author: Tom Newton
ISBN: 0966862309
Publisher: Black Apple Press

Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896