How to complete an A/C Conversion R-12 to R134a?

ADAM62P

MEMBER
1988 TOYOTA COROLLA
AUTOMATIC
216,000 MILES

Hello! I drive the car listed above SR5. The car's air conditioning system is not functioning correctly; it only blows hot air, and I think the problem may be related to the refrigerant. I initially brought the car to a local auto repair shop, where I spent around $200 for them to fix it. Unfortunately, the problem was not resolved. After researching online and downloading documents from AllData, reading service manuals, as well as watching a YouTube video, I am still feeling quite confused and uncertain about how to convert my car from r-12 to r134a myself. I am in need of guidance on how to successfully convert/retrofit my car's A/C system from R-12 to R134a. I would greatly appreciate it if you could provide me with clear instructions, step-by-step guidance, or any resources that can help me, but most importantly what I need to buy.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

As far as retrofitting from R12 to R134a is concerned, the most important thing to remember is that the system needs to be flushed of the old Freon and old oil. The R12 system used a mineral oil to lubricate the system. R134a requires PAG oil.

1. Gather the Necessary Materials:

R134a refrigerant
Retrofit kit (includes adapters, O-rings, and retrofit label)
Vacuum pump
AC manifold gauge set
AC oil suitable for R134a systems
Safety goggles and gloves
Service manual for your vehicle (for specifications)

2. Discharge the Old R12 Refrigerant:

Properly recover and dispose of the old R12 refrigerant. It's illegal to release it into the atmosphere.
3. Replace the Receiver-Dryer and Expansion Valve:

The R12 components, like the receiver-dryer and expansion valve, may not be compatible with R134a. Replace them with components designed for R134a systems.

4. Inspect and Replace O-rings:

Carefully inspect all AC system O-rings and replace them with the ones provided in the retrofit kit.

5. Flush the AC System:

Use an AC flush kit to clean out any remaining R12 oil and debris from the AC lines.
6. Add PAG Oil:

R134a systems use Polyalkylene Glycol (PAG) oil, while R12 systems use mineral oil. Add the appropriate amount of PAG oil for your vehicle's AC system specifications.
7. Evacuate the System:

Connect a vacuum pump to the AC system and evacuate it for at least 30 minutes to remove any air and moisture.
8. Charge the System with R134a:

Connect the AC manifold gauge set and slowly charge the system with R134a refrigerant according to your vehicle's specifications. Be sure not to overcharge.

9. Check for Leaks:

Use an AC leak detection kit to check for any leaks in the system.

10. Monitor Performance:

Run the AC system and monitor its performance. Ensure that it's cooling properly and maintaining the correct pressure levels.

11. Retrofit Label:

Place the retrofit label on a visible spot under the hood to indicate that the system has been converted to R134a.

Let me know if this helps or if you have questions.

Joe