Rick's Free Auto Repair Advice

R-134a into R-1234yf system

Can you retrofit R-134a into R-1234yf system?

No, not legally

Legality aside, can you do it?

There are many reasons why this won’t work

1) The R-1234yf expansion valve is incompatible with R-134a

The expansion valve for R-1234yf refrigerant will not work with R-134a refrigerant. Retrofitting R-134a into an R-1234yf expansion valve will result in improper refrigerant flow causing a loss of cooling performance or durability concerns.

2) The R-1234yf suction line heat exchanger will cause compressor problems

Most compressors used in R-1234yf systems use a control valve for pressure control of the variable displacement features. The suction line heat exchanger will affect the suction line pressure drop if used with R-134a refrigerant, which will then negatively affect the pressure control in the compressor. The result will be a drop in cooling and evaporator coil freeze-up.

3) Dual zone control systems can be damaged by using R-134a in an R-1234yf system

In dual zone control vehicles that use two evaporators, using R-134a can cause oil trapping in the rear evaporator, resulting in compressor failure.

4) R-134a in an R-1234yf system will affect evaporator operation

Evaporator control can be either pressure or temperature regulated. Different sensors are required if you plan to change to R-134a. In some vehicles replacing the evaporator temp sensor means removing the entire dash and heater box.

R-1234yf systems that control freeze protection by pressure sensors may experience cooling loss if charged with R-134a.

5) Mixing R-134a and R-1234yf will cause problems

Mixing the two refrigerants will cause evaporator freeze up issues.

6) Mixing R-134a and R-1234yf will result in full contamination

If you ever need to have a shop work on your AC system, the mixture can contaminate the shop’s recovery machine, resulting an a significant upcharge to you.

©, 2022 Rick Muscoplat

Posted on by Rick Muscoplat



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