Can you top off R22 with R134a?

Author: Makenna Larkin  |  Last update: Thursday, January 8, 2026

Mixing refrigerants is always a no-no.

What happens if you put R134a in a R22 system?

No, the compressor will fail. These two refrigerants have very different properties. One of R22 and R134a is high pressure and the other is low pressure. They don't mix chemically and don't have the same boiling point, leading to inefficiencies and eventual compressor failure.

What refrigerant can I use to top off R22?

Freon™ MO99 can be used to retrofit R-22 heat pumps .

Which freon can be mixed with R22?

You should not mix R-22 with any other refrigerant. However, some systems can support EITHER R-22 refrigerant OR R-410A refrigerant. It depends on the system, and you may need to look at your system's specification sheet to see if your system is compatible with another refrigerant.

Can R22 be topped up?

Having said that, some unscrupulous contractors will top up R22 with a similar refrigerant like R438a in an attempt to save themselves time and money. You simply cannot use an alternative refrigerant to top up a system charged with R22 and no amount of “she'll be right, mate” will ever change that.

Is Topping off R22 Systems with other Refrigerants OK (REALLY)??

Can you recharge an R-22 system?

If you have an older air conditioning system that is low on refrigerant, recharging it is not a simple process. Because there is no more production of R22 and it is illegal to import, you will need to speak with a professional about how to refill an R22 air conditioner.

Is there a substitute for R-22 refrigerant?

Freon MO99 is the gold standard for R-22 alternatives and was developed by the same scientists who engineered Freon R-22. The benefits of Freon MO99 include: Capacity — The ability of Freon MO99 to heat or cool a given space is closer to Freon R-22 than any other refrigerant on the market.

What is a drop-in substitute for R-22?

R-421A is a drop-in replacement for R22 systems. With this refrigerant there is no need to change the oil. Simply recover the R22 and recharge with R421A. Experiencing R421a problems? Read this guide.

What happens if you mix R-22 with another refrigerant?

At the very least, leaks will occur. Mixing refrigerants is not an option either. This will contaminate the system, and the R22 will not evaporate under the higher suction pressure that R410A requires.

What is the difference between R-22 and 134a freon?

R134a and R22

The capacity of R134a is smaller than that of R22, and the pressure is lower than that of R22. Due to these features, an R134a air conditioner with the same capacity must be equipped with a larger compressor with a larger evaporator, condenser, and piping.

Is it illegal to refill R-22 refrigerant?

As of January 1, 2020, production and import of R22 refrigerant will be illegal in the United States. Of course, continued use of your air conditioner (AC) or heat pump system using R22 refrigerant is allowed.

Can you put 427A on top of R-22?

Can I mix Forane® 427A and R-22? Mixing refrigerants is not recommended as it creates a new refrigerant that is not EPA approved. In addition, it contaminates the R-22. Proper calculation of superheat and subcooling becomes extremely difficult, which could result in damaging the compressor.

How much is R-22 Freon per pound?

R-22 refrigerant prices range from $90 to $250 per pound. Since you'll need between 6 and 12 pounds to refill a home AC, costs can reach between $660 and $2,400 for a refill of R-22 refrigerant.

What refrigerant is compatible with R134a?

There are three refrigerants that can be used to replace R-134a: R-1234yf, R-152a, and R-744. More on these replacements later.

Can you put 410a Freon in a R22 system?

As you might imagine, this isn't going to go well for your air conditioner or heat pump. Long story short? Never mix R-22 and R-410a. Unless of course you are looking to destroy your HVAC system, then, by all means, go live that dream.

What year did they stop using R134a refrigerant?

In the United States, vehicles produced after 2021 no longer contain R-134A in the air conditioning system. In other parts of the world, including the United States, there are restrictions around using 1,1,1,2-tetrafluoroethane. Specifically, in California, retailers can deny selling customers canned R-134a.

What can you convert R-22 to?

Indeed, you can take that old supply of R-22 and make it into R-410A. The alterations will affect the air conditioning unit. Although they're both refrigerants, the higher efficiency of R-410A requires an upgrade to the equipment.

Can you reuse recovered R-22?

In truth, recycled R-22 removes some of the contaminants through separation and filtration, and recycled R-22 can only be used in the same system it was taken from.

Do you have to flush R-22 lines for 410A?

When you replace an air conditioner or heat pump and upgrade from R-22 to R-410A, the ideal solution is to replace your refrigerant lines. This is because the mineral oil used in R-22 systems is not compatible with the new R-410A refrigerant and oil.

Is there a refrigerant that can be mixed with R-22?

So… what refrigerant can be mixed with R-22? None. You can't mix refrigerants.

What refrigerant can replace R-22?

An R-22 Refrigerant Replacement for Direct Expansion Refrigeration. Freon™ MO29 (R-422D) refrigerant is a low-toxicity, non-ozone depleting hydrofluorocarbon (HFC) replacement for R-22.

Why was R-22 phased out?

Because R-22 depletes the ozone layer, production and import was further limited in 2010. In 2020, R-22 will no longer be produced or imported. After 2020, only recovered, recycled, or reclaimed supplies of R-22 will be available.

How much does it cost to convert R-22 to R-410A?

How much will an R-22 to R-410A conversion cost? The actual cost will depend on many things, including where you live, but most of the time R-22 conversions start at around $2,000 and go up from there. The higher end of that range is somewhere around $4,500 to $4,600.

Can you mix MO99 with R-22?

Mixing refrigerants is not recommended.

Will AutoZone recharge my AC?

An AC leak will lead to warmer air from your vents over time. In most cases this can be fixed with a proven stop leak additive to seal up any leaks. When it's time for an AC recharge, turn to AutoZone.

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