What refrigerant can top off R22?

Author: Eriberto Harris  |  Last update: Friday, February 6, 2026

Freon™ MO99 can be used to retrofit R-22 heat pumps . Based on system testing, similar efficiency and slightly lower capacity can be expected.

What refrigerant can I use to top off R-22?

Freon MO99 is the closest capacity match to R-22 compared with most other no-oil change refrigerants.

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.

Which Freon is compatible with R-22?

Freon™ MO29 refrigerant: Extends system life using the same equipment as R-22, so a system with an R-22 leak does not need to be completely replaced or upgraded.

Can you flush R-22 to R-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 Topping off R22 Systems with other Refrigerants OK (REALLY)??

What happens if you put R-410A in a R-22 system?

The pressure can become high enough for parts of the system to rupture. At the very least, leaks will occur.

Can you top off R-22 with R407C?

Mixing R22 with R407C

According to the 609 EPA rule, mixing refrigerants is illegal and anybody caught doing so will be heavily fined. Although you may this restriction is primarily political we would like to give you a basic education to explain the two most devastating effects of such action: To the environment.

What is the best substitute for R-22?

Freon™ MO99 refrigerant is a relatively affordable and eco-friendly alternative for R22 air conditioners. You can use it to revive older systems with little to no refrigerant charge, as well as systems that need replacement components.

Can you put 407C in a R-22 unit?

Using these retrofit guidelines, many R-22 systems can be retrofitted for use with Freon™ 407C in air conditioning, heat pump applications, and refrigeration applications to allow existing equipment to continue to operate safely and efficiently, even after R-22 is no longer 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.

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.

Can you drop MO99 on top of R-22?

Can R-22 be topped off with Freon™ MO99? No. Freon™ MO99 should not be used to top off R-22 systems. Mixing refrigerants is not recommended.

Can I put R134a in a R-22 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.

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.

Can R-22 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.

Can you top off R-22 with 422B?

Mixing refrigerants is not recommended. R-22 replacements should not be used to top off R-22 systems. R-22 should be recovered using appropriate equipment and managed according to U.S. EPA guidelines specified in Section 608 of the U.S. Clean Air Act.

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

EPA regulations prohibit mixing different types of refrigerants.

What is compatible with R-22 refrigerant?

  • Also Acceptable: R427A, R404A, R407C.
  • Also Acceptable: R422D, R427A.
  • * Note: If compressor is being replaced as part of the service call on a small system, install a POE compressor and retrofit to the better capacity/lower GWP blend.

Can I put 410A in a R-22 system?

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.

Can you put 407C in a R-22 system?

R-407C should be used only in systems that currently use R-22. It should not be mixed with R-22 or any other refrigerant. 5. The capacity of the existing R-22 thermal expansion valve (TEV) will be approximately the same when using R-407C.

What gas can replace R-22 refrigerant?

R417A refrigerant is an HFC mixture that serves as a substitute for R22. It is compatible with traditional lubricants. In most cases, the lubricant type does not need to be changed in the event of retrofitting.

What is the retrofit refrigerant for R-22?

Among those products is Freon™ MO99™ (R-438A), a retrofit refrigerant for R-22 that does not require an oil change. Freon™ MO99™ works with: Residential and commercial air conditioning systems (rooftop and indoor packages units, direct expansion chillers, split systems)

What can I use instead of R-22 refrigerant?

R410A is the most common, but others include R134a, R407C and R407A. These refrigerants cool interior spaces just as effectively as R22 with no ozone depleting characteristics and relatively low Global Warming Potential (GWP).

Is R-407C banned?

R407C will, however, be phased out in 2025 in systems with less than 3kg charge. R410A air conditioning systems with charges greater than 3kg – including most VRF applications – are not affected. Systems with less than 3kg charge will be banned from 2025, with equipment using R32 an alternative option.

Does 407C run higher pressure than R-22?

Heating mode The compressor pressure ratio of R-407C was 0.7% to 9.3% higher than R-22 for the two heating mode test conditions.

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