If a contractor quote or search result mentions R438A, MO99, R422B, NU-22B, or R407C as an R22 replacement, do not treat those names as interchangeable shopping labels. They are different retrofit paths for older R22 equipment, and the right buying decision depends on the system, lubricant, service scope, recovery plan, and documentation behind the recommendation.
For a system that will remain on R22, start with the active 30 lb R22 refrigerant product page. If the service plan specifically supports R407C, use the current 25 lb R407C refrigerant product page for package details. The comparison below is meant to help purchasing teams ask better questions before either product page becomes a purchase order.
The Short Answer
R438A, commonly sold as MO99, is marketed as an R22 retrofit refrigerant that usually does not require an oil change. Chemours says Freon MO99 (R438A) is compatible with mineral oil, POE oil, and alkylbenzene oil, and is used in residential and commercial air conditioning as well as low- and medium-temperature refrigeration applications.
R407C is a different HFC blend. Arkema describes Forane 407C as formulated to closely match R22 properties in air-conditioning applications, but also states that R407C is completely immiscible with mineral oil and requires a complete change to POE oil when retrofitting an R22 installation. That oil difference is one of the main buyer-facing distinctions.
R422B, often associated with NU-22B language, is another retrofit blend used around R22 air-conditioning applications. National Refrigerants describes R422B as designed to match R22 in air conditioning, with a slight capacity reduction and a hydrocarbon component intended to help oil return in systems with mineral oil or alkylbenzene. It also warns that complicated piping or large hold-up volumes may require POE.
Comparison Table for Purchase Files
| Buyer question | R438A / MO99 | R422B / NU-22B | R407C |
|---|---|---|---|
| Common reason it appears in searches | R22 retrofit option promoted as a no-oil-change path in many systems. | R22 air-conditioning retrofit option, often discussed with oil-return language. | Widely discussed R22 retrofit candidate for air-conditioning applications. |
| Oil issue to verify | Ask whether the contractor is relying on existing mineral oil, AB, or POE and whether the system layout supports that plan. | Ask whether oil return is adequate or whether POE must be added because of piping or volume. | Expect a POE oil plan to be documented for an R22 retrofit. |
| What the buyer should not assume | That "no oil change" means no retrofit work, no leak repair, or no system labeling. | That hydrocarbon-assisted oil return solves every system layout. | That R407C can be topped off into R22 or used without a written retrofit scope. |
| Best next document | Manufacturer retrofit guideline plus contractor proposal for the exact unit. | Manufacturer product information plus oil-return notes for the actual piping layout. | Equipment approval, lubricant plan, service scope, and charging/labeling record. |
Why "R22 Replacement" Is Not Enough
A phrase such as "R22 replacement refrigerant" only tells you the search category. It does not tell you whether the system has been diagnosed, whether the existing charge was recovered, whether the leak was repaired, whether the lubricant plan is acceptable, or whether the equipment manufacturer will support the conversion.
EPA's alternative-refrigerant guidance makes the same point from a regulatory and risk perspective: SNAP acceptability does not decide whether an alternative will perform properly or be compatible with a specific air-conditioning or refrigeration system. EPA also says the best performance and compatibility information comes from the system and component manufacturers, not from a generic substitute claim.
That is why the purchase file should separate three decisions: whether to keep servicing with R22, whether to retrofit to a documented alternative, or whether to replace the equipment. The broader R22 replacement options framework can help with that first-level decision before a buyer compares cylinder listings.
Questions to Ask Before Ordering
Use these questions when a quote names R438A, MO99, R422B, NU-22B, or R407C:
- What refrigerant is in the system now? Confirm the nameplate, prior service tags, and any retrofit label.
- Has the leak or failure been diagnosed? A retrofit refrigerant should not be a shortcut around leak repair or compressor evaluation.
- Will the existing R22 be recovered? A conversion is not the same as topping off one refrigerant with another.
- What lubricant is in the compressor? Ask whether the plan depends on mineral oil, alkylbenzene, POE, or an oil change.
- Does the piping layout affect oil return? Long lines, risers, receivers, and unusual compressor locations can change the answer.
- What parts are included? Filter drier, seals, leak repair, evacuation, charging method, labels, and performance checks should be spelled out.
- Who is eligible to buy and handle the refrigerant? Keep purchaser evidence, invoices, SDS access, and the final service record together.
When R407C Is the Better Fit to Discuss
R407C belongs in the conversation when the contractor has a documented R407C retrofit plan and the oil change or POE requirement is already accounted for. It is especially important to keep R407C separate from an existing R22 charge. If the immediate question is mixing or topping off, read Can You Mix R407C with R22? before ordering anything.
The published R22 vs R407C comparison is useful for the R22-to-R407C branch of the decision. This article adds the missing comparison point: some buyers are not just choosing between R22 and R407C. They are also seeing MO99, R438A, R422B, or NU-22B language and need to know which questions change.
When Continuing With R22 May Still Be the Cleaner Order
Not every older system needs to be converted immediately. If the system is serviceable, the technician has identified a repairable leak, and the service plan calls for R22, buying the refrigerant named by the equipment file may be simpler than introducing a retrofit. That decision still needs eligible purchasing, safe receiving, and proper storage.
Pause any order if the quote relies on vague language such as "R22 equivalent," "drop-in," or "same as Freon" without naming the refrigerant and the conversion scope. A cheaper cylinder can become expensive if the system cannot be serviced cleanly later, if the charge is mislabeled, or if the service team cannot recover and reclaim the refrigerant properly.
Compliance and Record Checks
EPA's refrigerant sales restriction covers ozone-depleting substances and many substitute refrigerants sold in cylinders, cans, or drums. For stationary refrigeration and air-conditioning equipment, EPA generally limits purchases to Section 608-certified technicians or qualifying employers and authorized representatives. Sellers also have invoice and purchaser-record responsibilities.
For buyers, the practical record set is straightforward: diagnosis, selected refrigerant, retrofit guideline or manufacturer support, oil plan, recovery plan, invoice, SDS access, delivery record, and final system label. The record should make clear why the ordered cylinder matches the service plan.
FAQ
Is R438A the same as MO99?
MO99 is a trade name commonly associated with R438A. Use the cylinder label and manufacturer documentation rather than relying on a nickname alone.
Is R438A or MO99 a drop-in replacement for R22?
Do not use "drop-in" as a purchasing approval. Even when a product is marketed as a no-oil-change retrofit, the system still needs recovery, leak repair, component checks, charging guidance, and labeling.
How is R407C different from MO99?
The major buyer-facing difference is the oil plan. MO99 is marketed as compatible with traditional and new lubricants, while Arkema states R407C requires a complete change to POE oil when retrofitting an R22 installation.
Where does R422B fit?
R422B is another R22 retrofit blend. National Refrigerants describes it as an air-conditioning retrofit product with hydrocarbon-assisted oil return, but notes that complicated piping or large hold-up volumes may still require POE.
Should I buy R22, R407C, or another retrofit refrigerant?
Buy the refrigerant named in the documented service plan. If the system remains an R22 system, R22 may be the cleaner order. If the system is being retrofitted, the contractor should identify the exact alternative refrigerant and the full conversion scope.
Make the Retrofit Name Earn Its Place in the File
R438A, MO99, R422B, NU-22B, and R407C all appear around R22 replacement searches, but a buyer should not choose from names alone. Ask for the equipment basis, oil-return logic, recovery plan, leak repair scope, labeling step, and purchaser records. When the file points to R22 or R407C, use the live product page for current package details. When the file points to another retrofit product, keep the documentation strong enough that the next technician can understand exactly what changed.
Authoritative references: EPA alternative refrigerant purchase questions, EPA refrigerant sales restriction, Chemours Freon MO99 product information, National Refrigerants R422B product information, and Arkema Forane 407C product information.