Type II: High-pressure

Study guide

License Method EPA 608 prep. This guide was checked against the eCFR (40 CFR Part 82 Subpart F and Part 84 Subparts B and C) as of October 2026. Rules that changed recently are marked NEW or CHANGED.

What Type II covers

A Type II certification lets you maintain, service, repair, or dispose of medium-pressure, high-pressure, and very high-pressure appliances. That excludes small appliances (Type I) and motor vehicle A/C (Section 609). In practice it covers most of the work done by residential and commercial HVAC/R techs: split systems, rooftop units, walk-ins, reach-ins with remote condensers, supermarket racks, and high-pressure chillers. (40 CFR 82.161(a)(1)(ii))

If you work on an MVAC-like appliance, meaning off-road equipment like a tractor or excavator with an open-drive compressor and 20 lb or less of refrigerant, you need either Type II or Section 609 certification. (82.161(a)(1)(v))

On the exam, the Type II section is 25 questions drawn from EPA's test bank, given in a closed-book, proctored setting. You need 70%, which works out to 18 of 25 correct, or 72%. (Appendix D to Subpart F)

Pressure classes: know the definitions

EPA classifies an appliance by the refrigerant's liquid-phase saturation pressure at 104 °F (40 CFR 82.152):

Memory tip: "45, 170, 355 at 104." Low is under 45, medium runs to 170, high runs to 355, and very high is everything above that. R-134a is the one most people get wrong. It's medium-pressure, but it's still Type II.

Required evacuation levels (Table 1, 40 CFR 82.156)

Before you open an appliance or dispose of it, you must recover the refrigerant, including all the liquid, to these levels using certified recovery equipment. You must also verify that the level was reached before you open the system.

Vacuum levels are inches of mercury below standard atmospheric pressure (29.9 in. Hg).

CHANGED (2016 rule): Older study materials list separate rows for "HCFC-22" and "other high-pressure" appliances, so an R-410A system under 200 lb shows 10 in. Hg. The current service-practice table in 82.156 groups all high-pressure appliances together, so any high-pressure appliance under 200 lb now goes to 0 in. Hg (0 psig). The old split only survives in Table 2 of 82.158, which sets the test standard for recovery machines, not field practice.

Memory tips

• The column depends on when the recovery machine was made, not when the appliance was made. The cutoff date is November 15, 1993.
• "Bigger and lower pressure means deeper vacuum." Medium-pressure systems of 200 lb or more need the deepest Type II vacuum, 15 in. Hg.
• Pre-1993 machines only ever need 0 or 4 in. Hg.
• Very high-pressure is always 0.

Watch for the pressure rise

After you reach the target vacuum, wait a few minutes. If the pressure rises, refrigerant is still boiling out of trapped liquid or out of the oil. Keep recovering until the vacuum holds.

Exceptions to Table 1

1. Non-major repair, with no evacuation to the atmosphere afterward. For a medium-, high-, or very high-pressure appliance, you may open it once it's at 0 psig or lower instead of the full Table 1 level. (82.156(a)(1)(i))
2. Oil changes. Evacuate the appliance, or the isolated part, to 5 psig or lower before you open it, or drain the oil into a system receiver that's at 5 psig or lower. Changing oil at a higher pressure is a violation. (82.156(a)(1)(iii))
3. Leaky appliances. If leaks make the Table 1 level impossible to reach, or reaching it would badly contaminate the refrigerant: isolate the leaking components from the non-leaking ones, take the non-leaking parts to Table 1 levels, and take the leaking parts to the lowest level you can reach without contaminating the refrigerant. That level can never be above 0 psig. (82.156(a)(2))

What counts as a "major" repair

A major repair is any job that removes the compressor, condenser, evaporator, or an auxiliary heat-exchange coil, or that uncovers an opening of more than 4 square inches of flow area for more than 15 minutes. (82.152) Swapping a filter-drier or a valve quickly is usually not major. Pulling a compressor always is.

Other recovery rules

• System-dependent (passive) recovery relies on the appliance's own compressor or pressure. You can't use it on appliances holding more than 15 lb, unless it's a pump-out unit that's permanently attached. (82.156(e))
• Recovery equipment made or imported on or after Nov 15, 1993 must be certified by an EPA-approved testing organization and carry a permanent label. The label names the testing organization and the appliance category, and shows the date of manufacture and the serial number. (82.158(a), (h))
• All hoses on recovery equipment need low-loss fittings. (82.158(d)(7))
• Recovery equipment for flammable refrigerants (A2L and A3) made on or after Jan 1, 2017 is certified under Appendix B4, which uses AHRI 740 plus UL 1963 Supplement SB. (82.158(d)(3))
• Use recovery equipment the way the manufacturer's instructions say, unless they conflict with EPA rules. (82.156(g))
• Recovered refrigerant can go back into the same appliance or another appliance owned by the same person without reclaiming it. Once it changes owners, it must be reclaimed by an EPA-certified reclaimer to the AHRI 700 purity spec. (82.156(h), 82.154(d), 82.164)
• Hooking up hoses and gauges to read pressures, add refrigerant, or recover refrigerant is not "opening" the appliance. (82.152)

Recovery techniques that speed the job

• Recover liquid first. Liquid moves far faster than vapor. On a big system, start at the liquid side or the receiver, often with the push-pull method. In push-pull, the recovery machine pulls vapor off the recovery cylinder and pushes it into the system, which forces liquid out into the cylinder. Then switch to vapor recovery.
• Chill the recovery cylinder, for example in ice water or with the machine's cooling, and/or gently warm the system or vessel you're recovering from. Either one widens the pressure difference.
• Use short, large-diameter hoses, and take the Schrader valve cores out with a core-removal tool.
• Higher ambient temperature and a bigger recovery machine also help. Long, skinny hoses slow everything down.
• Don't mix refrigerants. Keep a dedicated, labeled cylinder for each refrigerant. When you switch the machine to a different refrigerant, pump it out, evacuate it, and change its filter-drier so you don't cross-contaminate.
• Fill cylinders to 80% at most (by liquid volume). Weigh as you go or use the cylinder's float switch. An overfilled cylinder that warms up can burst from hydrostatic pressure.
• Recovery cylinders are DOT-rated, refillable, with a gray body and yellow top. Evacuate a new or empty recovery cylinder before use to remove air. Never refill a disposable cylinder.
• NEW (AIM Act, effective Jan 1, 2028): You can't just toss an emptied disposable cylinder that held an HFC. Send it to a certified reclaimer, a refrigerant supplier, or a final processor that can remove the heel, or evacuate the heel yourself to 15 in. Hg and give the final processor a signed statement. (40 CFR 84.116) This is a separate rule from Section 608 (40 CFR 84.116). You need it on the job, but testing programs may not test it yet.

Leak detection

• Signs of a leak in a high-pressure system: high superheat, which means the evaporator is starved, and oil residue at joints and fittings. Oil travels with the refrigerant, so an oily spot usually marks a leak.
• Leak-test before you charge or recharge a system.
• The best test gas is dry nitrogen alone. Nitrogen with a trace of R-22 is acceptable as a trace gas for electronic detectors. Pressurizing with pure refrigerant is the worst choice.
• Never use oxygen or compressed air. Oxygen mixed with compressor oil under pressure can explode.
• Always put a pressure regulator and a relief valve on the nitrogen cylinder, and stay under the system's rated test pressure, which is printed on the nameplate.
• Methods that only tell you whether a system leaks, such as a standing-pressure test, sight-glass checks, receiver levels, or charging charts, have to be combined with a method that finds where it leaks. Locating methods include electronic or ultrasonic detectors, bubbles, dye with a UV light, and gas-imaging cameras. (Leak inspection definition, 82.152 and 84.102)

Leak repair rules: there are now TWO programs

This is the biggest change since the old study guides.

AIM Act leak repair: This is a separate rule from Section 608 (40 CFR 84.106). You need it on the job, but testing programs may not test it yet. In License Method practice, AIM-only questions are labeled and left out of the timed mock exam.

Here's what both programs share:

Leak-rate thresholds that trigger repair

Memory tip: "IPR 30, Commercial 20, Comfort 10."

These are the 2016-rule numbers. Before 2019 the thresholds were 35%, 35%, and 15%, so watch for old practice tests that still use them.

Calculating the leak rate. The owner or operator has to calculate it every time refrigerant is added. There are three exceptions: additions right after a retrofit, additions at installation, and additions that count as a seasonal variance. There are two allowed methods, and the same method must be used for every appliance at a facility:

• Annualizing method: (lb added ÷ full charge) ÷ (days since the last addition ÷ 365, using 365 if more time has passed) × 100. Example: you add 10 lb to a 100-lb system 73 days after the last addition. That's 0.10 ÷ 0.20 = 50%.
• Rolling average method: lb added over the previous 365 days ÷ full charge × 100. Example: a 200-lb system got 24 lb over the past year, so its rate is 12%.

Repair timeline

• Find and repair the leaks within 30 days of the refrigerant addition that showed the appliance over its threshold. IPR gets 120 days if the fix requires an industrial process shutdown.
• A certified technician has to perform the leak inspection that locates the leaks.
• Initial verification test: done after the repair, before refrigerant is added back.
• Follow-up verification test: within 10 days of a successful initial test, or within 10 days of the system reaching normal operating conditions if it was evacuated.
• Extension for unavailable parts: up to 30 days after the parts arrive, capped at 180 days (270 for IPR shutdowns) from the date the appliance went over its threshold. The extension request goes to EPA within the original 30 days (or 120). Under the AIM Act rule, it's filed electronically.
• Mothballing pauses the clock. Mothballing means evacuating to at least atmospheric pressure and temporarily shutting the system down. The clock starts again when refrigerant is added.

If the appliance can't or won't be fixed

• Write a retrofit or retirement plan within 30 days. It must be signed by an authorized company official, dated, and kept on site. Finish the work within 1 year of the plan's date.
• A request for more than one year has to be submitted within 7 months of discovering the exceedance.

Leak inspections after an exceedance

• Commercial refrigeration and IPR with 500 lb or more: inspect every 3 months until there are four quarters in a row under the threshold.
• Smaller commercial and IPR systems (50 to 500 lb for ODS, 15 to 500 lb for HFCs), plus comfort cooling: inspect once a year until there's one year under the threshold.
• A continuously monitoring automatic leak detection (ALD) system that's calibrated every year can stand in for these inspections. ALD that senses refrigerant in the air must detect 10 ppm and alert at 100 ppm. ALD that monitors system conditions must alert when the system loses 50 lb or 10% of its charge, whichever is less.
• Inspectors don't have to check components that are insulated, under ice, underground, behind walls, more than 2 meters up, or unsafe to reach.

Chronic leakers: an appliance that leaks 125% or more of its full charge in a calendar year must be reported to EPA by March 1 of the following year.

Purged refrigerant that is destroyed at 98% efficiency or better doesn't count toward the leak rate.

NEW, AIM Act extras (This is a separate rule from Section 608 (40 CFR 84.108 and 84.112). You need it on the job, but testing programs may not test it yet.)

• ALD required: commercial refrigeration and IPR systems with 1,500 lb or more of HFC (GWP above 53). Systems installed on or after Jan 1, 2026 need it at installation or within 30 days. Systems installed from 2017 through 2025 need it by Jan 1, 2027. (84.108)
• Reclaimed refrigerant mandate: starting Jan 1, 2029, supermarket systems, refrigerated transport, and automatic commercial ice makers that use HFCs must be serviced with reclaimed HFC. (84.112(e))
• Reclaim purity: starting 2026, refrigerant sold as "reclaimed" can contain no more than 15% virgin HFC. (84.112(a))
• Pending: in May 2026, EPA proposed exempting road and intermodal transport refrigeration units from 84.106 and said it will reconsider the rest of the 2024 ER&R rule. Until a final rule changes the text, study the current rule.

Quick classification examples

• A 30-lb R-22 walk-in: no federal leak-repair duty. It's under 50 lb for 82.157, and 84.106 excludes systems that contain only ODS.
• A 20-lb R-404A walk-in (GWP 3,922): covered by 84.106 since Jan 1, 2026, with a 20% threshold.
• A 5-ton residential R-410A split: excluded from 84.106, since it's residential and light commercial A/C. Venting, recovery, and certification rules still apply.

Recordkeeping (3 years unless noted)

• Owners of covered appliances (50 lb or more for ODS, 15 lb or more for HFCs) keep the full charge and how it was figured, service records, leak-rate calculations, leak inspection results, verification tests, and retrofit plans. Full-charge records are kept until 3 years after the appliance is retired.
• The technician who adds or removes refrigerant must give the owner documentation: the appliance, the date, the work done, the tech's name, and the amount and type of refrigerant added or removed.
• Disposal of appliances holding more than 5 and less than 50 lb: the technician records the company name, appliance location, date, and refrigerant type for each appliance; the monthly totals recovered; and where refrigerant was sent for reclamation or destruction, with dates. (82.156(a)(3))

The refrigeration cycle on the exam

• The receiver stores liquid, so it's a good place to recover liquid from.
• The accumulator sits in the suction line and keeps liquid from slugging the compressor.
• The filter-drier in the liquid line removes moisture, acid, and dirt. A sight glass with a moisture indicator shows liquid flow and how wet the system is.
• psia = psig + 14.7. PT charts read in psig, and EPA's pressure classes use psia.
• To identify the refrigerant, read the nameplate, then compare the standing pressure to the PT chart at a known temperature. If an idle system reads higher than the PT chart at ambient temperature, it probably has non-condensables (air).
• Zeotropic blends (the 400 series, like R-407C and R-454B) have temperature glide and can fractionate. Charge them as liquid (metered so it flashes before reaching the compressor) unless the manufacturer says otherwise.

Evacuation (dehydration) before charging

After a system has been opened, pull a deep vacuum to remove air and moisture.

• Use a vacuum pump sized for the system, with short, large-diameter hoses. Read the vacuum with a micron gauge at the system, not at the pump.
• 500 microns is the common industry target. EPA doesn't set a micron level.
• Warming the system speeds up dehydration.
• Never energize a hermetic or semi-hermetic compressor while it's under a deep vacuum. The motor windings can short or arc.

Safety

• Refrigerant vapor is heavier than air and pushes out oxygen. In basements, pits, and mechanical rooms, it can cause asphyxiation. Breathing high concentrations can also cause heart arrhythmias.
• A flame or hot surface breaks refrigerant down into toxic acids: hydrochloric and hydrofluoric acid, and phosgene from chlorinated refrigerants. Ventilate before you braze.
• Liquid refrigerant causes frostbite. Wear safety glasses and gloves, and use SCBA for big releases in enclosed rooms.
• ASHRAE Standard 15 sets rules for equipment rooms. EPA's test topics specifically mention the oxygen-deprivation sensor (required with all refrigerants), along with refrigerant detectors, alarms, and mechanical ventilation.
• A2L refrigerants (R-32, R-454B, R-1234yf) are A = lower toxicity, 2L = lower flammability, with a slow flame speed. Use recovery machines, vacuum pumps, and detectors rated for A2L refrigerants. Keep ignition sources away, ventilate, follow the equipment's refrigerant-detection and mitigation instructions, and never put a flammable refrigerant into a system that wasn't designed for it. Hydrocarbons are not approved as retrofits.
• AHRI Guideline N marks flammable-refrigerant containers with a red band. A2L cylinders may also have left-hand-thread valves that need an adapter, so check before you connect.

HFC technology transitions: what you can install (AIM Act, 40 CFR 84.54)

This is a separate rule from Section 608 (40 CFR 84.54). You need it on the job, but testing programs may not test it yet.

• New residential and light commercial A/C and heat pumps manufactured or imported from Jan 1, 2025 on must use refrigerant with a GWP under 700. That rules out R-410A (GWP 2,088) and leaves R-454B (465) and R-32 (675).
• CHANGED (May 2026 final rule, effective July 27, 2026): R-410A residential and light commercial systems whose specified components were all made or imported before Jan 1, 2025 can still be installed, with no end date. The earlier Jan 1, 2026 cutoff is gone.
• VRF systems have a GWP 700 limit for installation starting Jan 1, 2026. Systems whose components were made before 2026 could be installed until Jan 1, 2027.
• Other installation limits: comfort-cooling chillers have a 700 limit from Jan 1, 2025. Supermarket systems have a 1,400 limit from Jan 1, 2027, and remote condensing units have a 1,400 limit from July 27, 2026, with tighter 150 and 300 limits in 2032.
• Equipment covered by these rules has to carry a permanent label showing the refrigerant and its date of manufacture. For field-charged systems, the label is completed at the first charge. (84.58)
• Background: the AIM Act (Dec 27, 2020) phases HFC production and consumption down 85% from baseline by 2036.

Rapid-fire numbers to memorize