No Leaks, No Problems: How to Pressure Test and Leak Check Your 5-Ton R-32 HVAC System Like a Pro

🎤 Intro: If It Leaks, It Ain’t Cooling – Mark’s Hot Take

Hey there, fellow tech nerds and hands-on homeowners. Mark here.

Now look—I love high-efficiency HVAC systems. I love R-32 for what it brings to the table. But what I don’t love? Leaks. Especially on a 5-ton system where one tiny flare fitting gone wrong can dump pounds of refrigerant into the ether (or worse, into your basement). I’ve seen systems undercharged by half a pound and still run—for a while. Then they fail like a college kid with a hangover at a 9 a.m. final.

So if you're setting up one of these big ol’ 5-ton R-32 combos, pressure testing and leak checking aren’t optional. They're required. Not for the inspectors, not for the warranty, but for your own sanity.

Today I’m walking you through exactly how to do it right—from nitrogen pressure tests to bubble checks to what kind of leak detection tools are actually worth your paycheck.

Let’s plug the holes and protect your investment.

 

🧪 Why Pressure Testing Is Non-Negotiable for R-32 Systems

Let’s get this out of the way: R-32 is highly efficient but slightly flammable. It’s not napalm, but it does deserve respect.

And because it operates under higher pressures than R-22 or even R-410A, even the tiniest leak can cause:

• Compressor failure

• Decreased cooling performance

• Increased electric bills

• Moisture contamination

• Major safety risks in enclosed spaces

And no—charging your system and seeing frost on the line set isn’t good enough. You need to verify the system is sealed before you even think about vacuuming and charging.

Need backup? The EPA’s official refrigerant practices clearly state leak testing is required for all systems over 5 pounds of refrigerant. Your 5-ton system? Easily double that.

 

🧯 What You’ll Need Before You Begin

Here’s the tool list. Don’t cut corners.

• Nitrogen tank with a regulator (rated up to 500 psi)

• Pressure gauges rated for high-pressure refrigerants

• Soapy water spray, or leak bubble solution

• Optional: Electronic leak detector (sniffer)

• Optional: Ultraviolet dye kit

• Safety glasses and gloves

• Core removal tools and Schrader valve depressors

If you want gear that won’t break mid-job, check out Fieldpiece or UEi Test Instruments. They're pro-grade and worth every penny.

Also: if you don’t own nitrogen, rent it. NEVER pressure test with compressed air or oxygen. That’s how you end up on the news.

 

🧷 Step 1: Pressure Test with Nitrogen – The Gold Standard

This is the step every manufacturer recommends—and most DIYers skip. Don’t be that person.

Here’s how to do it:

1. Isolate the system by closing service valves

2. Remove Schrader cores (use a core tool, don’t just poke around)

3. Connect nitrogen tank and pressurize to 300–350 psi

4. Close the valve and let it sit for 30–60 minutes

5. Watch your gauges. No pressure drop = good. Even a 1–2 psi loss? Bad.

Need a cheat sheet? HVAC School has a great walkthrough with real-world numbers.

Pro tip: I always record the test start time and end time. If pressure drops, don’t assume it’s your gauge. Use a second one to confirm.

 

🫧 Step 2: Leak Check with Bubble Solution – Old School, Still Works

Once you're pressurized, break out the bubbles.

• Spray every braze joint, flare fitting, Schrader valve, and TXV nut

• Watch closely for slow-growing bubbles

• If you see foam or froth? You’ve got a leak

• Tighten or re-braze as needed, then re-pressurize and retest

Use something made for HVAC like Big Blu—not dish soap. Cheap soap can corrode fittings over time, believe it or not.

Some techs scoff at bubbles, but I once found a TXV leak that three sniffers missed—just by catching one tiny bubble near a cap tube. Eyes > electronics, sometimes.

 

🐍 Step 3: Using an Electronic Leak Detector – The High-Tech Approach

I love sniffers—but they’re not magic.

Here’s how to use one right:

• After your nitrogen test (and bubble test), charge with a few ounces of R-32

• Turn off airflow—leaks are easier to detect in still air

• Pass the sniffer slowly over each joint and fitting

• Let the sensor stabilize before moving between points

Look for models rated for A2L refrigerants. My go-to is the Fieldpiece DR82—super accurate and doesn’t false-alarm like the cheap Amazon ones.

🔦 When and Where Leaks Most Often Happen

After 20+ years on the job, I can tell you where 90% of leaks happen:

• Flare fittings (especially when not torqued properly)

• Braze joints (bad purge technique)

• Capillary tubing and TXVs

• Schrader cores and valves

• Line set connections at wall penetrations

• Evaporator coil distributor tubes

Make it a habit to inspect these areas even on brand-new equipment. Factory connections are not infallible.

 

🧰 Fixing a Leak? Do It Right or Don’t Do It At All

Here’s how to do proper leak repair:

• For flared connections: Cut, reflare with R-32 rated tool, torque to spec

• For braze joints: Purge nitrogen, clean thoroughly, re-braze with 15% silver solder

• For valve cores: Replace with new cores and torque caps

Then—yes—repeat the full pressure test. No exceptions. If it passed before and fails now, something else got bumped during repair.

And remember: R-32 is single component, so no need to worry about fractionation like R-410A. Just evacuate, repair, and recharge to factory specs.

 

🧠 Mark’s Myth-Busting: “It Holds Vacuum, So It Must Be Leak-Free”

Wrong. A system can pass a vacuum test and still fail pressure testing. Why?

• Vacuum pulls in, while pressure pushes out

• Some leaks only show under pressure

• Moisture and contaminants might seal a leak during evacuation

Bottom line: you must pressure test with nitrogen. No shortcuts, no excuses. The vacuum phase comes later—for drying the system.

And if you want more on vacuum myths, check out this excellent breakdown from Bryan Orr at HVAC School.

 

🛠️ Final Charge and Seal: Only After It’s Leak-Free

Once your system is verified sealed:

1. Pull a vacuum to at least 500 microns, ideally 300

2. Break vacuum with dry R-32 vapor

3. Charge to exact factory weight (use a digital scale)

4. Log your readings: suction, discharge, superheat, subcooling

Then and only then do you button it up and consider it “done.”

Want to see manufacturer specs for Goodman’s R-32 systems? They’re usually printed right on the data plate, or check the Goodman website for PDF install manuals.

 

🧢 Outro: No Pressure, All Precision – Mark’s Final Thoughts

If you skipped to the bottom hoping for a shortcut, let me stop you right there.

There are no shortcuts in leak testing. Not with R-32. Not with 5-ton systems that cost more than my first used pickup. One sloppy joint, one half-hearted sniff test, and you could be losing performance—and hundreds of bucks in refrigerant—every single month.

Here’s what I want you to remember:

• Pressure test first

• Bubble test everything

• Trust sniffers and your eyeballs

• Don’t let “good enough” be the enemy of “sealed tight”

You wouldn’t build a boat with holes in it. Don’t build an HVAC system that leaks from Day 1.

If you’re still shopping for a system, or you just want a model that’s been engineered with leak-resistant components and solid documentation, I always send folks to The Furnace Outlet’s 5-ton R-32 lineup. These systems are built for real-world installs and come with the paperwork to back you up on every spec.

Need some more troubleshooting tips? Visit my guide: When the Heat Cuts Out.

Stay sealed. Stay sharp. And if you ever wonder whether to bubble test “just one more time”—the answer is yes.

Until next time,
– Mark Callahan 🧢🛠️
"Still looking for leaks... and still not trusting that one flare fitting you swore was tight."