HVAC TIP: Refrigerant Leak Checking Procedure.

Key Takeaways

• Verification First: Always confirm a leak exists through pressure readings and superheat/subcooling analysis before beginning repairs
• Visual + Electronic Detection: Combine visual inspection for oil residue with electronic leak detectors for accurate leak location
• Common Leak Points: Focus on threaded fittings, Schrader cores, valve stems, and flares before checking brazed joints
• Safety Critical: Always verify Schrader cores aren’t stuck open after gauge attachment to prevent creating new leaks

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Refrigerant leaks are the bread and butter of HVAC service work – they’re incredibly common and keep technicians busy year-round. Whether you’re dealing with a residential split system or a commercial rooftop unit, having a systematic approach to leak detection saves time and ensures you don’t miss anything.

Let’s walk through the complete refrigerant leak checking procedure step by step.

1. Verification: Confirming You Actually Have a Leak

Before breaking out the leak detector, you need to verify that a leak is actually present. This crucial first step prevents unnecessary work and misdiagnosis.

Attach your gauges to the system’s service ports. If your gauges read zero pressure, you’ve got an obvious leak situation – the system has lost its entire charge.

However, if the system is still holding some refrigerant, you’ll need to do some detective work. Other issues like restrictions can mimic the symptoms of a low charge. This is where your superheat and subcooling readings become invaluable diagnostic tools. Abnormal readings that indicate low refrigerant charge – high superheat on fixed orifice systems or low subcooling on TXV systems – point toward a leak rather than other system problems.

2. Visual Inspection: Looking for the Tell-Tale Signs

Once you’ve confirmed a leak exists, conduct a thorough visual inspection of the entire system. Oil residue is your best friend here – it’s a reliable indicator of potential leak locations since refrigerant oil escapes along with the refrigerant.

Check these areas carefully:

• Service valve caps and connections
• Evaporator and condenser coil surfaces
• Compressor terminals and body welds
• All visible refrigerant line connections
• Filter drier connections

Don’t forget to seal your service valve caps properly after servicing – they’re a common source of slow leaks that technicians often overlook.

3. Adding Nitrogen for Empty Systems

If the system has completely lost its charge, nitrogen testing is your next move. Add dry nitrogen to the system at the manufacturer’s recommended test pressure (typically 150-250 PSI depending on the system).

Apply a quality leak detection soap like Viper Big Blu to all potential leak points and watch for bubbles. Start with the usual suspects:

• Threaded fittings
• Schrader cores
• Valve stems
• Flare connections

These mechanical connections tend to leak more frequently than brazed joints, so checking them first is the most efficient approach.

4. Electronic Leak Detection for Charged Systems

When the system still contains refrigerant, electronic leak detection is your most effective tool. A quality electronic leak detector like the Testo 316-3 can pinpoint even small leaks quickly.

Here’s the proper technique:

1. Move the probe slowly (2-3 inches per second)
2. Start at the highest point and work downward (refrigerant is heavier than air)
3. Check all joints, connections, and components systematically
4. Once you detect a leak, verify the exact location with soap bubbles

5. Communicate With the Customer

After locating and verifying the leak, clear communication with your customer is essential. Explain:

• The leak location and severity
• Repair options and associated costs
• The environmental impact of refrigerant leaks
• Timeline for repairs

This is also a good time to discuss preventive maintenance that could help avoid future leaks.

Important Considerations and Pro Tips

Watch Those Schrader Cores

Schrader cores are notorious leak points. Always check them before and after attaching your gauges. Here’s why: these cores can stick open after you remove your gauges, creating a new leak where none existed before. Keep a core removal tool handy and replace any questionable cores.

Don’t Skip These Often-Missed Areas

Experience has taught us to check these commonly overlooked locations:

• Compressor body welds (especially on older units)
• Wiring penetrations on encapsulated pressure switches
• Indoor evaporator coils hidden behind insulation
• Service valve packing glands

When to Consider Refrigerant Dye

While some technicians avoid refrigerant dye entirely, it can be a valuable last resort for intermittent or extremely small leaks. If you use it:

• Add the manufacturer’s recommended amount only
• Document the addition for future technicians
• Warn the customer about potential oil staining
• Use UV light and glasses for detection

Planning Your Next Steps

Once you’ve found the leak, you’ll need to plan the repair carefully. For systems requiring extensive repairs, consider discussing the benefits of understanding the refrigeration cycle with newer technicians on your team – it helps them understand why proper evacuation and charging procedures are critical after leak repairs.

Finding the leak is just the beginning. Property.com’s ‘Know Before You Go‘ tool helps you arrive prepared with complete property history and homeowner insights, allowing you to quote repairs accurately and build trust from the first interaction. Top HVAC pros use Property.com to streamline their service calls and grow their business through better customer relationships.

Conclusion

A systematic approach to refrigerant leak detection saves time, prevents callbacks, and ensures customer satisfaction. Remember that finding the leak is only half the battle – proper repair techniques, including proper system evacuation procedure and accurate charging, are equally important for a complete repair.

By following this procedure and paying attention to the commonly missed areas, you’ll catch leaks that others might miss and build a reputation for thorough, professional service.

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