The Complete Guide for HVAC Leak Sealing
Small leaks, big problems. If your air conditioner or heat pump is losing refrigerant, it means higher energy bills, poor cooling, and costly repairs. That’s where Enviro-Safe® ProSeal XL4 Direct Inject comes in — a professional-grade sealant trusted by HVAC technicians worldwide.
🔹 What Is ProSeal XL4?
ProSeal XL4 is a concentrated, one-time-use cartridge that connects to your system’s low-side service port. Once released, it flows with the refrigerant, finding and sealing pinhole leaks from the inside.
It works in:
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Heat pumps
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Split and mini-split units
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Packaged systems
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Microchannel coils
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Coolers & commercial systems
🔹 How Does It Work?
The sealant travels with refrigerant throughout the system. When it reaches a leak, exposure to air/moisture causes it to harden, forming a durable seal on:
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Condensers & evaporators
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Schrader valves
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O-rings & gaskets
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Line sets & solder joints
Think of it as a stop-leak for your A/C system — but professional-strength.
🔹 Why Choose ProSeal XL4?
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⚡ Travels with refrigerant — finds hidden leaks faster
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🔒 Forms a permanent seal on small pinholes and joints
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❄️ No pump-down required (saves time on R410A & others)
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🛠️ One-time, easy inject — no hoses or caulk guns needed
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🌍 Lowers emissions & refrigerant loss
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📈 Backed by 17+ years of proven performance
🔹 Step-by-Step: How to Install
⚠️ For professional use only.
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Turn system on and confirm it’s running.
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Connect injector to the low-side service port (large line).
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Purge air from the manifold hose before releasing.
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Open low-side valve and allow sealant to flow (only takes seconds).
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Close valve & disconnect once the tube clears.
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Run system for at least 1 hour to circulate and activate the sealant.
👉 Pro tip: Some techs inject a drying agent beforehand to maximize sealing success.
🔹 FAQs
Q: What size leaks can it fix?
A: ProSeal XL4 works best on small pinhole leaks. Large ruptures still need mechanical repair.
Q: Is it safe for microchannel coils?
A: Enviro-Safe lists microchannel as compatible, but some manufacturers advise caution. Always check OEM guidance.
Q: Will this void my warranty?
A: Some OEMs prohibit additives and may deny warranty claims. Always confirm before use.
Q: DIY or professional only?
A: This is a professional-use product. If you’re not experienced with refrigerant systems, hire a licensed HVAC technician.
🔹 Safety First
Like all sealants, ProSeal XL4 contains flammable liquids (ethanol, toluene, silanes). Handle carefully:
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🔥 Keep away from sparks/open flames
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🧤 Wear gloves, goggles, and protective clothing
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🌬 Use only in ventilated areas
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♻️ Dispose of containers properly
⚠️ California Proposition 65 Warning: Contains Toluene, which is known to cause birth defects or other reproductive harm.
🔹 Final Takeaway
ProSeal XL4 Direct Inject is one of the most advanced HVAC/R sealants on the market. It’s designed to:
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Stop leaks before they become disasters
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Extend equipment life
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Save refrigerant, money, and energy