Uploaded July 2026 | Updated September 2026, 3 weeks ago
Why does a compressor fail months after a routine install, with no obvious cause? In this video, Ty Branaman walks through the chemistry most techs skip past: what actually happens inside the system when moisture gets left behind.
Pulling a proper vacuum is the one step you can't go back and redo later — you can fix ductwork, you can reseal a flare, but you can't undo moisture that's already been sealed into the lines. The reason it matters so much comes down to POE oil. It's a fantastic lubricant and great at heat transfer, but introduce even a small amount of moisture and that oil slowly converts to acid.
That acid doesn't stay contained — it eats away at copper, opening up pinhole leaks in the coil. The etched copper then travels through the system and lands on the hottest part of the compressor, building up as plating on internal moving parts. Over time, that buildup increases friction, raises amp draw, and makes startup harder. Techs often blame a "weak motor" or reach for a hard start kit, when the real culprit is copper plating slowly choking the compressor from the inside — a process that ends the same way every time: failure.
Topics covered in this video:
Why a deep vacuum can't be skipped or rushed
How moisture converts POE oil into acid
Acid's effect on copper lines and pinhole leaks
How copper plating builds up inside compressors
Why "weak motors" are often actually copper plating
Decay testing and why it matters
Read all the tech tips, take the quizzes, and find our handy calculators at hvacrschool.com or the HVAC School Mobile App on the Google Play Store (hvacrschool.com/play-store) or App Store (hvacrschool.com/app-store).
Why does a compressor fail months after a routine install, with no obvious cause? In this video, Ty Branaman walks through the chemistry most techs skip past: what actually happens inside the system when moisture gets left behind.
Pulling a proper vacuum is the one step you can't go back and redo later — you can fix ductwork, you can reseal a flare, but you can't undo moisture that's already been sealed into the lines. The reason it matters so much comes down to POE oil. It's a fantastic lubricant and great at heat transfer, but introduce even a small amount of moisture and that oil slowly converts to acid.
That acid doesn't stay contained — it eats away at copper, opening up pinhole leaks in the coil. The etched copper then travels through the system and lands on the hottest part of the compressor, building up as plating on internal moving parts. Over time, that buildup increases friction, raises amp draw, and makes startup harder. Techs often blame a "weak motor" or reach for a hard start kit, when the real culprit is copper plating slowly choking the compressor from the inside — a process that ends the same way every time: failure.
Topics covered in this video:
Why a deep vacuum can't be skipped or rushed
How moisture converts POE oil into acid
Acid's effect on copper lines and pinhole leaks
How copper plating builds up inside compressors
Why "weak motors" are often actually copper plating
Decay testing and why it matters
Read all the tech tips, take the quizzes, and find our handy calculators at hvacrschool.com or the HVAC School Mobile App on the Google Play Store (hvacrschool.com/play-store) or App Store (hvacrschool.com/app-store).
