Said It Here

Cool air leaking from gap around AC copper pipe in attic

An unsealed gap where the copper refrigerant line enters an attic AC unit allows conditioned air to escape, creating a noticeable cool breeze in a hot space. Homeowners frequently discover this opening while changing filters and wonder whether it indicates a system malfunction or a harmless non-issue.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    throwing some foil tape on it to block airflow
  2. 2
    sealing that gap with something called Plumber's putty or Thumb-gum
  3. 3
    using cork tape to seal it
  4. 4
    Changed the seal on the vacuum gauge
  5. 5
    Pressure tested fittings, gauges, and core remover
  6. 6
    Sprayed everything with bubbles
  7. 7
    Bypassed the manifold completely and went directly from the unit to the vacuum pump
  8. 8
    Put the system back under nitrogen to check for pressure loss over a few days

In their words

Unedited, most upvoted first, each linked to the thread it came from.

“We bought this house and moved in about a year ago. Today my husband was in the attic to change the air filters (two AC units) and he noticed a gap where this copper pipe is going into one of the units.”source ↗

“He tried sticking his finger near/ into the gap and felt a light cool breeze coming out (it's pretty hot in the attic, so easy to tell that there's a cool breeze coming out).”source ↗

“It just seems odd so we're curious if this is something that should be checked out or a non-issue.”source ↗

justdointhingsnstuff · r/hvacadvice · 1 upvotes

“On my last few AC installs, my vacuum seems to hit a wall at around 650–700 microns.”source ↗

“Today I pulled a system down and the lowest I could get was about 660 microns.”source ↗

“I isolated the vacuum pump and watched the micron gauge. It rose from roughly 660 to around 800 microns, but then stabilised and held around than continuied to creep up.”source ↗

“I keep getting stuck around the same 650–700 micron range, which is making me think it might be something in my evacuation setup rather than every system having the same issue.”source ↗

Strong-Wrongdoer8332 · r/hvacadvice · 1 upvotes

Where this came up

r/hvacadviceair conditionerhome maintenancehvactoolstroubleshooting

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