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honda ac won't hold a vacuum unless I disconnect a tube and hold with my fingers?! huh?

willpower101 on Sat August 21, 2010 6:42 PM User is offline

Year: 1992
Make: honda
Model: civic
Engine Size: 1.5
Refrigerant Type: r134a
Ambient Temp: na
Pressure Low: na
Pressure High: na
Country of Origin: United States

So i swapped engines a few months ago and the system is bone dry.
I changed o-rings when i put the compressor back on.
Pulled a vacuum with a 1.5cfm vac and manifold gauges from autozone.
Close the gauges, let it sit.
Withing 60s the pressure returns from -29hg to almost 0.

I've been trying to locate this massive leak.

out of curiousity I disconnected the hose going between the evaporator and the condensor.
(not the large low side hose, the small hose #14 in this picture)

When I manually put my fingers over both ends where i disconnected it, not only just it hold a vacuum after I seal the gauges off, it holds a good strong one that almost hurts my fingers.

What in the world could be causing this??? (i tried installing a seal here (doesn't take one) and even manually holding it together.)

mk378 on Sat August 21, 2010 7:35 PM User is offline

There should be an o-ring (part #25) in the groove on the "peanut" fitting at the evaporator end.

willpower101 on Sun August 22, 2010 1:27 PM User is offline

willpower101 on Sun August 22, 2010 1:31 PM User is offline

No go. No matter what I try right there I can't seem to get it to work.

When I use my fingers to stop the air, the pressure does fall, just Reaaaaaaally slow, (i'm assuming my fingers are leaking)

When i use any combination of o-rings on that connector, the pressure drops quick and steady.

I know this sounds crazy, but is there any way that when that's connected it's causing it to leak somewhere else, and when it's separated by my fingers it's changing the pressure in different areas causing it to leak slower?

mk378 on Sun August 22, 2010 2:55 PM User is offline

It almost has to be leaking there. When the compressor is not running, the whole system equalizes to the same pressure or vacuum. You could confirm by putting the system under positive pressure with a little R-134a, then use an electronic leak detector or soap bubbles.

Check the o-ring groove on the fitting and the bore of the block on the evaporator for corrosion or other damage.

willpower101 on Sun August 22, 2010 5:14 PM User is offline

I'm almost wondering if I should just take it to a shop. I haven't opened any of my supplies yet except the gauges and pump which are loaners.

So basically, I have 2 cans of normal fluid, 1 can of pag 46, 1 can of UV to waste testing for leaks, new retrofits cause the old ones' seals went bad (i'm plugged directly into the r12 fittings right now). new valve cores, o-rings, and I will need to buy a receiver/drier. All of that has put me at 105$. The liquids themselves are about 60 from autozone.

At least a shop would be able to find the leak, seal everything back up, and probably replace the drier at no extra charge if I give them the part.
Worst case scenario is that the compressor is leaking also.

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