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Vacuum Not Holding

Wobbly007 on Sun September 09, 2012 5:18 PM User is offline

Year: 1992
Make: Honda
Model: Accord
Refrigerant Type: R-134a
Country of Origin: United States

Just replaced the expansion valve and receiver-drier. Pulled a vacuum for about half an hour. The manifold gauges are pegged with the pump running, but drop down to near zero in a few minutes after the pump is shut off. The evaporator case was full of leaves and in a lapse of judgement I sprayed the coil with a water hose without plugging the open lines. I let the evaporator case out in the sun for a few hours and then ran compressed air through the evaporator to purge the water and contaminated oil. I then added 10 ml of PAG oil to the evaporator. New o-rings were installed at evaporator, expansion valve, and receiver.

There's a steady stream of vapor in the pump exhaust with the ballast valve open.

Will running the vacuum pump for a longer time eventually result in clear exhaust stream and a dry system which holds a vacuum?

mk378 on Sun September 09, 2012 6:08 PM User is offline

If it were just water contamination, the vacuum wouldn't drop all the way to zero. There is a leak. Testing under pressure should reveal it especially if it is under the hood and not one of the connections in the evaporator box.

Edited: Sun September 09, 2012 at 6:10 PM by mk378

Wobbly007 on Sun September 09, 2012 7:48 PM User is offline

The manifold set was disconnected from the system and then evacuated fully. After the manifold valves were closed the gauges leaked down rapidly.
What's a good way to find the leak?


Edited: Mon September 10, 2012 at 7:43 AM by Wobbly007

Wobbly007 on Tue September 11, 2012 9:08 PM User is offline

Problem was the gauge manifold push-on couplers. When 150 psi nitrogen was applied to the system, I could hear the couplers leaking. Looked like they couldn't be repaired, so I bought a set of Santech replacements for a hefty price.

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