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System Evacuation

mad_trbo on Fri September 18, 2009 1:32 PM User is offlineView users profile

Year: 1987
Make: Buick
Model: Grand National
Engine Size: 3.8
Refrigerant Type: r134a

Two Questions for the experts.

If when hooking up the manifold gauge to my Regal, I see no pressure on either side. Is it still necessary from a refrigeration stand point to evacuate the system? Or has all refrigerant leaked or left the "closed" system.

If the system has been opened and I have the ability to pull vacuum down to 28 - 30 inhg. Is it necessary to purchase a new accumulator? Or will pulling the vacuum rid the system of all moisture.

Thanks in advance for any assistance!

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1993 GSX Eclipse - This is the small Stick
1987 Buick Grand National - This is the big stick if you take out the Eclipse which is rare

Chick on Fri September 18, 2009 2:26 PM User is offlineView users profile

Since this is a conversion, a new accumulator is needed, and yes, you must pull a deep vacuum, use the proper oil for R134a and then recharge into the vacuum..

Parts for 87 Buick regal with 3.8

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

mk378 on Fri September 18, 2009 2:57 PM User is offline

What history do you know of this car? Has it been properly converted? Generally when you find zero pressure, assume there is a leak. Make a visual inspection for anything obvious. Then put in some nitrogen and/or R-134a and check for leaks. The drier should always be replaced on a car that has been sitting around with zero pressure.

mad_trbo on Fri September 18, 2009 6:13 PM User is offlineView users profile

I should have been a bit clearer.

The original conversion was performed by the dealership. I have since then rebuilt the engine, during the rebuild the the entire a/c system was pulled, but it had already been converted to 134a by Buick themselves.

I purchased a new compressor even though there was nothing wrong with the old compressor. I did this under the premise that I wanted everything to be brand new, power train, accessories, alternator etc......

While this is the case, I put the car back together, pulled a deep vacuum and charged through vacuum. I immediately heard a hissing noise where the lines bolt to the compressor. It turns out I used the wrong sealing washer, I have since corrected this error placed the system under deep vacuum again and let it sit for an eight hour period with no change in the vacuum reading.

So now I want to know with zero pressure reading, because it all leaked out the back of the compressor do I need to reclaim or recover anything before charging? I am assuming anything that might have been a liquid was changed to a gas. So there is nothing to reclaim, so can I give the system a full charge again?

My other question is how much oil should I have put in the compressor which had none when I purchased it!!

Thanks again

-------------------------
1993 GSX Eclipse - This is the small Stick
1987 Buick Grand National - This is the big stick if you take out the Eclipse which is rare

mk378 on Fri September 18, 2009 10:28 PM User is offline

When a system has leaked down to zero you don't have to reclaim. Attempting to reclaim will just suck a bunch of air through the leak and contaminate your recovery tank. After opening a system to make repairs, the pressure will be zero so simply evacuate and charge it.

If you're sure there is no oil in the compressor and you have replaced the accumulator, that only leaves the lines, evaporator, and condenser, which typically don't trap a lot of oil. So put in nearly the full system charge worth of oil.

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