New poster that needs guidance

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Mr.
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Joined: Thu Jun 18, 2020 8:17 am

New poster that needs guidance

Postby Mr. » Thu Jun 18, 2020 10:13 am

Hello, I replaced all the a/c components in my van in 2015 due to a compressor failure. It's been working great ever since (40* at the vent). But recently it started blowing warm. So I put 3 lbs of freon back in and all was good. But when I took the high pressure hose off the van after filling. The ball valve stayed open and I had to use the cap to stop the freon from coming out. Yikes!! Anyhow, so I figured that was where my very slow leak was at. Then 3 days later I had to remove the air breather so I could replace the serpentine belt. That's when I noticed the freon had been leaking out around the compressor shaft seal. OK, so I ordered a new compressor of the same type and a new a/c line with ball valve. Installed new line. When I went to drain leaking compressor of oil, there was no oil which I expected. So I put in the 2 oz as per the manual but added a 1/2 ounce extra just in case more oil had leaked out. Put it back together. Vac and fill. The coldest it would get was 50*. So I figured that extra 1/2 ounce was to much cause I've added to much in the past and it didn't cool as well. So I decided to take that 1/2 ounce of oil out of the compressor so it would cool properly. But I was shocked to see no oil in the compressor after just putting 2.5 ounces in it 3 days earlier.

Shouldn't there always be oil, up to 2 ounces that stays in the compressor? If that's the case, does this mean I did not have enough oil in the compressor and that's why there was no oil in it the second time? So now I've added a total of 4.5 ounces to the compressor. The system holds 8 oz. The a/c is blowing cold now like it should, 40* at the vent. But I'm wondering, should I pull the compressor back off and see if there's any oil in it considering it is blowing cold? Or should I leave it alone? I just don't want to have a compressor failure and have to start all over again like in 2015. Thank you for any advice received.
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JohnHere
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Location: South Carolina Upstate - USA

Re: New poster that needs guidance

Postby JohnHere » Thu Jun 18, 2020 6:24 pm

Let's begin with the year, make, and model of your vehicle, which I don't think you mentioned yet, and we'll go from there.
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Tim
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Re: New poster that needs guidance

Postby Tim » Thu Jun 18, 2020 7:41 pm

Operational pressure readings would be helpful.

Unless you have an oil sump. The oil moves through the system carried by the refrigerant.
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Al9
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Joined: Tue Mar 10, 2020 3:26 am

Re: New poster that needs guidance

Postby Al9 » Fri Jun 19, 2020 2:26 am

Oil begins accumulating in the coldest part of the system, the evaporator (where it gets the coldest and hence the thickest and hardest to move around, also taking into consideration that evaporators need to have the largest internal heat exchange surface as possible; PAG 46, the thinnest auto AC oil available, is the preferred oil for this very reason), as soon as the refrigerant charge gets low enough. Even though it's sumpless, the compressor will retain the nominal oil amount as long as the system has proper oil return. Restrictions, low refrigerant, bad TXV operation, bad plumbing design (especially with rear evaporator systems) is what interferes with proper oil return.
Mr.
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Joined: Thu Jun 18, 2020 8:17 am

Re: New poster that needs guidance

Postby Mr. » Fri Jun 19, 2020 4:54 pm

Hello, it's a GMC Savana 6.5l. It has the Delphi cs0121 Ht6. It sounds like theirs no real way to know how much oil I should have put back in. When I repaired it in 2015, my manual said to put certain amounts of oil in each component so I assumed each component kept that amount of oil in it. It was 83* outside and the low side was 30, high side 145.
Al9
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Joined: Tue Mar 10, 2020 3:26 am

Re: New poster that needs guidance

Postby Al9 » Sat Jun 20, 2020 3:51 am

The Sanden made replacement is way better. Better lubrication system design. Better seals.

Actually, during system operation, the oil content of each component varies according to heat load and engine speed... even in a properly charged system the compressor tends to retain less oil as RPM increases... whenever it's instructed to distribute oil across the system upon installation, it's only to encourage a better oil return during the run-in phase. Especially, in orifice tube systems, oiling of a new accumulator is critical. It's the first thing the new compressor will be drawing oil from and its ability to replenish whatever the sumpless compressor discharged during startup is critical.

With sumpless comps, there's no real way to know if the system has a proper oil charge except getting the compressor off, draining any oil from it and flushing everything, then filling the proper oil amount in.

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