Black oil on orifice tube

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72gmc4x4
Posts: 42
Joined: Wed May 04, 2016 11:19 pm

Black oil on orifice tube

Postby 72gmc4x4 » Thu Jun 08, 2017 9:14 am

The orifice tube is covered in black oil but free of debris. Does that indicate a failing compressor?

2000 Chevy Tahoe with dual ac. 200k miles. The Ac wasn't working well. I found it was leaking from valve. Pressure tested and no other leaks found. When filling by weight (44oz) it took forever to fill. 45 minutes or so using a 30lb can with manifold gauges. I assumed restriction. Took the orifice tube out and it was free of debris but black in color from oil.
Dougflas
Posts: 190
Joined: Mon Apr 18, 2016 6:10 pm

Re: Black oil on orifice tube

Postby Dougflas » Thu Jun 08, 2017 12:11 pm

Oil should not be a problem. I charge by weight also from a 30 lb drum. I run a vacuum and put R134a in as liquid with engine OFF. I at this time have both hand wheels open. When no longer getting refrigerant to go in, I close high side hand wheel and low side hand wheel. I wait a few minutes, start engine, and continue charging low side only. I put in refrigerant as liquid very carefully and slowly. If vehicle has an accumulator, I am not worried about introducing liquid as the accumulator will protect compressor. When proper charge is done, I close hand wheel. It should not have taken you 45 minutes to charge the vehicle. 5 or 10 minutes at the most.
72gmc4x4
Posts: 42
Joined: Wed May 04, 2016 11:19 pm

Re: Black oil on orifice tube

Postby 72gmc4x4 » Thu Jun 08, 2017 12:44 pm

Thanks for the reply. It's never taken me that long to charge on other vehicles. I also added refrigerant while car was off then started it to finish charging. Any idea what is causing it to take that long to charge?
72gmc4x4
Posts: 42
Joined: Wed May 04, 2016 11:19 pm

Re: Black oil on orifice tube

Postby 72gmc4x4 » Sun Jun 11, 2017 1:02 am

Low and high side pressures were equal while AC on so bad compressor.

How much oil do you add to replace compressor? I believe total oil for a new system is 8oz.

2000 chevy tahoe with dual AC.
Dougflas
Posts: 190
Joined: Mon Apr 18, 2016 6:10 pm

Re: Black oil on orifice tube

Postby Dougflas » Sun Jun 11, 2017 4:09 am

Make sure both hand wheels on the gauges are closed. Pour the oil out of the old compressor and measure it. Put new oil in the new compressor in t he amount that you drained.
72gmc4x4
Posts: 42
Joined: Wed May 04, 2016 11:19 pm

Re: Black oil on orifice tube

Postby 72gmc4x4 » Mon Jun 12, 2017 10:41 pm

Thanks Dougflas you been a lot of help.

I have one more question. Hopefully someone can help me.

It's an early body style 2000 Chevy Tahoe with Dual AC with 5.7L. That year there were two body styles. How much oil and refrigerant does this take? I've been told 8oz or 11oz of oil. And 44oz, 48oz, or now 3.5lbs of refrigerant. Techchoiceparts.com says 48oz of refrigerant and 11oz of oil.

How do I find out without a doubt how much my Tahoe takes?
Dougflas
Posts: 190
Joined: Mon Apr 18, 2016 6:10 pm

Re: Black oil on orifice tube

Postby Dougflas » Tue Jun 13, 2017 4:40 am

Is the a factory under hood label indicating the correct oil and refrigerant charge?
72gmc4x4
Posts: 42
Joined: Wed May 04, 2016 11:19 pm

Re: Black oil on orifice tube

Postby 72gmc4x4 » Tue Jun 13, 2017 10:20 am

The accumulator says 44oz of r134a and the compressor said 8oz of oil.
Dougflas
Posts: 190
Joined: Mon Apr 18, 2016 6:10 pm

Re: Black oil on orifice tube

Postby Dougflas » Tue Jun 13, 2017 1:21 pm

OK, so there is your answer

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