Oil amount determination with different style replacement compressor?

[Christine_208]

Hi all,

New the forum. I hope my question is not too simple but perhaps other newbies will find the discussion useful.

Situation:
1999 Chevrolet Blazer, 4.3L, doing major repair and replacement of parts on AC system.

Parts replaced or to be replaced:

• Condenser,
  Lines to compressor of which one has a built-in muffler,
  Accumulator,
  Orifice tube,
  Compressor*

Parts flushed:

• Evaporator and
  evaporator hose/tube.

* Compressor is a GPD Sanden style (GPD pn 6512124) which is a functional replacement for the original equipment style GM calls an HT6.

Question: With my system now with no oil, how do I determine the total amount of oil to add?

The label on the side of the original compressor states that the oil capacity 8.0 oz with the official GM manual stating that the total amount of oil for the system is also 8.0 oz. The label on the side of the new compressor states that the amount of oil is 6.4 oz. Am I correct to assume that the oil amount identified on the compressor labels is the total amount of oil that should be in the system when using the corresponding compressor? I.e. With the new compressor, the total amount of oil for the whole system should be 6.4 oz and not the 8.0 called for in the manual and that is listed on the original compressor?

I can see how with a different compressor design, less oil could be needed although it seems odd that the specification for the new compressor would be for the same amount of oil irrespective of the particular system. Then again, the original compressor was likely used on many GM vehicles all with only slight differences in their system components/geometry.

Finally, for whatever total amount of oil I should put into the system, should it all go into the compressor? If not, where else should I put some of the oil? My system is not one with a second evaporator so there are no extra components besides the main system.

Thanks

[cool2bcool]

Here is my take, the short version. Make sure system is clean, and use the full 8oz original amount.

Here is the long version.

1) who is to say what system the new compressor goes on, some systems may have different size heat exchangers, lines, total refrigerant volume ext. So right off the bat I wouldn't listen to what the replacement says on it, since chances are that same compressor is used for several different systems-as you already noted.

In the couple of dealings I've had with GPD I did not like the products. I had ordered a GPD drier, and a GPD all inclusive o ring kit for the truck. The drier did not come with o rings, and the all inclusive kit also did not have the right size o rings to fit the drier! In addition to that, there was aluminum chips and flashing when I looked inside the drier, almost like GPD tapped the holes AFTER they welded it up and put the desiccant in it. So for that reason I pretty much wrote them off/dont trust what they say.

2) your system was designed around the fact that there would be 8oz of oil hindering heat transfer. So its not like you would be adding more than original and losing some efficiency, it would stay the same.

3) Your compressor would be "happier" with more oil than less, so you are good to go there. IMO no reason to go with the lesser amount.

Now as to where to put it, i would put some in low side of the compressor and turn the hub around several times once installed as to make sure it will not "hydro lock". THen the remaining balance you could put anywhere since the system will start circulating the new oil throughout the system. However if it was me, I would put it in the accumulator. Its not only easy to do and for sure will hold all of the remaining oil, the compressor is the next thing down the line to see that oil-which is the only component that needs it in the system.

[Christine_208]

UPDATE:

I got a reply from GPD. I had to use their FB messenger to get their attention but here is what I learned.

They confirmed that although originally my system called for 8.0 oz of oil, because the replacement compressor is a different style, a Sanden vs. the original HT6, then the correct amount of oil for the whole system is 6.4 oz, the amount listed on the side of the new compressor.

I sure hope they make their directions more explicit so that others like me don't have to go through this.

Thanks!

[ice-n-tropics]

If it was genuine Sanden the correct oil amount in already included inside the new Sanden replacement compressor which has generally been 8 oz for a CCOT system.
hotrodac