Sanden 4440 install

[L31MaxExpress]

Yes I added 5oz to the accumulator and so I was accounting for 9oz of fresh oil plus 2oz of oil left in the rear ac lines and rear evaporator to bring it to a total of around 11oz. But now I have 15oz in there and my gauge pressures are at 70/250 in 90 degree ambient temperature.

Can all of the extra oil be the reason why I can't get the low pressure side anywhere near 40psi?

Extra oil is not good. It blocks heat transfer to some extent and compressors do not like compressing liquid. That being said pressures should not be that far off with a few ounces too much oil.

To purge excess oil, I would consider doing the Sanden oil test. Run the compressor at the specified RPM. Recover the refrigerant. Remove the compressor. Drain the compressor of oil into a clean measured container. Measure the correct volume of oil accounting for the residual oil in the compressor specified in the Sanden manual. Then add back the specified amount for the RPM it was run at. Mine has right at 11 oz in it.

 

[L31MaxExpress]

My low side pressure in 90°F and +70% humidity was 35ish at idle after 10 minutes and dropped under 30 psi after a few minutes at 1,150 rpm. It was cooling about ~46°F then dropped to ~38°F. High side pressures 220-230ish. Granted I am not running R134a which would probably run 5-8°F warmer air at the same pressures.

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[1998_K1500_Sub]

To purge excess oil, I would consider doing the Sanden oil test. Run the compressor at the specified RPM. Recover the refrigerant. Remove the compressor. Drain the compressor of oil into a clean measured container. Measure the correct volume of oil accounting for the residual oil in the compressor specified in the Sanden manual. Then add back the specified amount for the RPM it was run at. Mine has right at 11 oz in it.

The "is there a proper amount of oil in the system" test @L31MaxExpress mentions is described in this snippet from the "Sanden SD Compressor Service Guide v2".

@L31MaxExpress ran the above test on his dual-AC system equipped with a Sanden #4261. Coincidentally GM originally spec'd his system as requiring 11oz of oil, so the test was an interesting step toward validation of the GM "11oz" spec's suitability with the Sanden retrofit. See his comments about the test results, here:
https://www.gmt400.com/threads/sanden-4440-install.58192/post-1248723

The complete "Sanden SD Compressor Service Guide v2" is available on-line from Sanden.

 

[L31MaxExpress]

The "is there a proper amount of oil in the system" test @L31MaxExpress mentions is described in this snippet from the "Sanden SD Compressor Service Guide v2".

@L31MaxExpress ran the above test on his dual-AC system equipped with a Sanden #4261. Coincidentally GM originally spec'd his system as requiring 11oz of oil, so the test was an interesting step toward validation of the GM "11oz" spec's suitability with the Sanden retrofit. See his comments about the test results, here:
https://www.gmt400.com/threads/sanden-4440-install.58192/post-1248723

The complete "Sanden SD Compressor Service Guide v2" is available on-line from Sanden.

11oz spec was actually not GMs spec for my system as half of my system is not GM. But the test did verify that Advanced Air was close for the Sanden/Parallel Flow/R152a. R152a seems to carry oil equivelant to R134a despite having ~55-60% charge by weight.

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[hekg]

I finally finished replacing practically everything in my hvac system except the two evaporators but I got it to cool in both the front and rear airs.
My question now is the total refrigerant required. I have read that my Tahoe requires 64oz but since I now installed a parallel tube condenser then I would need to use less.

I added four 12oz cans but the pressures seemed to high so I stopped there. The low side was at 50 and the high side close to 300.

Is it safe to continue to add refrigerant? Maybe one more can to take it to 60oz?

 

[1998_K1500_Sub]

My question now is the total refrigerant required. I added four 12oz cans but the pressures seemed to high so I stopped there. The low side was at 50 and the high side close to 300.

Is it safe to continue to add refrigerant? Maybe one more can to take it to 60oz?

You might follow @L31MaxExpress' method described here, regarding adding refrigerant until the temps at the evaporator outlet and a bit further downstream are within a desired range:

https://www.gmt400.com/threads/sanden-4440-install.58192/post-1249363

@L31MaxExpress isn't alone in his perspective, I've read similar methods elsewhere.

Hopefully he'll notice my reference to him here, and comment on your pressures.

You might wish to add some detail about your high-side pressure, e.g., test conditions (engine RPM, airflow across condenser, ambient temp) and AC settings (blower speed, recirc on/off, windows open / closed, etc.)

 

[L31MaxExpress]

You might follow @L31MaxExpress' method described here, regarding adding refrigerant until the temps at the evaporator outlet and a bit further downstream are within a desired range:

https://www.gmt400.com/threads/sanden-4440-install.58192/post-1249363

@L31MaxExpress isn't alone in his perspective, I've read similar methods elsewhere.

Hopefully he'll notice my reference to him here, and comment on your pressures.

You might wish to add some detail about your high-side pressure, e.g., test conditions (engine RPM, airflow across condenser, ambient temp) and AC settings (blower speed, recirc on/off, windows open / closed, etc.)

My perspective, high pressure would mean poor airflow or high ambient temps. Definately need more details on the testing. As for the parallel flow condenser, the differences is likely a few ounces not close to a full 1 lb.

 

[udidwht]

Some systems have not predetermined specific amount. It's determined by pressure of low & high readings within a certain range.

 

[L31MaxExpress]

Some systems have not predetermined specific amount. It's determined by pressure of low & high readings within a certain range.

That and Superheat/Subcooling measurements.

 

[L31MaxExpress]

Vanula escaped from the laboratory today for a while. I drove it around for close to 1 hr. The newly built and replaced steering box and front sway bar end links made it drive like a dream. It was sunny and 97°F. A/C was blowing the the 30s as long as I was moving. After 10-15 minutes I had already knocked the blowers down to medium low up front and turned the rear off. After 20 minutes I had to knock the recirculate off as the air was so cold it was freezing my knuckles on the steering wheel. I eventually set it to Bi-Level even and it was still an icehouse inside the van.

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