98 Buick Park Ave AC troubles - Hi side won't build

[DSK777]

John,

Thanks very much for this info. Next recharge attempt forthcoming...
I started reading about the VD compressors on the MACS website. It was enlightening, realizing that even when the clutch is turning it is operating at a smaller capacity and increases accordingly.

The old OT tube was not bad, just darker in color and a few specks on the screen but not severely restricting flow, it looked to me.

The original Delphi upon disassembly for the seal kit, showed some fine, light brass colored glitter throughout, not heavy but a decent sprinkling.

I hate to mistreat a new compressor...I had hoped the flushing would improve things to a satisfactory degree. Learning a lot...

[JohnHere]

Thanks very much for this info. Next recharge attempt forthcoming...
I started reading about the VD compressors on the MACS website. It was enlightening, realizing that even when the clutch is turning it is operating at a smaller capacity and increases accordingly.

Right. Even though the clutch is engaged, a manual control valve uses pressure to vary compressor displacement, while ECM/PCM commands based on sensor and control-head input regulate the electronic version of the valve. Both types vary a compressor's displacement in a similar manner: By changing the angle of the swash plate, and hence, piston stroke.

The old OT tube was not bad, just darker in color and a few specks on the screen but not severely restricting flow, it looked to me.
The original Delphi upon disassembly for the seal kit, showed some fine, light brass colored glitter throughout, not heavy but a decent sprinkling.
I hate to mistreat a new compressor...I had hoped the flushing would improve things to a satisfactory degree. Learning a lot...

I'm sure flushing the components you mentioned earlier helped to remove a lot of the metallic glitter, but it's always best to replace the condenser along with the compressor and flush the rest. The Accumulator or Receiver/Dryer, depending on which one a vehicle has, can't be flushed and should also be replaced last—and each time the system is opened to the atmosphere. In this repair, if the car owner needs to economize on parts replacement, we could take a chance on re-using the original condenser (guessing, a new one would cost less than $150) since the original compressor doesn't sound like it was internally disintegrating.

As far as re-using the various seals, you're taking a chance that the system will leak in the future. The oil you noticed might or might not be residue left from the oil you applied earlier. If you want to ensure a leak-free seal at every joint (and who doesn't?), purchase a small bottle of Nylog Blue and apply some (a little goes a long way) to every o-ring, seal, and threaded connection instead of plain PAG oil. I've never heard of a connection leaking after using it.

[DSK777]

John,

Bringing an end to this thread... The problem is solved. I didn't understand the VD compressor concept previously, and upon following your recommendations, everything seems to be working upon my most recent recharge. I also did not realize the length of time this process takes. In all, it probably was about 20 min.
But with an ambient temp of 81F, running the engine at around 1500-1800 RPM, pre-warming the cans and recording their weights throughout the process, at last the air is cold. The final pressures whilst running AC with a full charge of 32 oz 134a were L: 29 psi, H: 145 psi.

I'm sure I'll be back for more education later. I appreciate the help and patience very much.

Eric

[JohnHere]

Bringing an end to this thread... The problem is solved. I didn't understand the VD compressor concept previously, and upon following your recommendations, everything seems to be working upon my most recent recharge. I also did not realize the length of time this process takes. In all, it probably was about 20 min.

Glad everything worked out. I think I forgot to mention earlier the length of time the refrigerant recharging process should take, presuming no problems crop up. I meant to say about 20 to 30 minutes, so you are right on target.

But with an ambient temp of 81F, running the engine at around 1500-1800 RPM, pre-warming the cans and recording their weights throughout the process, at last the air is cold. The final pressures whilst running AC with a full charge of 32 oz 134a were L: 29 psi, H: 145 psi.

The low-side pressure is fine, but the high side is a bit low. Are you sure you recorded that one accurately? On more than one occasion, I've scribbled-down data that I couldn't read later

I'm sure I'll be back for more education later.

Post anytime should you need additional help.

[DSK777]

True regarding the scribbling of data...I actually remembered to take pictures during the charging, with a final picture of the MGS post charge. Unfortunately it says the file is too big, but the readings I did verify.
I am using the new Denso comp instead of the OE Delphi but
I am guessing whether there may be excessive PAG oil in the system, after I erroneously added all 9 oz to the previous compressor and attempted a charge. I do not know what effect that may have, if any.
Another note, the Denso contains PAG 46, while the Delphis ran 150.

[JohnHere]

I think you inadvertently over-filled the system with oil if the Denso compressor and the junkyard compressor came with all 9 ounces in them. It's very difficult to correct that now, though, because everything you do would be guesswork. How much oil do you remove? Who knows?

I responded to another question about that under a different topic. Better to be over-oiled than under-oiled, though (within reason).

PAG-150 is a higher viscosity oil than PAG-46, but I don't think you'll hurt anything by mixing the two oils.

If the system is cooling well, the pressures are good (chalk up the lower HS pressure to effective condensing), and the compressor is relatively quiet, I would tend to leave it alone.

[DSK777]

Good info to know. I shall heed your recommendations.
And as always, very grateful for your assistance. I'm glad to have happened upon this forum.