CRBWS6

iTrader: (1)

Would the moisture usually be removed if I can get them to re-do the evac and refill of the system?

RockinWs6

The desiccant bag in the accumulator should eventually soak it up. I've experienced the same problem you have with these cars. It could compressor not loading up properly too. If you have similar system you can compare it to on a warm day you may find your answer. I'd compare the pressures and the temps. You could pull the system open at the orifice tube and carefully inspect it for dirt or moisture.

Another good test is the temp of the evap inlet and outlet and return line back to the compressor. If its ice cold and the air inside is warmer than it should be you have some kind of hot air leakage inside the car. Remember the heater core in these cars is always full of hot coolant.

I've noticed on my low mileage WS6 the evap inlet and outlet are cold BUT not quite as cold as they should be. I'm betting on a compressor problem, I don't think its loading up fully. I've run in to this a few times on these newer systems.

CRBWS6

iTrader: (1)

Thanks for a very good troubleshooting list

So if actually is just a little moisture in system, it would go away over time and the cooling could improve?

The compressor is a brand new OEM unit (not reman), so I would hope it is "loading up" properly. Dumb question - what does "loading up" mean?

Good idea to check a similar system. Maybe I could take my car and LS1 truck to the dealer for side pressure check. The truck vent temps under exactly similar conditions are noticeably colder (7 deg).

Vent temps were perfect the day before and it's unlikely that a air mix issue would crop up as a result of compressor replacement.

I am beginning to wonder if the dealer machine might have a calibration or weight measurement issue?

RockinWs6

Could be its not charged properly.

The compressors are variable load type, look up GM f body variable displacement compressor. Lots of info that can explain it better than I.

CRBWS6

iTrader: (1)

Agree - improper charge (high or low) is the most likely culprit, but your suggestion to read about variable compressors gave me some hope (maybe false hope) that the compressor is intentionally not 'loading up" (i.e. piston de-stroked). This is because the ambient air (and cabin air) is cool right now by AZ standards (under 80deg & 15% RH).

From what I have read, the compressor on Silverado's might actually be fixed (i.e. not variable), so this would be bad vehicle to compare pressures with.

That said, the last word I had with the dealer was to table it and check the performance again in the summer. They said they will stand behind their work. If it blows the same 45deg vent temps in the AZ heat, it will be fine.

For now, I am just glad to not be leaking PAG everywhere and to have a quiet compressor clutch

CRBWS6

iTrader: (1)

Now that it's summer, I thought I would provide an AC performance update. The Korean made AC Delco compressor is still pumping. Although it's very acceptable, it's not as cold as factory. The slight chirping sound noticed since replacement is still present, but not a big deal. If you've heard an FRS at idle, it's a similar sound.

The duct temp (Outside Air, Fan at 2) blows about 5 deg warmer than before (45-47 deg) on HOT Arizona days which is very comparable to Nissans and Subarus I have recently tested.

For comparison, my Silverado still blows 40 deg. This may not sound like much, but 5 deg is VERY noticeable when it's this hot out.

fleetmgr

It could be moisture in the system, although if it's been evacuated properly this is unlikely. Moisture will create a little ice ball in the expansion valve, blocking refrigerant flow. Normally, it blocks it completely, not partially. Indications would be cold air at first, turning to ambient. Stop the car for a while, and it does the same thing all over again.

If the compressor has the capability to unload (not pump refrigerant) based on load, this would be my first suspect. At any rate, if the dealer did it, it's their problem to get it into spec. It's your problem to make them.

RevGTO

iTrader: (12)

I had the compressor replaced on my son's Firebird a couple of years ago and it's never seemed to blow as cold as it did before, or the original units on my Formulas.

RockinWs6

I had cooling trouble after the car sat for a few years. Compressor wasn't loading up completely so while the air was cold coming out the ducts it just wasn't ice cold like it should be. I fooled around with the charge and looked at the pressures but really couldn't find anything wrong other than just not as cold as it should be. I also noticed when the compressor would load up completely it got a little noisier and then it would get ice cold.

Now I've been doing ac work on cars buildings etc for a very long time and I honestly couldn't see the difference in the pressures like I thought I should. I have to assume its more about not enough coolant flowing through the system than it is pressures.

I really don't know these variable compressors well enough to tell you how to properly test it under full load.

I can you this much if the evaporator isn't completely saturated with coolant you wont get the ice cold output you are looking for. A good test is to compare pressures to temps at the evap inlet and outlet. This can tell you if there is moisture in the system and if the evap is completely filled. The return out of the evap at the accumulator should be so cold the moisture on it is frozen. If not there is not enough coolant in the evap and that could be from many different reasons. Low charge, moisture blocking the orifice tube, compressor not loading properly, and over charging will cause problems too. Also be sure the condenser is clear of any debris, paper etc.

To get ice cold air out the ducts the coolant in the evap must be cold and fully saturated so it transfers the heat from the air moving across it completely. If you have the proper temp measuring equipment you can measure the actual temp rise across the evap. As the coolant enters it expands quickly and gets extremely cold but as it moves through the evap it picks up the heat from the air moving across the evap. So the air passage entering the evap needs to be clear too.

Like I mentioned before there is much better info than I can pull out of my head online. Search far enough and you will find your answer.

Firebrian

Most of the dealers that sell a compressor under warranty require a new orifice tube and drier/accumulator/LP line assembly. At $45-$55 for the pair that's cheap insurance imo. And you can find cheaper models than that.

The AC system went on my '99 two years ago and it ended up being the compressor seal. Had a new Delphi unit installed along with a drier/LP line and a new orifice tube. AC system repairs tend to be expensive so I couldn't see re-installing a 13 year old drier/desiccant and risk going back in there again. That LP line also has 4 crimped fittings on a pair of rubber hoses. Old rubber doesn't fare well in engine compartments.

After all that work was done it leaked a very short time later. Somehow, the HP refrigerant line got "shaved" right across from the HP cut out switch. It must have taken years of contact to wear that metal line down that far. And no one saw it the first time around. Didn't see anything that should have caused that type of external erosion/wear. Ended up replacing the HP line and HP c/o switch as well ($110). Blowing nice and cold ever since.