Automotive Air Conditioning Information Forum (Archives)

JHZR2 on Wed April 15, 2015 2:27 AM

Year: 1998
Make: Chevrolet
Model: S-10
Engine Size: 4.3
Refrigerant Type: R134a

Im looking to replace the leaky HT6 compressor on my 98 Chevy S-10. AC still works but its a leaky mess.

So I plan to go with the Sanden 4440, not the existing delphi type that gets leaky) or the other similar copies.

But there are like ten different variants of this compressor... The compressors, depending upon manufacturer, spec between PAG 48 and PAG 150 oils for the compressor. I dont know what GM installed as OEM.

How much does it really matter? I dont want to cause damage or harm, but the fact that the specs are all over the place for the same unit tell me it doesnt really matter much...

Recommendations? Say the compressor comes with 48 PAG in it. And Im just replacing the compressor, nothing else, and not flushing the system. If the system originally had PAG 150, for example, the viscosity will be way off. So what is appropriate?

Thanks!

HECAT on Wed April 15, 2015 7:43 AM

Just like engine oil, it does not really matter; all engines can use the cheap bulk oil or just mix it up (TIC). But if you want the engine to last, it is best to use the proper OE spec oil. The varying specs are for the many different OE systems that the same compressor can be used. Each OE (compressor & vehicle) has done extensive testing to determine the correct viscosity for their application.

Just replacing the compressor, is called "oil balancing" (a calculated WAG). This requires a clean virgin system and only the OE spec oil should be used. Once you drain and measure how much oil comes out of the old compressor, and you figure out how much has leaked out (the mess); you can then calculate how much oil is left in the system. Drain the "shipping" oil from the new compressor and add back the amount of OE spec lube required. Kind of like putting the oil pan with old oil back on the new long block you just installed; that will work.

So, I am not so comfortable with this process especially with older vehicles, and my appropriate recommendation would be to flush it clean and dry, so you can add the full amount of fresh oil. Use the amount specified for your vehicle and the type recommended by the compressor manufacturer; especially if you are changing to a different compressor.

HTH

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JHZR2 on Wed April 15, 2015 9:46 AM

OK thank you. Ill plan to replace the accumulator and do a flush then. The system works great, the only issue is the seal on the body of the compressor itself, since it I guess is prone to leaking (and why Im interested in the Sanden).

Perhaps a dumb question but I assume that flush solvents will damage o-rings, is that accurate? Solvents and rubber often dont mix, and it may mean more connections to break and replace. Just want an opinion for planning...

Thanks again!

HECAT on Wed April 15, 2015 1:29 PM

For flushing planning, you may want to read the tech paper in my signature.

Yes, some solvents will damage the o-rings, or may even be caustic to the metal parts; others will do no harm to the elastomers (o-rings, seals, hoses, etc.). So knowing what chemical you are going to use (and why), what it will do to the parts of the system, the flammability, the toxicity, and more; will all need to be part of your planning. Tooling & methods to deliver and remove the solvent is going to be key also.

Once the compressor, filter, and orifice are removed for flushing; it usually does not require breaking open more connections for isolation flushing of the Evap loop and the Condenser loop.

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JHZR2 on Wed April 15, 2015 6:50 PM

Thanks again!