ALL the oil sending units are plastic. Don't hold that against GM. How many years did you have on it before it failed? They usually go that way regardless of how they are made. Not that GM's compressor is bad, I just know of Sanden's reputation and have one myself. My wife used to have a Durango and that had a factory Sanden that never failed. Unfortunately the evaporator coil did. Ugh what a job that was.
Here is the tools for your job
flush spray can
manifold gauge set
vacuum pump
Not all stores have these available so call first to ask. They can usually transfer the tools they don't have to their store on a temporary basis from the stores that do, if the other stores aren't close to your location.
Most often when a compressor fails (in my case it didn't fail but still put filings in the orifice tube) it will put metal filings into the system. This is why you have to replace the orifice tube and flush the system. Look closely at your orifice tube when you remove it. It will have metal filings in it. I can just about guarantee it.
Also I never do my own charging. I've done the complete job except for vacuuming and charging. By that I mean, I flushed EVERYTHING, replaced all components and hooked the system back up. Then took the truck to a shop to have them vacuum and charge it. However if you got to that point on your own, the rest is not that hard.
So you could buy and replace the necessary components. Flush out the ones that need to be flushed so you know the job was done correctly. You would only need the flush spray can and flush fluid listed above (as long as you have a compressor).
The
most important point is that the vacuum holds for hours before you charge it.
Finally here is one of many links to a sanden BOLT IN replacement unit like I got. The Sanden part number is 4440.
sanden compressor
Another thing I just remembered. The hoses that connect to the compressor have a schrader valve that often (I mean a lot) sticks. It would be a good time to replace that set of hoses. If you fill the system and that valve sticks, you cold loose a lot of refrigerant.
All the components you need are available at O'Reillys. The hose set, the accumulator, the O-rings and washers, R134 and more.
Incidentally I wanted you to see the micron gauge I was speaking about with regard to vacuum.
micron gauge
As I mentioned before, if you achieve 500 microns or lower while doing the vacuum, there is no question you DO NOT have a leak in the system.
Write us back and let us know how you made out please.