I recently purchased a 97 Blazer with a 4.3 L engine. The compressor clutch kicked on and off repeatedly. Indicating low refrigerant. I had the system evacuated and recharged, with dye added to check for leaks. AC blew ice cold for about 24 hours. The next morning I opened the hood to find dye coating the compressor casing. The truck sat for several months before I bought it. So I'm assuming the seals are dry-rotted. I plan to replace the compressor, dryer, and oriface tube. Then take it to be vacuum tested and charged. I have two questions. First where is the oriface tube located? Second, how much oil should be added to the compressor, and where do I add it? Thanks in advance.
That was actually 3 questions.

 

well, the orifice tube is in the low pressure fitting of the condenser. you should probably get a new condenser from advanced auto, it comes with a new orifice tube in it. I didn't replace mine, after it sat quite awhile not working, I flushed it out good, but crap in my old condenser clogged up my new orifice tube after about a month. your PAG150 oil comes in a 8 oz bottle. you pour half in the low pressure side out your new accumulator, the other half goes in the low pressure side of your new compressor. let your compressor sit pulley side down for a few minutes so the oil lubes your front seal good. after installing your new compressor, rotate the pulley by hand for 15 -20 revolutions.

 

The fixed orifice tube is inside the inlet tube of the evaporator. The high side liquid line fitting, directly under the accumulator, must be taken apart to replace the orifice tube. As for oil, system capacity is 8 ounces of PAG150. The entire system must be flushed to remove all old oil, (& debris) before adding the new oil. The oil must be evenly distributed between the compressor, condenser, evaporator, and accumulator. If the system is overcharged with oil, it will not cool correctly. If the system is undercharged with oil, it will not cool correctly AND the compressor will fail prematurely.