RickD

I bet you have a bunch more heater repairs than I do... One thing I left out. My machine has a line flushing feature for use with hybrids. It burns 1.5 lbs of filter life (limited by Robinair to 150 lbs before filter change). I do use this feature when I hit a bad one AFTER I'm done with the job. I clear the lines immediately after I'm finished... One thing that's cool is when I get a a massively over oiled one and the trap has 8 oz of oil in it the oil bubbles like a coke for 2-3 hours and the 8oz drops to 6oz The oil has liquid refrigerant in it. This phenomenon is useful when you have to open a system. It will "out gas" for a couple of hours AFTER recovery. If you tightly plug the lines it will "pop" when you pull the plugs days later, sometimes it will blow the plugs off (bad). Often I will use a balloon on one side to allow for expansion. If your system is outgassing when you plug it and the plugs stay in the dryer does not get poisoned with ambient humidity and I will commonly re-use the dryer. If I can I leave the systems in vacuum overnight (machine hooked up but turned off) and re-pull in the AM. This vastly reduces the moisture in the system.

I use a Yellow Jacket "trap" (38080) on every car I recover. I'm running a Robinair 34788 NI-H and have not had any trouble in 5 years. I recover from low side ONLY (less oil come out) and the trap has not missed a drop. The machine never recovers oil. I intentionally recover my own cars without the trap to test the machine once a year. Oil recovery works fine then. The machine needs a tiny amount of oil to keep the solenoid seals lubricated. I believe 90% of the vehicles I service have sealant in them. The little test kits are not worth the trouble IMO. I do not use them. They are not accurate enough for me and take too long to test. It is difficult to find straight refrigerant in the DIY auto stores. Almost everything has oil and sealant... I have NEVER seen the sealant fix a leak but I have seen the sealant take systems out. The usual culprit is a membrane that the American manufactures like to use as a debris screen. The tiny holes in the membrane get clogged with the sealant and you find ALL of the oil in the system on the feed side of this membrane. GM SUVs with rear AC are the worst culprits. The tiny screen is inside the liquid line at the bulkhead fitting in the rear. Most techs don't know it's there as it is not a normally changed part (and it should be). A Murray part # for the little screen is 39335. It looks like a 1/4 scale orifice tube screen. The liquid line front to back has enough volume for the entire oil charge. If you have a plugged one and you don't change it you will have a comeback within a year. Rear AC will be wimpy as well. GM condensers with a replaceable dryer cartridge (Cadillac SRX) also have a super tiny membrane inside the dryer that will clog. Symptoms are low pressures on both sides, piss poor cooling, and a viciously hot discharge line. There is a TSB regarding this. If you refuse to service your customers cars because they might have sealant you are destroying your relationship with those customers. We have to service the systems and educate the customer. Occasionally I hit a system that has been massively over oiled. The sealant is everywhere. I will commonly replace compressor, condenser, orifice/TXV, dryer/accumulator, and discharge line. I will over flush remaining lines and evaporator and offer NO warranty. I haven't had a comeback on ANY of those but I believe I have been lucky. Customers will seldom pay to have the entire system replaced and see the shop as an "over charger". They will not come back to you for the other things they need. My Robinair machine's manual states "any leak sealers found inside the machine voids all warranties"... I run a shop in Texas that specializes in AC repairs.