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  #16  
Old 07-10-2018, 07:20 PM
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It is normal for the compressor to get hot after running. It is doing a lot of work pumping the refrigerant, it has to get hot. I wouldn't replace the ETS before testing it first. It's a robust part and don't go bad often. When you evacuated the system, did you have both high and low side ports connected to the manifold and evacuated with both ports open? If you only evacuated from the low (suction) side, the system was not fully evacuated.
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  #17  
Old 07-10-2018, 07:24 PM
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80% is the starting point for a 134a conversion. My SDL wound up around 87% to be charged correctly, but it's a different system with a very different condenser. I run ester oil in mine as well, it started out as R12 but had an expansion valve failure and when I went to gas it back up, the valve on the tank failed and sprayed everywhere but out the hose! (I was pretty pissed).

The compressor will make a bit of a grumble when it runs, any reciprocating compressor will. It shouldn't be a loud growling like failing bearings though. A moan is acceptable, growling or howling is not. The compressor body can be engine temperature or higher depending on load and ambient temperature. Remember, the "head" of the compressor will be the same temperature of the liquid line before it goes into the condenser. It will be HOT. The compressor is cooled internally by the refrigerant.

Before adding oil to the system, was the rest of the system flushed? Does the FSM call for 8 oz of oil in your system? If you have too much oil in there, it will act just like a restriction. If there's enough oil in there, you can have the compressor trying to compress liquid.
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  #18  
Old 07-10-2018, 07:36 PM
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Post R143a Conversions

"80% is the starting point for a 134a conversion."

Good stuff to know ~ most 'mechanics' I talk to and everyone here on this forum, always insist you need _MORE_ R134a, my books says _less_ .

Is there a basic low side pressure one should look for with R134a ? .
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1982 240D creampuff 370,000 miles
1978 300CD back from the dead&1980 300CD ~ SOLD
1984 300CD KEEPER ! 430,XXX miles
1984 Euro 300TD Fully optioned SWMBO's
1974 350SLC 4 speed stickshift SOLD & missed
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  #19  
Old 07-10-2018, 08:38 PM
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R134a is a lighter molecule than R12, thus for a given volume of gas the weight is less. 80% of the R12 weight is a good starting point in most systems, however it can still be a little undercharged. That's where checking pressure becomes important.

Pressure should always be checked both high and low side. Comparing the two tells you what's going on with the system.

For a 90˚ ambient temp, the high side will be somewhere 200-250PSI and low side will be somewhere 35-45PSI depending on the load on the system. High head and high suction pressures indicates overcharging. High head and low suction indicates a restriction. Low head and high suction indicates a weak compressor. Low head and low suction indicates undercharging. Looking at only suction pressure presents an issue where you attempt to charge based on pressure, but can easily overcharge the entire system. Gauge pressure will vary based on the ambient temperature and the load on the system. Always check pressure with all windows open and fan on maximum speed.

It goes without saying, but never charge by pressure alone. Always weigh in the charge then check operation and tweak the charge if necessary.
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  #20  
Old 07-10-2018, 08:46 PM
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I just read on a few threads here an elsewhere about 8 oz total. I might be a tad less actually.

I did vac with manifold on both high and low sides together. Only thing Iíd say is possibly that my manifold doesnít have a purge valve - so itís possible that the air that was in the length of the yellow hose from can to gauge is contaminating it all.
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  #21  
Old 07-10-2018, 09:11 PM
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Yellow hose w/o a purge valve can be purged by running refrigerant through it before connecting it.
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  #22  
Old 07-11-2018, 12:22 AM
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Thanx D3 ~ I'm sure I over charged my 300TD, it never did blow very cold and blew a hose in Indio, Ca. when I pulled up to a stop light .

@ idle the low side went way above 45 PSI .

I think I'll leave the AC repairs to the pros from now on .
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1982 240D creampuff 370,000 miles
1978 300CD back from the dead&1980 300CD ~ SOLD
1984 300CD KEEPER ! 430,XXX miles
1984 Euro 300TD Fully optioned SWMBO's
1974 350SLC 4 speed stickshift SOLD & missed
Krazy Kommie Ural Motos (3)
BMW Moto R60/6 Barn Find, 8,000miles
1959 VW #113 Deuxe Beetle, 36hp engine, stock
Junk, Rust, Arthritis, Crushed Spine,Broken Neck&Back
Memories &Peace Of Mind
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