On my 84 300SD, my low side reads 40 psi. Shouldn't the metal line feel like 40 degrees? I have 68 degree discharge air with 90 degree ambient air. Could I have too much oil in the lines?

When I originally bought the car, the oil would bubble out of the schaeder valve whenever I removed the gauges. I knew then there was too much oil in the system. I flushed the system with an air gun and got quite a bit of oil out of the condenser, evaporator, and compressor. I put 4 oz in the compressor, 2 oz in the evaporator and 2 oz in the condensor.

Could there still too much oil? How is the best way to get all of the oil of the system and start from scratch with new oil?

That sounds like a mess...
You flush the whole system and put back in the proper amount.
It is very bad to have too much oil in the system.
You do NOT flush 1. the compressor (you just empty it manually)
2. the expansion valve
3. the evaporator ( although some books say you do )
4. to do the condensor properly you may have to take it out of the vehicle and be able to rotate it.
5 . the Reciever/dryer ( you put in a new one )

The bearings on my compressor were fine. But, there was so much oil in the system when I bought the car that compressor clutch squeked at idle speed. It also was at least a 30 hp drag on the engine.

With the flushing I did, I can barely feel the compressor drag the engine. The compressor is quiet and the clutch does not slip. Now the system runs mineral oil and Duracool instead of 134a and PAG oil (I assume).

I have a new H-block. Those are difficult to put in.

It is bad to have too much oil. Oil won't cool like refrigerant.

If the low side is 40 psi, shouldn't the pipe feel like 40 degrees not like 68, and is that sign of too much oil?

VWbuge, I can tell what you are about to ask so I will go ahead and answer you ....

If you will do a search,,, I know that a chart has been posted, maybe generic.. and maybe some have put up the amounts for your specific machine....

Well,,, ok ,,, let me try to cover what you may have been meaning also...

Are you thinking that the bearing went out because you had too little oil in the system ? In that case you flush and start over measureing and adding oil to each part as specified...

If you do not suspect that... then what the books say is to carefully measure the amount in each of those two items... and put in exactly that amount of fresh clean newly opened oil back into the new ones ....

However, I do not think the Delco 4 cylinder has a resevoir for oil like the others....it just works on what is transported through it by the refrigerant ( which carries the oil with it )...

My system was previously converted to R134a. Since then a bearing seems to be moaning in the compressor. I just bought a new comp and drier. When I install these items how much oil do I need to dump in the comp and then in-line?

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

I have never read of any way to check to see if you have too much oil... it is either flush and measure the correct amount into it... or replace what is lost when replacing a particular part... other than that there is no way to tell.. unless you lock up the compressor or something like that...

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In the case of replacing compressor and drier it is important to know WHY you're replacing the compressor. If it is just a shaft seal leaking, then you can get by with replacing it and adding a few ounces, but I personally would not do that. I would flush the entire system and put in the correct amount of oil. I say this without knowing the system. If everything else had been working well and it had never been recharged then just adding whatever volume you could get out of the original compressor would probably be okay.

In the case of replacing for a leaky shaft seal on a system with a history of leaks and problems, you should flush and put in the specified volume of oil.

In the case of replacing a compressor that has had internal failure the ENTIRE SYSTEM MUST BE THOROUGHLY FLUSHED! You should flush, flush, and flush again. If you don't ENSURE that all debris from the failed compressor is totally removed, then the act of replacing the first compressor will only be practice for doing it the second time.

This means breaking all connections and flushing thoroughly in both directions. Sometimes the serpentine condensors cannot be flushed enough and must be replaced.

Did I mention that you should thoroughly flush the entire system in the event of internal compressor failure?

Good luck,

Larry,

I notice they sell a $2,000 machine to flush the system.

Is it possible for the shade tree mechanic to throughly flush the system with just an air compressor and air gun?

A good air compressor and some flush (or brake cleaner) should do the trick.

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Matt
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1995 E300 Diesel (Die Blau Frau)

Many places like Carlisle Auto Air sell flush guns ( about $45) to be used with your air compressor ... they also sell recovery kits so you can reuse it.... the pro models run it through multiple times and filter as it goes through the system... you can do that shade tree and do a great job , just takes a little care and time...
I would split my flush into Gross and clean.... use the Gross first on all parts.. then use the clean.... and preferably new clean on each section being flushed the last time....

Is there any way to get some oil out without flushing the system if you've added too much?

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83 240D four bagger stick diesel 276K

If you mean without evacuating the system ... No.
If you take out the refrigerant then you could ( if you actually know HOW MUCH over filled you are ) remove the reciever/dryer for instance, and put a new one in without adding any oil to it.. as you would normally do.. that would decrease the amount in the system by the amount in the removed Reciever/Dryer....

This may be the exact problem with my A/C. Larry helped me recharge the system after I converted it back to R-12, but the (new) compressor did not make enough pressure to cool adequately. Is it possible that I have too much mineral oil in the system? Would the symptoms be similar?

As I was attaching the new compressor, some oil spilled out of the unit, but I was unsure of the amount. When I had it all back together, I added an amount of oil that I THOUGHT approximated the lost amount. I may have gotten WAY too much back in, thus exceeding the 8 oz. recommended. If so, would the result be as I described above, i.e., low high-side pressure?

Side note: The last thing I did to the system before charging was to remove the R-134 fittings and insert valve cores. When I did this on the high side (the fitting is at a low point), some oil came rushing out. Would this be normal?

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Matt
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1995 E300 Diesel (Die Blau Frau)

Wow...that describes a completely different method for adding refrigerant oil. I simply poured it into the two holes on the back of the compressor before attaching it...and a goodly amount came flowing back out once I had it level and ready to bolt up. Mind you, I did turn the compressor a few times while on the bench to distribute the oil.

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Matt
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1995 E300 Diesel (Die Blau Frau)

That is one way... but you can just put the right amount into the compressor and each of the items you have off after you have flushed.... and when replacing just one item... like the R/D then you measure the amount which was in the old one.. and put brand new, newly opened , correct type oil into the new one, which is kept closed until the very last second...

PS, one of the things engineers like about the Delco 4 is that it can be run in any position..... It can do this because it HAS NO Chamber for holding oil.. it is lubed only by the oil flowing with the refrigerant....
The Yorks can only be run in two positions...
I do not know about the other rotaries.. but suspect they must be horizontal...