Oil when vacuuming ac lines??

[88911coupe]

I have been working on ac system and have replaced nearly all parts including hoses, compressor, and evaporator. I thoroughly drained the oil from the new compressor and put approximately 6 oz back into the compressor. Note I did not add it to any other components, it all went into the Sanden 508, per their site instructions.
It has worked "ok" and CG suggested there may be still some air in it. I have vacuumed it down twice to "purge" the air but in both cases when I attached the R134 can and bled the common line to the gauge I got OIL coming out! WTH, did I overfill the compressor at 6 oz of ester oil? I did not think the vacuum would pull oil out of the system.

[Coastr]

Not the ac expert around here, but you would always expect to pull some oil out with a vacuum. My vac pump has a sight glass for the vac pump oil and my understanding is that you can see the other oil mixing as you pull gas out.

The oil goes into the compressor but quickly gets distributed throughout the entire system. Hence any leaks showing the dye because the dye mixes with the oil. My daily driver dumped oil all over the floor when the evaporator died and leaked oil through the drain tubes.

Happy to be corrected as I'm always learning in this area as well.

[zippy_gg]

You mentioned a lot of new parts, but you did not list the front and rear condensers... Are they new or did you flushed them thoroughly?
I assume you have a new Receiver/Dryer, but correct me if I'm wrong...

[bob deluke]

There will always be some residual oil in the lines, evap and condenser coil. A vacuum pump only removes water vapor, not oil. As pressure reduces un a vacuum, water changes state from liquid to vapor and pump it out the exhaust. When I worked at Carrier Corp. eons ago, we used large vacuum pumps to pull deep vacuums on commercial systems. If you have a 3 to 5 c.f.m. Pump, a good set of gauges and good hoses on the gauges, try this method. Called double sweep, triple evacuation procedure. Hook up hoses to gauge ports on compressor, evacuate to 30" hug for about an hour. Close gauge valves, take off hose to vacuum pump, hook up to gas side of R134a, break vacuum to "0" pressure on gauge (atmospheric pressure). Shut off gauges, reconnect hose to vacuum pump, turn on pump, open hi and lo side of gauge set, evacuate to 30" hug for about 30 minutes to an hour. Repeat procedure. Last pull down for 3o minutes or so on pump. As you 'sweep' system with clean dry refrigerant, it picks up more water molecules to convert to water vapor. Make sure your vacuum pump oil is clean as well. I change oil in my pump every time I use it. Also, pull out the little Schrader depressors in your line set. They are a restriction to the pump. I think you probably put too much oil in the system. The only way to get all oil out is to open the valves to compressor and blow through with clean dry refrigerant, a no no today. Years ago we used R11 as a cleaning fluid to clean oil out of a system. You're not gonna get the oil out with a vacuum pump. A slight overcharge of oil won't harm the system, just hinders heat xfer as it coats the inside of the coils and lies in the return bends of the evap and condenser coil. Hope this helps...

[bob deluke]

Supposed to be "30"HG (Mercury), not hug. I hate spellcheck........

[db_cooper]

I don't have the book and cannot say for sure..but..I don't think 6oz of oil is sufficient for the entire A/C system. With all the long hoses on a 911, evaporator, condenser and receiver dryer with the compressor I would think it would be closer to 12oz.

How much oil came out of the new compressor? I ask because some compressors that are model specific already have all the oil needed for the A/C system..some don't too.

Pulling a vacuum typically will not remove any system oil, as long as it is sealed with no leaks. Even then it is a trace amount.

When you bleed the service lines on your gauges..you will get some oil spray..usually because there is residual oil in the service lines anyways. It can be messy..it only takes a few cc's of oil to make a mess under pressure.

What problem are you trying to solve? Why do you think there is "air" in the system? Poor system performance?

I love A/C topics on the Pelican.

[88911coupe]

Just to clarify, the r/d drier is new, I have a third condenser and they were all thoroughly flushed with AC flush. In fact I flushed them several times and they all sat in 100 degree sun for about two weeks between flushes. The reason I was doing this was along the lines of Bob's suggestion using refrigerant to pull out the remaining "air" in the system. It was working "fairly" well...I was seeing mid/upper 40 vent temps with upper 90's ambient but I know others were getting into the 30 with same conditions. I should probably leave well enough alone!

[kuehl]

Originally Posted by db_cooper

.I don't think 6oz of oil is sufficient for the entire A/C system. With all the long hoses on a 911, evaporator, condenser and receiver dryer with the compressor I would think it would be closer to 12oz. .

5 to 6 oz is plenty.

Too little, you risk damaging compressor.
Too much, you reduce heat transfer.

[db_cooper]

Kuehl is correct..about 140ml..surprised me..the 928 tales 300ml...http://www.pcarworkshop.com/images/e/eb/Retrofitting_R134a_A-C_1995_680195.pdf

[kuehl]

Yeah, sometimes I get it right.
But... we just want to know where you buried the money, lol.

[db_cooper]

$200,000 just will not go as far as it used to especially when the money bag breaks open.

[kuehl]

I guess it all depends upon what chute he actually used, and whether the bits found were intended to be there.