YACT: What's the easiest way to get excess oil out of my AC?

[Shawn]

My car AC used to have a pretty fast leak out of the ac compressor. I used to add a can of r134a every few weeks. I used to get those cans which claim to cool more efficiently. However I didn't realize that they had oil in them and I was adding 1oz of oil each time.

I eventually bought an AC vac and gauge kit and replaced the compressor and receiver/dryer. Even after vacuuming it out I still think I have way too much oil in the system because the system reaches proper operating pressures with less r134a than it should. It works ok but doesn't get as cold as it should. If I add more r134a the compressor will cycle off and on because the pressure is too high.

I was thinking that I might be able to blow a lot of the oil out by fully opening up the high side. If that doesn't work maybe open the low side to air with the compressor on, and build up pressure on the high side then let it out several times. This would probably ruin my receiver/dryer though.

I'm not willing to spend any more money than the $15 it'll cost to refill it with r134a and maybe $30 for a new receiver/dryer, but that's it! No way am I going to take it in anywhere so don't even suggest it.

 

[ValValline]

Are you sure there isn't a restriction in the system? The R134 passes through a fixed orifice (sometimes called an expansion valve) where it is sprayed/metered into the evaporative core. If this orifice is clogged or restricted you will get high pressures on the high side with a partial charge. The cost of replacing this part depends on the make/model, but if you are comfortable tearing your system down yourself it isn't that hard to do.

 

[Shawn]

The expansion valve should be fine. It was replaced a few years ago along with the evaporator core.

 

[ValValline]

Originally posted by: Shawn
The expansion valve should be fine. It was replaced a few years ago along with the evaporator core.

The valve may be fine, but if you had compressor issues it may be plugged with debris. There are some soft parts inside the compressor that can come apart and blow through the system collecting in the tight places like the exp valve and evap core. If you were running too much oil this is even more likely, because a liquid cannot be compressed.

If you are going to go back through the system yourself, then it wouldn't hurt to back flush every part you can with compressed air. This will at least ensure that you have no restrictions. If it was me I would back flush the evap core, exp valve, and condenser. Even if there is no debris this should blow out excess oil. From there you can remove and drain the compressor (upside down on a bench overnight with a rag underneath can do the trick), add the proper amount of oil, then recharge the system.

 

[Shawn]

I was hoping for something I could do without taking everything apart. I don't have any place to work on my car here and I need to use it everyday.

 

[crab]

Originally posted by: Shawn
I was hoping for something I could do without taking everything apart. I don't have any place to work on my car here and I need to use it everyday.

Its what I had to do...except I had front and rear a/c and two evaporators. I still dont think its fully clean.

 

[crosshairs]

I'm assuming you added oil when you replaced the compressor and drier......if not, there is a good chance you are low on oil now.

The compressor holds a good amount of oil, as does the drier.
What type of car is it?

If in fact is does have too much oil, removing the compressor again and draining it would be my choice.

I would check on the type of oil also, all PAG oils are not the same.

Also, the type that comes in the "ready to charge" cans is pretty generic and more than likely not the correct viscosity for your system.

As for your pressure concerns, make sure the condenser fan is operating corectly and that the condenser is free from debris ...

there are many things that will cause pressure concerns, knowing what the pressures are will help me give you a more detailed response if you like.

Are the suction and discharge pressures both high? is one higher than normal while the other is normal?

 

[Shawn]

both the low and high side are normal. i don't remember what they are but they are both came within proper limits once i let some of the extra r134a out. the compressor came with the proper weight PAG oil and I added some to the system like was recommended when I installed it. It's not the same viscosity that's in those cans though. I thought I had gotten all of the old oil out but obviously not.

 

[crab]

What are your pressures?

 

[Shawn]

Originally posted by: crab
What are your pressures?

Around 30/215 IIRC.

 

[crosshairs]

Originally posted by: Shawn

Originally posted by: crab
What are your pressures?

Around 30/215 IIRC.

Whats the ambient temp?
Those numbers are not bad..Whats the air temp out of the vents?

 

[Shawn]

Around 65F or so