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no oil need advice

glenhart on Fri April 15, 2011 3:41 PM User is offline

Year: 2004
Make: Chevrolet
Model: Impala
Engine Size: 3.4L
Refrigerant Type: R134a
Country of Origin: United States

Bought used car and was told Tuffy auto repair diagnosed the AC and said it needed a new condenser. I am replacing the condenser and receiver/drier and when I tried to empty the condenser, after turned it with connections on bottom I was only able to see about a small 3 inch puddle of oil with very light green color. I also drilled a hole in receiver/drier and could not get a drop of oil out of it. Now my question is should I add 8 oz. of PAG46 oil as this is system capacity, or should I just add 3 oz. as suggested elsewhere in this Forum? Also what is the normal repair shop proceedure for testing for leaks, and might they have flushed the system, therefore removing oil? One other question is my system calls for 37 oz. If I just use 3 - 12 oz. cans and add the 1 oz of liquid uv dye when installing receiver. Is that enough freon or should I try to get the extra oz of freon out of a new can? How would I know when to stop if so? Thank you in advance.

Walter69 on Fri April 15, 2011 10:28 PM User is offlineView users profile

I'm pretty new to this, but maybe by trying to help you, I can find out how much I've learned from this site! Trying to empty the condenser... it shouldn't be full of oil. A 3 inch puddle, well... AC systems need precise, measured amounts of gas (freon) and lubricant. A 3 inch puddle is far too vague an amount. Anyways, when you took out the condenser did you notice it was oily and green? Did Tuffy's mean that the condenser was leaking or clogged up when they say it needed to be replaced. I'm hoping clogged because you probably would have noticed oil and dye on it, right? I hope you don't have the condenser and evaporators mixed up. Do some research in the forum and you can find very good tutorials about air conditioning systems in general, automotive a?c systems, and lastly, you can search your specific vehicle both here and on the web for capacities and valuable tips. Your ques. about how much oil, that Tuffy's place should have diagnosed and got the go ahead to proceed with the repair before any flushing was done. You don't need to add dye unless you are trying to find leaks. 37 oz. well, put in three cans and be an oz. short, or, get a scale and weigh the fourth can. Close the valve after it drops an oz. You can buy oil that comes mixed with gas in the can. In fact, smaller amounts of gas than 12 oz. I was about to read some posts about how the oil is added so I'll stop there. Most importantly, if you want to fix this yourself and do a good enough job, make sure you understand more about a/c systems before you start wrenching. Working with refrigerants and compressed gases can be dangerous. Maybe you can follow my thread and learn? Oh, yeah, that receiver drier you drilled a hole into, I think it has some stuff called "desiccant" in it which might absorb any oil that gets to it. If it is after the evaporator and before the compressor, (talking normal flow, should say "between" them probably) then it is an accumulator and may or may not have much oil in it depending how close it is to the compressor. It will still have desiccant in it though. Wait a minute, now I'm confused. I might have that backwards. Receiver/driers are like gas and liquid separators and prevent condensed gas (liquid form) from reaching the compressor. Hence the name "drier". You don't want the compressor to try to compress ANY liquid because of the hydraulic property of liquids (they do not compress like gaseous states of materials). The compressor could abruptly stop or "lock up" and that's not good. An accumulator is the vessel placed shortly before the evaporator which like the rec/drier, separates the liq. and the gas and sends only condensed refrigerant to the orifice tube. In fact, txv's (thermostatic expansion valves) and orifice tube systems utilize one or the other, I think. Did I just hijack this mans thread? Just want you to learn more about how systems work so you will better understand my answers to your questions. Whew! That was kinda long, sorry. I'll go post in my thread now. Good luck sir!

Edited: Fri April 15, 2011 at 10:51 PM by Walter69

mk378 on Fri April 15, 2011 11:48 PM User is offline

I'm guessing they found the condenser has a leak, either from road debris or simple GM fallapart. Thus you had zero pressure when taking the lines apart. Inspect the old condenser for signs of damage or oil/dye leakage. I don't like going on a thirdhand diagnosis from a place that isn't an expert in the first place, but since you've already taken it apart you kind of have to now.

The green dye is one major method to find leaks, it lights up brightly under UV light (blacklight). Big leaks can also be found simply by charging a small amount of refrigerant or nitrogen and listening to it hiss out. Flushing the system requires taking it all apart so they wouldn't have done that. If the car has gone for a long time with no pressure and a hole in the condenser you might consider flushing, or at least pulling the compressor off the car and changing the oil in it. PAG oil absorbs water when exposed to moist air. The waterlogged PAG has poor lubricating properties.

Don't add a whole oz of dye. There are cans with 12 oz R-134a and 1/4 oz UV dye, you could use one of those as the first can you charge in. The rest plain R-134a.

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