A/C Dryer
Do you have to add refrigerant oil to a new dryer, before installing?
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Re: A/C Dryer
According to the Chevrolet Service Manual, additional oil is required for any system components being replaced:
Evaporator - 3 fluid oz
Condenser - 1 fluid oz
Receiver/dryer - 1 fluid oz
For a R12 refrigerant system, use 525 SUS mineral oil. R134a systems use a different oil.
Total oil charge for a dry system is approx 11 fluid oz, which includes the compressor (6 oz).
Larry -
Re: A/C Dryer
What is the fuction of the sight glass,in the dryer?Comment
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Re: A/C Dryer
The sight glass in the receiver/dryer is used to ensure the proper refrigerant charge for the system. An inadequate amount of refrigerant (R12) will show a steady stream of bubbles in the sight glass when the AC is operating. With the correct amount of refrigerant, the sight glass will be clear and no (or minimal) bubbles will be seen.
If you start with a completely empty system, you can also weight the amount of refrigerant added to get the proper charge. Then use the sight glass as a double check. The compressor label and/or the Chevrolet Service Manual lists the correct refrigerant weight for each system. For R12 systems, it is typically around 3 pounds.
LarryComment
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Re: A/C Dryer
When replacing the dryer, have you ever put oil directly in the dryer, before installing? Can you add the required amount of oil yourself to the system,for the dryer change, without servicing the entire system.
Thanks
JimComment
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Re: A/C Dryer
Jim:
Yes. When replacing a AC receiver/dryer, you should add the refrigerant oil directly into the dryer. Then button things up and pull a deep vacuum to remove any traces of moisture from the system and new oil. Ideally, the refrigerant oil should come from a new, sealed can or bottle, but this is not always the case. The dessicant in the dryer will also remove any moisture from the oil.
If you installed the dryer without adding oil, you can go back and add by using one of the small, pressurized refrigerant oil cans that contains a small amount of oil and refrigerant. Add into the low side of the system with the can upside down so the oil flows in. BUT ADD IT SLOWLY so that you do not liquid shock the POA valve or the AC compressor.
These pressurized oil cans hold about 4 oz of oil, so you would only need to add a partial can. You sorta have to guess on the amount, but you can get it close enough. An extra ounce won't hurt anything. I believe these pressurized oil charges are available from places like NAPA or on the internet. Try to get one with only the oil and without the dye or seal conditioner additives (unless you need this feature).
LarryComment
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Re: A/C Dryer
Even though the A/C system is not turned on, is there danger of damaging the compressor just by having the compressor turning, if the oil in the compressor is low? What is the best way to check the oil level?Comment
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Re: A/C Dryer
Jim:
If the AC is off, the compressor is not turning, only the compressor clutch...which has a sealed bearing(s).
One ounce of oil either way is not an issue. There is NO GOOD WAY to determine oil level after the system is charged with oil and refrigerant.
A few years ago, I thought that I might be low on oil due to continued oil leakage at the compressor seal. So I added a 4 oz can of oil. In hindsight, it was probably too much, but I never experienced any known side effects. However, when I connect and disconnect the AC charging hoses, I always get a small mist of oil at the connection....so I know I have plenty! The extra oil also helped free up my sticky POA valve.
According to GM Service Manual, the only way to gauge system oil level is to remove the compressor and empty it into a measuring cup. I don't plan to do that anytime soon.
LarryComment
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Re: A/C Dryer
My system has never been changed over to R134. I think this system has been inoperable for a long time. I was going to add oil but oil for R134 is the only thing available. I am hesitate to add this oil since the system has not been evacuated.Comment
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Re: A/C Dryer
Jim:
If the AC system is inoperable, then it doesn't require any additional oil. Just leave it until you want to fix it up and get it working.
Regarding the pressurized cans of R12 refrigerant oil, they are still available, but you have to search a bit. INTERDYNAMICS Company still has them listed on their website. They are one of many suppliers of this product. See the attached link: http://www.id-usa.com/product.asp? Then go to PRODUCT SEARCH and enter "OC-1". The item you want is their part number OC-1 Compressor Oil Charge for R-12 systems.
DO NOT even think about mixing R12 and R134a oils. You don't want that kind of grief.
LarryComment
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Re: A/C Dryer
Thanks for all of your help Larry. What all is involved with changing over to R134a? Will the compressor have to removed and completely drained of oil,prior to recharging?
JimComment
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Re: A/C Dryer
Jim,
NAPA in Richmond, Va. still carries the R12 Wax-Free Mineral Refrigerant Oil. Part # 209500 for a quart. It's about 6 or 7 dollars a quart.
Regards,
Page CampbellComment
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Re: A/C Dryer
Larry when I had my 85's R12 air conditioner serviced about 12 years ago I was able to stand beside the car a watch. The shop had a machine that they hooked up. The technition removed the R12 in the 85 and also showed me the level of oil that was removed in glass container. He them vacuumed the system down and then installed new compressor oil and R12.
I was going on a long trip and wanted to make sure the system was okay. Some R12 was added, not much. It was plentiful then. I only wanted them to check my R12, did not expect the service I got. The 85 still cools great with its R12.
Only wish that shop was still in business.Comment
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Re: A/C Dryer
Jim E:
Refer to the posts I did a few weeks ago on this topic: June 3, 2008. Subject was originally titled "Off-Idle and A/C Pressure Check". There were two parts, one for R12 and one for R134a. The short answer is that I think that you will be happier staying with R12. But it's an individual choice.
Jim T:
It is amazing what the refrigerant flushing and reclaiming machines can do. However, by 1985, the Corvette AC system had changed a bit from the 1960's design. I am not certain if you had the R-4 compressor yet (I think so), but by this time the receiver/drier had moved to the outlet of the evaporator and was now called an accumulator/drier, the POA valve was gone, and the compressor was controlled by a low pressure cycling switch. My point is that this system MIGHT have been easier to flush and reclaim oil than the earlier A-6 compressors with built-in oil sumps.
Also, R12 and mineral oil are misible (the refrigerant carries the oil mixed with it in a liquid solution) so I am surprised that the machines were able to separate it. Perhaps they removed the refrigerant as a liquid, and then flash distilled or vaporized it to separate the refrigerant from the oil. I am not familiar with the capabilities of this equipment. I guess I still do it the old-fashioned way. Maybe time to change??? But the refrigerant flushing/reclaiming machines are $$$$ for someone who might use them once every five years.
LarryComment
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TerryComment
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