Automotive Air Conditioning Information Forum (Archives)

jimg on Tue August 31, 2010 5:13 PM

Year: 1990
Make: Nissan
Model: Sentra
Engine Size: 1.6L
Country of Origin: United States

I'm converting from R-12 to R134A on a 90 Nissan Sentra and have a few questions.

1) What PAG oil should I use?

2) The condenser is parallel flow. Can it be thoroughly flushed or should I just buy a new one?

3) How exactly do I purge the old oil from the compressor?

HVargas on Tue August 31, 2010 5:25 PM

1) There isn't really a set PAG oil to use with that compressor since it came with Mineral oil originally. I would recommend using an Ester oil like the one we have here. BVA Auto 100

2) If it is indeed a true parallel flow unit, which would be odd for a 1990 car to have one, you will need to replace it. HECAT has a paper on flushing procedures and I doubt anyone around you have the proper equipment to do it. So the next best option is replacement.

3) To "flush" the compressor, you will want to drain the current oil out, add some oil to it and turn the hub so it spins and cycles the oil through and then drain that and refill it with the proper amount.

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Contact: Arizona Mobile Air

jimg on Tue August 31, 2010 6:17 PM

How much oil do I leave in the system and how much refrigerant????

HVargas on Tue August 31, 2010 6:27 PM

It holds 6.75oz of oil if the system is bone dry. If you are replacing components and aren't flushing the system to bare metal. Any amount I recommend will be a guess at best. A good rule of thumb is to start with 80% of the R12 charge and check your pressures and add accordingly. Factory charge was 33.50oz of R12 so start around 26-27oz and go from there.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: Arizona Mobile Air

HECAT on Tue August 31, 2010 9:19 PM

Quote
Originally posted by: jimg
How much oil do I leave in the system and how much refrigerant????

None

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

jacob_coulter on Wed September 01, 2010 2:18 PM

Any way you can repair it and fill it back with R-12?

I had a car I converted over to R-134 from R-12, and it never cooled that well, I even added two pusher fans on the condensor. I took it to a top AC shop, and they said it was working properly.

I do know I'll never convert over to R-134 if my car originally came with R-12. I'd either pay the R-12 prices, or fill it up with a some sort of "illegal" Propane/butane mix.

jimg on Fri September 03, 2010 11:42 AM

Quote
Originally posted by: jacob_coulter
Any way you can repair it and fill it back with R-12?



I had a car I converted over to R-134 from R-12, and it never cooled that well, I even added two pusher fans on the condensor. I took it to a top AC shop, and they said it was working properly.



I do know I'll never convert over to R-134 if my car originally came with R-12. I'd either pay the R-12 prices, or fill it up with a some sort of "illegal" Propane/butane mix.
Well, I thought of that, but if I ever have to recharge later, I'll need the equivalent of a drug dealer to get R12. I only drive this car (20+ years old, > 360K miles) a few miles a day in the early morning and evening, so getting R12 cold isn't much of an issue. I saw this stuff called freeze12, supposed to be as good as R12 and a R12 replacement, but will it be available 5+ years from now? I keep my cars forever.

jacob_coulter on Fri September 03, 2010 8:52 PM

Quote
Originally posted by: jimg
Quote
Originally posted by: jacob_coulter
Any way you can repair it and fill it back with R-12?







I had a car I converted over to R-134 from R-12, and it never cooled that well, I even added two pusher fans on the condensor. I took it to a top AC shop, and they said it was working properly.







I do know I'll never convert over to R-134 if my car originally came with R-12. I'd either pay the R-12 prices, or fill it up with a some sort of "illegal" Propane/butane mix.

Well, I thought of that, but if I ever have to recharge later, I'll need the equivalent of a drug dealer to get R12. I only drive this car (20+ years old, > 360K miles) a few miles a day in the early morning and evening, so getting R12 cold isn't much of an issue. I saw this stuff called freeze12, supposed to be as good as R12 and a R12 replacement, but will it be available 5+ years from now? I keep my cars forever.

I think R-12 is around $15 a pound now, so it would be around $45 to refill your system. It's still a lot cheaper than properly converting to R-134.

Unless I had some real sentimental value with the car, I'd probably be going to Home Depot and buying some Propane or other alternative to top it off, even though that's "illegal" and "dangerous". A 1990 Nissan Sentra is worth so little, I just couldn't justify the cost for a conversion.

I just know that if I could do it all over again, I wouldn't have converted over to R-134, but if you live in a climate that's not real hot, it's probably a different story.

HECAT on Sat September 04, 2010 9:24 AM

The talk of alternative and illegal products being used as a refrigerant in a MAC system is inappropriate and irresponsible. Please stay within the site sponsors request to offer advice and discussion about the proper and responsible use of R12 or R134a only. The concept of using propane from Home Depot will only end up with gaining you a Darwin Award.

-------------------------

HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

jimg on Tue September 07, 2010 4:00 PM

Quote
Originally posted by: HECAT
The talk of alternative and illegal products being used as a refrigerant in a MAC system is inappropriate and irresponsible. Please stay within the site sponsors request to offer advice and discussion about the proper and responsible use of R12 or R134a only. The concept of using propane from Home Depot will only end up with gaining you a Darwin Award.

I was not agreeing with or condoning the propane path. I was merely attempting to say that the R134A makes more sense for my application than R12.

Edited: Tue September 07, 2010 at 4:01 PM by jimg