How much Freon do i need?

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v-wiz
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How much Freon do i need?

Post by v-wiz »

Hey guys, how much Freon will my 81 628csi need? just about all my cooling parts are new, but i think my system might be over charged. I would think it should be the same for all pre 82 cars right? If anyone has the sticker indication on the car can you please let me know. Thanks guys. :D
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dwcains
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Re: How much Freon do i need?

Post by dwcains »

I believe the early cars had an R12 charge of 975g +/- 25g.
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Re: How much Freon do i need?

Post by v-wiz »

dwcains wrote:I believe the early cars had an R12 charge of 975g +/- 25g.

Thank you.. And if it were R134?
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Re: How much Freon do i need?

Post by dwcains »

I've got a friend who's an a/c tech, and he's always used (R12 pounds X 0.9) - 1/4 pound = R134a pounds.

975g = 2.15 pounds

(2.15 pounds x .9) = 1.94 - .25 = 1.69 pounds R134a
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v-wiz
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Re: How much Freon do i need?

Post by v-wiz »

dwcains wrote:I've got a friend who's an a/c tech, and he's always used (R12 pounds X 0.9) - 1/4 pound = R134a pounds.

975g = 2.15 pounds

(2.15 pounds x .9) = 1.94 - .25 = 1.69 pounds R134a

Thanks Dean. I will run this by my A/C guy and see where we get at.
:D
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Re: How much Freon do i need?

Post by dwcains »

My friend is really old school, so he has his ways, and I'm sure other a/c guys do, too. But he sure seems t know what he's doing, and his shop is always packed.
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Re: How much Freon do i need?

Post by v-wiz »

Thanks again..

I brought my car over to the A/C tech over the weekend. I told him that it may be overcharged. He evacuated the unit, pressurized it and recharged at about 1.6 pounds.
I just wish it blew out colder air. He did say the low side is at about 50.
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Re: How much Freon do i need?

Post by Pod »

v-wiz wrote:Thanks again..

I brought my car over to the A/C tech over the weekend. I told him that it may be overcharged. He evacuated the unit, pressurized it and recharged at about 1.6 pounds.
I just wish it blew out colder air. He did say the low side is at about 50.
I thought 200-225 high side and <40 low side are the optimal pressures :-k
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Re: How much Freon do i need?

Post by v-wiz »

Pod wrote:
v-wiz wrote:Thanks again..

I brought my car over to the A/C tech over the weekend. I told him that it may be overcharged. He evacuated the unit, pressurized it and recharged at about 1.6 pounds.
I just wish it blew out colder air. He did say the low side is at about 50.
I thought 200-225 high side and <40 low side are the optimal pressures :-k

He did say 40's are good, but it wasn't there. So something may be wrong?
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Re: How much Freon do i need?

Post by dwcains »

I've been convinced for long time that R134a simply isn't a suitable substitute for all systems made to work with R12 originally. Maybe it's the orifice valve, the compressor, or just the combination of a few things, but It's always less than ideal. If you can't get R12, I'd suggest charging with R152a, which is very similar in its characteristics to the original refrigerant, and in some ways even better. And, it's already becoming the refrigerant of the future in new cars, along with 1234YF.
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Re: How much Freon do i need?

Post by v-wiz »

What im beginning to realize is that the blower just sucks really bad, it barely blows air out the vents if at a stand still. Once the car gets moving i get more air coming in. There has to be a retrofit blower motor out there...
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Re: How much Freon do i need?

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v-wiz wrote:What im beginning to realize is that the blower just sucks really bad, it barely blows air out the vents if at a stand still. Once the car gets moving i get more air coming in. There has to be a retrofit blower motor out there...
If the motor works better with the car moving - and I presume with the engine turning over faster - sounds to me as if the charging system could be at fault :-k
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Re: How much Freon do i need?

Post by Pod »

dwcains wrote:I've been convinced for long time that R134a simply isn't a suitable substitute for all systems made to work with R12 originally. Maybe it's the orifice valve, the compressor, or just the combination of a few things, but It's always less than ideal. If you can't get R12, I'd suggest charging with R152a, which is very similar in its characteristics to the original refrigerant, and in some ways even better. And, it's already becoming the refrigerant of the future in new cars, along with 1234YF.
Interesting post! I've owned American cars for many years, when very, very few European cars even had a/c as an option. I've had many cars with R12 which I never had to get recharged. Just as well, as it was very difficult to find anybody over on this side of the pond who could do it! I read that is it "normal" for a R134A system to lose 10-20% of its charge each year. R134A used to be lauded as the "safe" alternative to R12, but now we hear that it is not (and as mentioned, it is more prone to leakage!).

I wonder if the new "safe" alternative will be any better, or will they be telling us in ten years that they got it wrong again!
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Re: How much Freon do i need?

Post by dwcains »

Converted R134a systems in older R12 cars leak because the original hoses are more permeable to the R134a's smaller molecular size. A "proper" conversion involves installing "barrier" hoses to prevent this issue. As for the environmental issues, which involve depletion of the ozone layer, I've always wondered how such a large, heavy molecule as R12 gets all the way up to the ozone layer.
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Re: How much Freon do i need?

Post by Pod »

dwcains wrote:Converted R134a systems in older R12 cars leak because the original hoses are more permeable to the R134a's smaller molecular size. A "proper" conversion involves installing "barrier" hoses to prevent this issue. As for the environmental issues, which involve depletion of the ozone layer, I've always wondered how such a large, heavy molecule as R12 gets all the way up to the ozone layer.
Totally understood. However, I'm not referring to converted R12 systems - I'm talking about those which originally were designed for, and had, R134A - but still leak.
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Re: How much Freon do i need?

Post by dwcains »

Hmm, that's a problem I haven't experienced, but since R134a became the standard, my wife and I have only had Japanese cars as our primary vehicles. Her current 2007 Acura and my 2008 Nissan still have ice-cold a/c, and no recharges needed.
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Re: How much Freon do i need?

Post by sansouci »

I'm following Song's program and putting in a new condenser, new compressor (genuine Sanden SD514 p/n 6668), receiver dryer, revamped/rebuilt hoses, but leaving the old evaporator under the dash board. I've seen some mods to the side of the console such that the squirrel cages can pick up more air. I will also do a modest window tint. Rather than using the old condenser fan, I am looking at the flex-a-lite fans which have more modern blade design than a 1980's fan.
I have some expectations that there will be an improvement. If not, the evaporator gets changed, too. Total budget for equipment, supplies and labor: about $1k. The parts pile is growing and hope to get under the car soon.

As a note on the Sanden compressor: I found the engineering drawings on the Sanden website and found some useful information. The Sanden 508 is an older design for R-12 while the 5H14 is for R-134a. Also there are two relevant variants: the p/n 6668 is designed for a max RPM of 7000 rpm and a continuous 6000 rpm while the p/n 6664 is designed for 4,000 and 4,000 respectively. I suspect the seals may be different. While I have don't have an M and not likely to hit 6,000rpm, I just thought it makes a little more sense for durability.
As to hoses, I am either going to rebuild the fittings with Gates barrier hose or use Aeroquip EZ clips with GH134 hose.
--Ken

The story seems to be getting a little murkier. Sanden makes an aftermarket model CO4510C which according to them "replaces 4509,4510,4644,6626,6664,6668" So I am asking my supplier to contact both his distributor and/or the regional branch of Sanden to either clarify it or get the specific model.
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Re: How much Freon do i need?

Post by zinnocoupe »

sansouci wrote:
The story seems to be getting a little murkier. Sanden makes an aftermarket model CO4510C which according to them "replaces 4509,4510,4644,6626,6664,6668" So I am asking my supplier to contact both his distributor and/or the regional branch of Sanden to either clarify it or get the specific model.
---Ken
Ken, I've following Song and watching the A/C posts and yes, it seems to me AC is very murky and complicated. I'll be doing this someday :-?
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