R 134A Freon

PopinJohn · Apr 21, 2016

Could someone tell me how many ounces of R134A are required for a 2010 GMC Terrain?

I really don't want to spend $400 for the service manual set just for that piece of information.

I have already installed 12 ounces of R124A and 2 ounces of compressor oil into an empty system.

Gauge readings: High side pressure 120; low side pressure 12; on a 70 degree day here.

Thanks in advance, Mike

Tx Jim · Apr 21, 2016

Gauge readings: High side pressure 120; low side pressure 12; on a 70 degree day here.

Sounds to me as your AC system needs more R134a added. I'd add R134a until high side read 225-250# and then check blower vent temp.

robgIN · Apr 21, 2016

1.43Lb

Jon Hagen · Apr 21, 2016

Shouldn't that info be on an under hood sticker, usually on the radiator support or underside of the hood. ?

JMOR · Apr 21, 2016

(quoted from post at 13:10:57 04/21/16) Shouldn't that info be on an under hood sticker, usually on the radiator support or underside of the hood. ?

think you are answering for some vehicle other than a 2010 GMC Terrain, right?

TGP · Apr 21, 2016

Correct,
It should be somewhere under the hood.
On the Compressor, accumulator, core support, etc.
Tom

n9lhm · Apr 21, 2016

Years ago I spot-checked the pressures in my 1995 Ford Bronco as it was the first vehicle I owned with an R-134A system and wanted to have a baseline reference in case I ever had to service the system. I was amazed that the high side pressure on a warm but not terribly hot day was nearly 400 lbs. I had heard that they run higher than an R-12 or R-22 system but would have been leery to charge it up that high without knowing that was normal.

I just cringe every time I see those Joe Six-pack recharge kits in the auto parts store that is a can of refrigerant and a charging hose with NO gauges or just a low side gauge. Too many people think that every air conditioning problem can be fixed by adding more freon.

Tiger Joe · Apr 21, 2016

yes somewhere on the AC system the tag should be there with the specs. but it could be lost. mine was not on my truck.

high and low pressures both vary based on air temp. However, 12 psi is way too low for low side.

@ 70 degrees you probably want ~35 low, somewhere around 150 high I think.

Also, if you are filling with small 12oz cans you NEVER get the full can into the system. I believe they say knock 1 oz off.

Also are you checking at idle or with the RPMs slightly elevated? AC system are not designed to work their best at idle, so you should take pressure readings around like 12-1500 rpms.

JMOR · Apr 21, 2016

(quoted from post at 13:41:00 04/21/16) Years ago I spot-checked the pressures in my 1995 Ford Bronco as it was the first vehicle I owned with an R-134A system and wanted to have a baseline reference in case I ever had to service the system. I was amazed that the high side pressure on a warm but not terribly hot day was nearly 400 lbs. I had heard that they run higher than an R-12 or R-22 system but would have been leery to charge it up that high without knowing that was normal.

I just cringe every time I see those Joe Six-pack recharge kits in the auto parts store that is a can of refrigerant and a charging hose with NO gauges or just a low side gauge. Too many people think that every air conditioning problem can be fixed by adding more freon.

00? Watch that "I heard" stuff.

Likely way overcharged, as 134a only runs about 10% higher than R-12 and far below R-22. Tiger's numbers are in the ballpark.

Super-H-Mike · Apr 21, 2016

Mitchell On Demand says its 1.43 lbs.

jimg.allentown · Apr 21, 2016

As previously stated, there should be a sticker or plate under the hood somewhere that has that information on it. 1.43 lbs. is about 22 and 1/2 ounces. Two of the 12 ounce cans should be sufficient. The best way to tell if your system is correctly charged is when the outlet end of the evaporator starts to sweat. That tells you that evaporation is just finishing as the refrigerant exits the evaporator.

As to gauge readings, the 400psi that the other fellow mentioned is not out of the ball park. That is one reason that the R-134a systems have a high pressure cutout switch on the high side. R-134a does not behave in the same way as R-12. High side pressures can skyrocket for any number of reasons without there being something wrong with the system. Modern systems are much smaller than older systems, and with less volume in the system, pressures can rise very rapidly with little changes in the system. Also, many systems now cycle the electric fans with the A/C. Pressure on the high side can go quite high until the fan comes on.

Latest buzz is that they now want to replace R-134a with something else. What I heard was R-600. Hope not, because that stuff is highly flammable.

Jon Hagen · Apr 21, 2016

Something was wrong with the Bronco, high side pressure should never get near 400 psi unless way over charged or no / poor air flow through the condenser. All the factory 134a systems I have owned and those converted from R12 to R134a, run maybe 10% higher pressure than R12.

n9lhm · Apr 21, 2016

That's interesting. I was commenting the other day that I'd had that vehicle for 21 years and never had to touch the air conditioning! It's always worked fine.

guido · Apr 21, 2016

Hello popinjohn,

@70 degrres F. Low side 35 40# high side 145 160#. Low side should be sweatting up to the compressor. That is a better I dicator of proper charge then pressure.
If you see frost, then is a bit too much........

GUIDO.

n9lhm · Apr 21, 2016

"Hope not, because that stuff is highly flammable."

Hope it's not propane

Den N Ms · Apr 21, 2016

popinjohn You say,I have already installed 12 ounces of R124A and 2 ounces of compressor oil into an empty system.
Your A/c system uses R134 and it should not be mixed with any other type of refrigerants.

HCFC-124 may be used by itself as a pure refrigerant to replace R-114 in some applications, although its vapor pressure is somewhat higher than that of R-114. In addition, when replacing R-114 with HCFC-124, significantly higher refrigeration capacity will be encountered. This may result in electrical overload of the motor unless precautions are taken. The expansion device may also need to be modified
Refrigerant

PopinJohn · Apr 21, 2016

R124 is a typo on my part, should have read R134.

Anonymous-0 · Apr 21, 2016

124/134/195?.....guess what? with the kind of advice/conflicting OPINIONS and lack of facts, you will never get it right if you follow this crowd!!!!!!!!!!!!!!!!!!!
uugh!

Den N Ms · Apr 21, 2016

R-1234yf Refrigerant
Auto makers are slowly moving toward a new refrigerant for automotive air conditioning systems. The new refrigerant is R-1234yf (HFO-1234yf), and it will be phased in slowly over time.
R-1234yf has cooling performance that is similar to R-134a but not quite as good. It is about 5 percent less efficient than R-134a. It is not a simple drop-in substitute for R-134a because it requires a slightly larger or more efficient condenser and a more robust leak-resistant evaporator (for safety). R-1234yf also requires a new type of compressor PAG oil, as well as new J2843 certified recovery and recycling equipment designed especially for the new refrigerant. And here is the punch line: R-1234yf is significantly more expensive than R-134a ($100 per pound versus about $10 per pound!). Prices are expected to come down as production ramps up in the years ahead to meet a growing demand.

JMOR · Apr 21, 2016

(quoted from post at 17:55:01 04/21/16) R-1234yf Refrigerant
Auto makers are slowly moving toward a new refrigerant for automotive air conditioning systems. The new refrigerant is R-1234yf (HFO-1234yf), and it will be phased in slowly over time.
R-1234yf has cooling performance that is similar to R-134a but not quite as good. It is about 5 percent less efficient than R-134a. It is not a simple drop-in substitute for R-134a because it requires a slightly larger or more efficient condenser and a more robust leak-resistant evaporator (for safety). R-1234yf also requires a new type of compressor PAG oil, as well as new J2843 certified recovery and recycling equipment designed especially for the new refrigerant. And here is the punch line: R-1234yf is significantly more expensive than R-134a ($100 per pound versus about $10 per pound!). Prices are expected to come down as production ramps up in the years ahead to meet a growing demand.

t just keeps on getting 'better'.

jimg.allentown · Apr 21, 2016

Funny you should mention propane. Actually, R-12 was developed to emulate propane without the flammability. There are all kinds of gases that can be used as refrigerants. Propane is actually an excellent refrigerant if not for the flammability issue. So also is sulfur dioxide and even carbon dioxide. Both have been used in refrigerant systems in the past.

Geo-TH,In · Apr 21, 2016

There used to be a sight glass on top of the filter dryer. Add until all the air bubbles are gone. Then look at suction pressure. The suction should have a temperature above 32. The temperature scale on some gauges are in Celsius.

jimg.allentown · Apr 21, 2016

We were told that same "shuck and jive" story when R-134a was coming in to replace R-12. Seems that they were wrong, as the R-134 works in R-12 systems with a change of oil. We were told of different components being required. Found out that the R-12 systems (1993) had the SAME PARTS as the R-134a systems in 1994.
Also note that many of the current systems use the PAG oil as it is. Some do use the ester oil, but those oils are compatible with each other as far as I know.

The bottom line is FOLLOW THE MONEY!!! As I see it, the only reason to eliminate R-12 was that DuPont's patent ran out and they could no longer collect royalties on every ounce sold or produced. I would bet on the same reason to phase out R-134a. BTW, a couple of things....
R-134a is actually TEFLON GAS. They expose it to high pressure and temperature to polymerize it to stick to our frying pans.
Also, Freon is a registered DuPont trademark. R-134a is REFRIGERANT, not FREON!

MarkRobke · Apr 21, 2016

My fast guess would have been 1 1/2 cans.Tx Jim has the best touchy feely answer,and someone else gave an amount,which your vehicle should have under the hood somewhere,usually on the compressor.The system should have been evacuated first,but none the less,as well as watching your pressures,watch your outlet temp in the your duct louver in the dash.It should be right around 40* on a 70* day.Your low side pressure should be close to 35 or 40.For best results keep your engine rpm at 1000 or 1100 while charging.Mark

Jon Hagen · Apr 21, 2016

it's amazing how well some are sealed. My oldest R134a rig is my 2000 Dakota at 16 years and never topped up on refrigerant, your rig at 21 years tops that. My all time champ is the little Steiger KR1225 I bought new in 86, The ac still works after 30 years without ever being topped up. This is an old R12 system.

Tx Jim · Apr 21, 2016

(quoted from post at 18:14:50 04/21/16) There used to be a sight glass on top of the filter dryer. Add until all the air bubbles are gone.

I was taught if sight glass is completely clear of bubbles when using R134A that system had too much R134A in it.

NCWayne · Apr 21, 2016

You didn't mention doing so, and only one other post I was mentioned it, but if the system wasn't vacuumed out first, NONE of the information given is relevant. In fact without the air out of the system your going to have problems regardless of whether you get the right amount of refrigerant in the system or not. In fact you'll be lucky to get the right amount of refrigerant because, basically, the air takes up a lot of space.

That said, the high side will probably run around 250 plus, and the low side around 120, plus or minus. If you put a gage in the air vent it will read somewhere around 45 degrees when it's cooling properly.

I do a good many equipment systems, and rarely do I have any idea how much the system is supposed to hold, nor am I going to spend $600, per machine, for a manual, just for that info. I've been using the above numbers as a reference for nearly 15 years, and thus far have never had an issue.

Jon Hagen · Apr 21, 2016

Are you sure about 120 psi on the low side of a R134a system. In my experience ,low side pressure is generally 20-40 psi tops ???

Bob · Apr 21, 2016

Yep, R134A is not even called FREON, so from the post title on down there's lots erroneous info, not to mention 120 psi on the low side GOOD LORD!

Hobo,NC · Apr 22, 2016

(quoted from post at 10:57:18 04/22/16) Yep, R134A is not even called FREON, so from the post title on down there's lots erroneous info, not to mention 120 psi on the low side GOOD LORD!

Whut he said, Bob l don't want to step in this pile of chit its all yours...

Hobo,NC · Apr 22, 2016

Maybe with the new stuff it will scare away the DIY'er..

https://www.motor.com/magazine-summary/really-right-refrigerant-finally-arrives-april-2016/

You can bet the farm there will be plenty of mix'N going on...

It became pretty obvious that an R-1234yf system that had lost its charge could be retrofitted to R-134a at far lower cost for refrigerant (R-134a is running about $3/lb. and up; R-1234yf retail is in the “up to $164/lb.” range). Daimler gave away that “secret” when it complained that R-1234yf was unsafe, pulled the R-1234yf out of those cars containing it and recharged them with R-134a.

dhermesc · Apr 22, 2016

I know of several tractors that never had anything changed (including the oil) and simply had the adaptors put on when they were changed from R12 to R134a and they went on for years of use.

GeneMO · Apr 22, 2016

I still have a couple of cans of the old R-12 laying around the shop somewheres.

My dad's 1977 Ford F-150 has been parked in the shed for bout 10 years now. Needs the carb replaced, which I have a new one in the box, just need to put it on.

Wonder if that A/C will still work?

Gene

Hobo,NC · Apr 22, 2016

If it don't make sure the window cranks work freely... Those were not a good candidate for a retro fit unless you changed the compressor to a Sanden and a few other mod's BTDT...

I drive my 77 F350 1K miles a year I deal with the heat no more than I drive it... If I had to drive it more I would fix the AC are get another truck with good air because it is one hot SOB in the summer...

I have seen a few Fords of that vintage trashed when left outside for a long time,,, water leaks onto the air cleaner runs by the wingnut that holds the lid on the air cleaner assy and fills the engine with water..

R 134A Freon

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