R134
08-31-11, 05:33 PM
#1
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R134
I'm putting freon on my 98 gs300, does anyone know what is the proper reading to let me know when to stop filling the ac with freon. Also, how can I tell when the can is empty.
08-31-11, 08:28 PM
#3
In general, the high side should be just under 2.5x ambient temp. So, if your ambient air temp is, say, 90 degrees, and the engine RPM at cruising (maybe 1500?) high side pressure should be just under 225psi. For low side, something about half of ambient temp should be about right. so, for 90 degrees, 40-45 psi.
Last edited by tinman; 08-31-11 at 09:46 PM.
09-01-11, 11:18 AM
#4
im here john....
By proper reading are you talking about the low side and high side pressure? I assume you have a recharge bottle with a pressure gauge?
In general, the high side should be just under 2.5x ambient temp. So, if your ambient air temp is, say, 90 degrees, and the engine RPM at cruising (maybe 1500?) high side pressure should be just under 225psi. For low side, something about half of ambient temp should be about right. so, for 90 degrees, 40-45 psi.
In general, the high side should be just under 2.5x ambient temp. So, if your ambient air temp is, say, 90 degrees, and the engine RPM at cruising (maybe 1500?) high side pressure should be just under 225psi. For low side, something about half of ambient temp should be about right. so, for 90 degrees, 40-45 psi.
if the temp outside is 90 degrees the high side should be ABOUT 104.2 with r134a (keep in mind pressure will fluctuate with temp but not by 120 psi).BTW in order for the high side psi to EVER CORRECTLY be 225 the outside temp should be someplace around 137-140 degrees outside
your low side should NEVER be 40-45 psi UNLESS you have a 45-50 degree evaporator temperature which would mean your not cooling well....at 35 degree evaporator temp your psi should be around 30.3 (again keep in mind pressure will fluctuate with temp)
for easy reading they make pressure/temperature charts guys (i have one on my desk that can do R22,R134A,R404A,R408A,R409A, and R410A. my testo digital manifold (yes i have gotten lazy after doing HVAC for 10 years and i went digital) has the calculations for pretty much EVERY freon/temp needed
Last edited by sakataj; 09-01-11 at 12:00 PM.
09-01-11, 11:55 AM
#5
WOW.... where do u learn this stuff? i know you normally helpful but i wish people on this forum wouldn't talk if they dont know what they talking about ESPECIALLY when it comes to HVAC about something that can really destroy/damage vital parts of your car
if the temp outside is 90 degrees the high side should be ABOUT 104.2 with r134a (keep in mind pressure will fluctuate with temp but not by 120 psi)
your low side should NEVER be 40-45 psi....at 35 degree evaporator temp your psi should be around 30.3 (again keep in mind pressure will fluctuate with temp)
if the temp outside is 90 degrees the high side should be ABOUT 104.2 with r134a (keep in mind pressure will fluctuate with temp but not by 120 psi)
your low side should NEVER be 40-45 psi....at 35 degree evaporator temp your psi should be around 30.3 (again keep in mind pressure will fluctuate with temp)
You may read:http://www.firstfives.org/faq/AC/ac_charge.html
Quote: "A good rule of thumb with R134a is to run fan on High with all windows open and engine at 1500 rpm. High side pressure in PSI should be about 2.2 to 2.5 times outside air temperature in degrees F. Example if it's 90 degrees F, high side should be no higher than 225PSI."
And http://www.tahoeforum.com/showthread.php?t=10191
here is a guy using the same kinda over the counter recharge kit i assume the OP is using: "So I get r-134a w/ subzero synthetic a/c booster with psi gauge. bottle say for ambient air temp psi should be 45-55"
And from here: http://www.aa1car.com/library/ac_recharging.htm
Quote: "High pressure gauge: When the reading gets up around... or 225 to 250 psi (R134a), STOP. The system is fully charged and should be cooling normally. DO NOT add any more refrigerant"
There is also an ehow on how to do this: http://www.ehow.com/how_5660133_recharge-auto-ac.html
Quote: "The gauge readings on a fully charged system will be 35 psi to 45 psi on the low side and 200 psi to 350 psi on the high side."
350 is a bit high, but if you are in a VERY hot day, say 110 like we get here in the Chicago area from time to time, can happen in short bursts with a surge in RPM.
As you can see, r134a requires higher pressure. This is true for all cars. r134a has a standardize system, at least more standardized than r12, and this allows for everyone's car to take the same oil, the same refrigerant, use the same type of pipes, and buy their recharge kits from the store (and it's less harmful to the environment. ) Because of these reasons it doesn't require a license to use. But it takes a little more energy to run because it requires higher pressures to achieve the same air discharge temp because it's not as effective.
Edit: I just looked up the factory service manual for my SC. Oddly, it doesn't say what psi to use. It says to add until the bubble disappear in the little window by the nozzle. Maybe I have an old manual but this one is from 1997, R134a was in full swing by that time (mandatory by 1995).
Last edited by tinman; 09-01-11 at 12:14 PM.
09-01-11, 12:10 PM
#6
this is what i do for a living, im 100% sure of my numbers (i can even scan/load you a pressure chart man since claim some random info off the internet knows the right answer) by all means you can do whatever you want to and charge to whatever pressure/temperature you want. The OP can listen to you,me or not at all....it makes no difference to me, my air in my car works great.....its charged to 31.8 PSI with r414b (which is a direct drop in for R134)
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09-01-11, 12:36 PM
#8
although i went back and edited my post some my numbers stayed the same. the numbers/psi's i listed ARE correct.... hate to break it to you but the "tool" you have in your garage is incorrect btw what "tool" is this?
this is what i do for a living, im 100% sure of my numbers (i can even scan/load you a pressure chart man since claim some random info off the internet knows the right answer) by all means you can do whatever you want to and charge to whatever pressure/temperature you want. The OP can listen to you,me or not at all....it makes no difference to me, my air in my car works great.....its charged to 31.8 PSI with r414b (which is a direct drop in for R134)
this is what i do for a living, im 100% sure of my numbers (i can even scan/load you a pressure chart man since claim some random info off the internet knows the right answer) by all means you can do whatever you want to and charge to whatever pressure/temperature you want. The OP can listen to you,me or not at all....it makes no difference to me, my air in my car works great.....its charged to 31.8 PSI with r414b (which is a direct drop in for R134)
Another source... I know it's just an Internet source, but there is more information here. Fast forward to 1:30. You will see the pressure gauge which gives acceptable pressures for the A/C system. It is exactly what I said for the low side, 30 psi - 50 psi is normal It even has little numbers below it for ambient temp. http://www.youtube.com/watch?v=UTa4f7UUqzA
The numbers I gave are standard numbers for doing this. They are referenced all over. They work great.
Last edited by tinman; 09-01-11 at 12:52 PM.
09-01-11, 12:57 PM
#9
Maybe the difference is because my instructions indicate the engine should be operating at 1500-2000 RPM? Are your numbers at idle? My A/C works great too. The 4 random posts I listed were top hits this information is readily available. I didn't come across any info that said it should be 120 psi on high side
I've always used 2.5x high, 0.5x low. That's how I learned it.
I've always used 2.5x high, 0.5x low. That's how I learned it.
i gave the correct info to the OP he can accept it or reject it. again this is what i do for a living,YES my #'s are at 1500-2000 RPM. what is it you do for a living and how often are you charging ac's in cars or elsewhere?
BTW im still waiting to know what your "tool" in the garage is
09-01-11, 01:02 PM
#10
The tool in my garage is a dual gauge setup with a mount hook for the hood. One side is red and plugs into the high side, and other gauge is black and plugs into the low side. It can measure pressure or vacuum. It's not a very advanced little device, I know. But it works for me. Kinda looks like this but smaller. http://www.aircondition.com/tech/questions/82/ It has little green, blue, yellow and red zones showing pressure for r134a as it relates to ambient temp (just like the video above) My father purchased it in the late 90's and gave it to me some years ago.
This page also gives the same information for the psi readings for low and high. I've now provided 6 sources. I doubt 60 would change your mind. I guess we'll have to agree to disagree on this one. I'm not arguing for the sake of arguing. I wanna know the truth. I'm satisfied over the course of this conversation that I have found the answer. 5 Internet sources, manufacturer recommendations on the bottles, my own use, my own tools, and what I know about the rule of thumb (2.5x, 0.5x) are all consistent.
This page also gives the same information for the psi readings for low and high. I've now provided 6 sources. I doubt 60 would change your mind. I guess we'll have to agree to disagree on this one.
I'm not arguing for the sake of arguing. I wanna know the truth. I'm satisfied over the course of this conversation that I have found the answer. 5 Internet sources, manufacturer recommendations on the bottles, my own use, my own tools, and what I know about the rule of thumb (2.5x, 0.5x) are all consistent.
Last edited by tinman; 09-01-11 at 01:22 PM.
09-01-11, 01:38 PM
#12
no 60 wrong sites WOULDN'T change my mind. here let me show you TWO sites (one being fluke a NATIONAL very well known HVAC tool company) that disprove you and your internet theories.
http://www.prochiller.com/reFrigtempChart.html
http://assets.fluke.com/appnotes/ele...r/1265816_.pdf
if u wanted the truth you would have googled a temperature/pressure chart not the junk u did google. i'm really through now, BTW if u wanna know the truth call a local HVAC supply house and ask them.
here is a johnstone supply (the same national company i have worked for,for the last 10 years just in a different city) near by you, if u dont trust them call another competitor
5365 Walnut Avenue
Downers Grove, IL 60515
(630) 427-6200
http://www.prochiller.com/reFrigtempChart.html
http://assets.fluke.com/appnotes/ele...r/1265816_.pdf
if u wanted the truth you would have googled a temperature/pressure chart not the junk u did google. i'm really through now, BTW if u wanna know the truth call a local HVAC supply house and ask them.
here is a johnstone supply (the same national company i have worked for,for the last 10 years just in a different city) near by you, if u dont trust them call another competitor
5365 Walnut Avenue
Downers Grove, IL 60515
(630) 427-6200
09-01-11, 04:55 PM
#13
OH! Oh dear. I think I see the error. The sites that you are posting have information about central A/C systems. You stated that I should have started out by searching for r134a temp charts. I did. I discounted the ones that were for central HVAC. Are you certain that the chart is for automotive A/C? Because it doesn't look like it. Home A/C systems seem to run lower pressure than automotive (based on the charts I've seen online. I'm not a pro). For example., this chart confirms your numbers: http://www.prochiller.com/reFrigtempChart.html However it is for central HVAC systems (I didn't even know they used R-134a). I came across that when I was doing my own research some years ago and I wanted to know if the gauge I have could work on home systems too.
You don't have to believe me. Believe Lexus. This is the Lexus GS second generation factory service manual for the GS300. This is exactly the car in question:
You may convert MPa to psi here: http://www.chapelsteel.com/mpa-psi.html
The low side is a little low, it's mid way in between our two numbers, but the high side is spot on for my information. I believe the information you posted is for a different application. Automotive pressures would seem to run higher. You now have all the evidence above and the factory service manual itself.
You backed me into a corner by starting out saying that I should only post what I know about. That put me in the position of defending my position or walking away. I know it's silly, but seeing you say that to people has gotten a little under my skin. You can't blame me for defending myself. The information I posted is correct. I stand by it and it seems Lexus does too.
You don't have to believe me. Believe Lexus. This is the Lexus GS second generation factory service manual for the GS300. This is exactly the car in question:
You may convert MPa to psi here: http://www.chapelsteel.com/mpa-psi.html
The low side is a little low, it's mid way in between our two numbers, but the high side is spot on for my information. I believe the information you posted is for a different application. Automotive pressures would seem to run higher. You now have all the evidence above and the factory service manual itself.
You backed me into a corner by starting out saying that I should only post what I know about. That put me in the position of defending my position or walking away. I know it's silly, but seeing you say that to people has gotten a little under my skin. You can't blame me for defending myself. The information I posted is correct. I stand by it and it seems Lexus does too.
Last edited by tinman; 09-01-11 at 05:04 PM.
