Does Acura have a specific R134a refrigerant pressure chart or are the generic ones floating around the net ok to use? Also what should the static pressure be in a "normal" 3rd gen TL A/C system (A/C not running).

 

Not really certain as to the static pressure as that is also ambient temperature dependent, but I'd say @ 90. Our '11 Turbo Kia was @ 100, at least that's what it read when I replaced the compressor, hot day.
The chart looks like normal values, but when the car was running (Turbo Kia again), I was able to get colder temps out of the system than what the chart indicates, but it's good for a reference.
Personally if doing the system over, I'd discharge, evacuate then add refrigerant by weight so one can know the correct amt. in the system.

 

Thanks. Its about 67°F with 80% RH today so I got the pressure to low 25 and high 140. Enough to get the AC to cool. I'l probably have to replace the compressor later this year. I've already replaced a clutch and coil on it.

 

Might want to get a stick thermometer and use it in the vents to check temp.

 

43° to 44.4° at the vents, got to recheck on a warmer day.

 

 

In the chart example above, if I read it correctly, it is saying that if the ambient air temp is 86 degrees, then it is in Normal operating range if the output is 63 degrees. That does not sound like it is cooling that great to me. I saw a person on YT say his AC was like 45 degrees.
And I am also guessing the "intake pressure" is the Low Side ?? And the "Delivery pressure" is the High Side?? (let me know)
Based on all the instructions and the chart, you sure have to observe and follow every detail to get an accurate analysis of your system. Like run the AC for 10 minutes and raise the idle to 1500 and do not sit in the car, then based on Temperature and humidity, your output should be X... lovely.

What if we simpliy this drawing and remove the High Side pressure stuff?? (I do not have the equipment or experience for that anyway)
So, let’s assume your AC is working and no bad parts
Lets also assume today is 95 degrees, or at least the air going into the system is 95.

Does this Look right to you? It indicates the Low Side pressure (aka intake pressure?) can range anywhere from approx 35.5 to 56.8 PSI...
56 sounds too high based on the AC PRO Gauge... But if you compare to the BLUE CHART ABOVE, it seems to agree... The blue chart says 50-55 PSI is ok. Let me know what you think.
Either way, when it is 95 degrees the output temperature is within range if it falls between 54ish and 75ish degrees.. 75 degree is not much cooling! But they say it is normal.

 

actually the AC PRO gauge is pretty close on the bottom end. The gauge shows 25 psi is minimum filled green section. And the Chart shows about 19-ish psi at 68 degrees.

 

It depends on the humidity level too! The book says at 70% humidity it will give you 63.5 degree output when external temp is 86. I know my TL gets much colder than that when the air is on recirculate vs using fresh (hot) air from outside the car.

 

Ya something is funky with that chart. 63 at the vent or at the delivery exit , does not sound very cold.. But then again, my AC doesnt always get real cold , unless I leave it on a long time while driving... And I just had it professionally filled. But sometimes it DOES seem colder.. You know, since pressure increases with temperature, does that mean it should do a better job at cooling on hotter days? So, that would indicated a "non-linear" degree of cooling. So in that sense, the chart may not be 100%, but only a guideline. Still, I think a safe way of measuring the low side pressure is to take a reading on a Hot and humid day. Like, use a barometer to actually measure the Humidity because it is hard measure it by seat of the pants. What we feel is so influenced by temperature it is easy to misjudge it.

 

I am still learning how the AC system works, and I understand there is a difference in the low side pressure when compared to the resting pressure vs. the pressure value after the system has been running for 10 minutes or more. When the system is at rest and has not been running, then the pressure should be at or near the Ambient air temperature. But as the system warms up and begins to operate and the high pressure side increases, then the low side decreases in pressure. So I think the Picture ABOVE is the pressure after the system has been running and is warmed up and operating ..

However, the Pressure table BELOW is static pressure or at Resting state when the system has not warmed up and is not operating.


THis video explain a bit of that.. But you have to pay close attention to his fast talking. But he is not the only guy on video saying the same thing about static pressure

 

today I checked the pressure, 85F with 72% humidity and it was around 34 psi on the low side after the car was running for a few minutes, last time I had the system recharged was 2019 so it might be on the lower side; according to the chart it should be closer to 40PSI so I might need a top off...

 

Could be.
But I also noticed something about the static pressure chart. Taking a measurement when the ambient temp is 80 or higher is really hard to do on the Low Side of the system while using a cheap pressure gauge like a ACPRO or any others like that because those pressure gauges top out at 60psi. (can we guess where 70 is?) And if the low side is equal to, or higher than the ambient temp then it could go off the scale on the gauge. On the ACpro, it appears to go crazy after 60psi. I question the accuracy after 60psi in the red section because it says 150psi at the max, but if you look at the distance between 10, 20 , 30 ,40 , 50 and 60, it only goes up 10psi per increment. And between 60 and 150 psi it APPEARS to be only about 2 increments, which would be around 80psi, not 150. So I don't understand that. It doesnt look right. Besides, even if it is correct, it would be too hard to estimate where is 95psi? I mean, you need a better gauge to read the higher pressures. And ambient temps while the system has not been running will be very high in the summer and likely off the scale. You would have to take a reading in the morning when the temp is still around 75.. Not 90+. Or get a better gauge that has more detail and goes higher than 60

 

1 more thing about adding refrigerant. Unless the Gauge adapter line is purged, then you could be adding normal air into the system.
The best method is to put the can on the hose and purge the air out of the hose until you see R143a come out.
It's not much air in the hose, but if you do it over and over , it may not be good. It could bring in moisture.
The big professional gages have a purge valve. I am not sure if you can purge an ACPRO type line that comes attached to the can.
You would have to pressureize the line and then open the valve somehow, let it push our R134a, before you attach the gauge to the Car..
Either way, good idea to wear safety goggles.

 

I found this chart for taking pressure readings after the system is Warm and been running. This should match the Black and White Diagram above. But this does not account for humidity.
Comparing this to the black and white chart above, it looks to be a high estimate. So, I would not go over what it says below