Static A/C pressure.
06-06-2011, 01:51 PM
#1
Drifting
Thread Starter
Static A/C pressure.
Anyone know what it should be...?
Low side pressure with the compressor/system having not been operated for a day or so, refrigerant evenly distributed throughout the system?
'88 Carrera.
Mine reads 65PSI.
Low side pressure with the compressor/system having not been operated for a day or so, refrigerant evenly distributed throughout the system?
'88 Carrera.
Mine reads 65PSI.
06-06-2011, 03:00 PM
#2
I haddah Google dat
Rennlist Member
Rennlist Member
I would say that sounds about right, but you know it's dependent on temperature and that the "money number" is while the engine is running around 80F ambient.
06-18-2011, 07:48 AM
#3
Intermediate
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From an A/C website:
Each refrigerant has it's own static pressure at every corresponding degree in temperature. The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low. This is because static pressures shown on a temperature chart would show inadequate pressure for the presence of any liquid refrigerant.
Each refrigerant has it's own static pressure at every corresponding degree in temperature. The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low. This is because static pressures shown on a temperature chart would show inadequate pressure for the presence of any liquid refrigerant.
06-18-2011, 03:25 PM
#4
Drifting
Thread Starter
From an A/C website:
Each refrigerant has it's own static pressure at every corresponding degree in temperature. The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low. This is because static pressures shown on a temperature chart would show inadequate pressure for the presence of any liquid refrigerant.
Each refrigerant has it's own static pressure at every corresponding degree in temperature. The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low. This is because static pressures shown on a temperature chart would show inadequate pressure for the presence of any liquid refrigerant.
Or...
We can assume that the system has some amount of refrigerant in a gaseous state..that can be "converted" to a liquid once compressor is again enabled.
06-18-2011, 03:55 PM
#5
Race Car
I think that chart is made with a known amount of freon in a known volume container. Like one pound of freon in a one cubic foot of container...or somesuch. Then pressure is measured across a range of temps. It's very linear, temp/pressure that is. Your high side pressures can be roughly assumed to be the temperature of you condensor, your low side pressures are roughly your evap temp(and air temp in the dash). Some gauges have a temperature scale right alongside your pressure scales.
Static pressure has little diagnostic value.
Static pressure has little diagnostic value.
06-19-2011, 12:26 AM
#6
Drifting
Thread Starter
"....Static pressure has little diagnostic value..."
How, why so...?
Static pressure reading tells me that the system is basically charged, with static pressure to low there is simply no need for further "diagnostics", troubleshooting.
How, why so...?
Static pressure reading tells me that the system is basically charged, with static pressure to low there is simply no need for further "diagnostics", troubleshooting.
06-19-2011, 08:08 AM
#7
Rennlist Member
Static, meaning "just sitting there"?
Am new to AC but have been running through my system, as of late,..with some great indtructions/guidance from other RL's. Have all the charts at hand and have gone through one charge already. My system is virgin R-12...
A few weeks ago, we engaged an R12 charge, since she was not blowing cold air....it had been a few years since the last charge so I knew it was time. I've been working with an old school guy and he's been very helpful in teaching me his ways (along with interface with the fellow RL's who have helped in SO many ways). One thing he did do was to check this "static" pressure to determine if it had any freon IN IT .....it showed around 9 PSI so we were good to go for top off. Beyond this, all was done "dynamically" (noting ambient temps /charts, spec'd RPMs, pressures, vent temps, HEALTHY blowers blowing on BOTH condensors).....
Our initial reading (static) told us only that we had a charge (to degree, but not spec) and that the system was NOT EMPTY of freon (certainly diagnostic only, as we had not yet looked at any spec measurements at 2K RPMs at THAT point).
Maybe I'm a bit twisted on my verbiage...but "static" would tell me little (other than what's noted above). ....dynamic's where it's at (although I don't mind seeing what's up at "idle", but that's about as "static" as we got.......).
AGAIN, remember that I'm new to this !!!!!!!
BEST!
Doyle
Am new to AC but have been running through my system, as of late,..with some great indtructions/guidance from other RL's. Have all the charts at hand and have gone through one charge already. My system is virgin R-12...
A few weeks ago, we engaged an R12 charge, since she was not blowing cold air....it had been a few years since the last charge so I knew it was time. I've been working with an old school guy and he's been very helpful in teaching me his ways (along with interface with the fellow RL's who have helped in SO many ways). One thing he did do was to check this "static" pressure to determine if it had any freon IN IT .....it showed around 9 PSI so we were good to go for top off. Beyond this, all was done "dynamically" (noting ambient temps /charts, spec'd RPMs, pressures, vent temps, HEALTHY blowers blowing on BOTH condensors).....
Our initial reading (static) told us only that we had a charge (to degree, but not spec) and that the system was NOT EMPTY of freon (certainly diagnostic only, as we had not yet looked at any spec measurements at 2K RPMs at THAT point).
Maybe I'm a bit twisted on my verbiage...but "static" would tell me little (other than what's noted above). ....dynamic's where it's at (although I don't mind seeing what's up at "idle", but that's about as "static" as we got.......).
AGAIN, remember that I'm new to this !!!!!!!
BEST!
Doyle
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06-20-2011, 12:01 AM
#8
Drifting
Thread Starter
To my mind if I found the static pressure(***) to be near or below the active/working suction side pressure (30-40PSI depending on OAT comes to mind) I would have no doubt that the refrigerant pressure was too low.
*** Yes, "just sitting there", and not having been operated for at least 24 hours.
*** Yes, "just sitting there", and not having been operated for at least 24 hours.
