A/C pressure readings
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New User
Joined: Feb 2003
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From: FL
A/C pressure readings
Does anyone know what the pressure readings should be? I have a 2000, f340, v10, crewcab. I need to put more r134 in it, i think, but dont know what it should be. The readings now are low 30-36, high 145-148, the temp comming out of the vents is 42 d. My wife is always complaining that its not cold enough... 
I sure could use some help b4 my ears get colliflored.
Thanks
Ray
I sure could use some help b4 my ears get colliflored.Thanks
Ray
Posting Guru
Joined: Nov 2003
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From: Near DC
Have you looked into the heater control valve?
Keeps the hot water away from the core, the same core that I THINK the a/c flows past.
Or something like that... They say it makes the a/c colder.
I'm going to order it in a week or so, before it gets real hot around here.
Keeps the hot water away from the core, the same core that I THINK the a/c flows past.
Or something like that... They say it makes the a/c colder.
I'm going to order it in a week or so, before it gets real hot around here.
Elder User
Joined: Jun 2001
Posts: 775
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From: Northern Va
If you have a good gauge, on the gauge there should be some numbers usually on the inner portion of the dial. If you look, sometimes there are several rings that are marked with "R-134A", "R-12" etc. They are on both the high and low sides.
Look at the "R-134" ring and the number on that ring should be right around the vent temp on the low side. If I remember correctly, R-12 systems should be around 35psi at 35/40 deg vent temp. The high side numbers should equate to the outside temp...roughly..
Look at the "R-134" ring and the number on that ring should be right around the vent temp on the low side. If I remember correctly, R-12 systems should be around 35psi at 35/40 deg vent temp. The high side numbers should equate to the outside temp...roughly..
Elder User
Joined: Dec 2004
Posts: 819
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From: Putnam Valley, New York
A/c
Originally Posted by rmaxwell
Does anyone know what the pressure readings should be? I have a 2000, f340, v10, crewcab. I need to put more r134 in it, i think, but dont know what it should be. The readings now are low 30-36, high 145-148, the temp comming out of the vents is 42 d. My wife is always complaining that its not cold enough... I sure could use some help b4 my ears get colliflored.
Thanks
Ray
I sure could use some help b4 my ears get colliflored.Thanks
Ray
Hi Ray,
Your low side is slightly higher than it should be. Depending on the outside temp & humidity, and the blower speed, the low side should go down to as low as 22 and then cut the compressor off, and when the pressure rises to about 40, the compressor should cycle back on. High side pressure is again dependent on temp, humidity, and blower speed. On an average 70-75 degree not too humid day, with the blower on #3 speed, your low side should cycle as described above and the high side should be about 150-175. This should provide you with an outlet temp of about 40 degrees if everything is OK. Hold the RPM's at about 1500, and the compressor should cycle about every 30 seconds. If it is short cycling, then it's probably low on refrigerant, but 42 degrees sounds decent to me. If you do add gas and the temp goes up, then you are most likely overcharged.
Last edited by Rongold; Jun 2, 2005 at 07:24 PM.
