A/C pressure problem, help me figure this out!!!
02-15-2010, 03:11 PM
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A/C pressure problem, help me figure this out!!! Ok so I am new to working on A/C, never had any A/C problems ever in my life so, from what I've been reading online and trying to get familiar with how the system works I am still wanting peoples opinions on what they think, if they have ever had a similar situation etc...
Basically, my A/C was just blowing plain air so I decided to refill it, which I've done in the past no big deal, well, at first I thought my pressure guage was broken because it wasn't going higher than 17 psi ??
Which if you don't know, that is only half way full and basically is telling you to refill it. I used a couple cans of synthetic leak sealers and the pressure still would not go any higher than 17 psi. At one point it DID go up to the green and blue line border which means it was almost full, but then my fans clicked on and it went back down to 15 psi...which from there after tryin to fill it again it wouldn't go higher than 17 psi. 
What controls the pressure? What do you think my problem is? I have been reading online that the Orfice Tube controls the flow and pressure, how often do these need to be changed, could that be my problem? My car is a 98 with 130k miles, AKA problem city. SO PLEASE SHOOT ME SOME ADVICE, AND TRY TO BE AS DETAILED AS POSSIBLE! =) Thanks everyone!
Basically, my A/C was just blowing plain air so I decided to refill it, which I've done in the past no big deal, well, at first I thought my pressure guage was broken because it wasn't going higher than 17 psi ??
Which if you don't know, that is only half way full and basically is telling you to refill it. I used a couple cans of synthetic leak sealers and the pressure still would not go any higher than 17 psi. At one point it DID go up to the green and blue line border which means it was almost full, but then my fans clicked on and it went back down to 15 psi...which from there after tryin to fill it again it wouldn't go higher than 17 psi. What controls the pressure? What do you think my problem is? I have been reading online that the Orfice Tube controls the flow and pressure, how often do these need to be changed, could that be my problem? My car is a 98 with 130k miles, AKA problem city. SO PLEASE SHOOT ME SOME ADVICE, AND TRY TO BE AS DETAILED AS POSSIBLE! =) Thanks everyone!
02-15-2010, 05:18 PM
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Pressure is controlled by a couple of things, one of which is ambient temperature.
A prominent myth is that you can correctly charge an A/C system with nothing but a pressure gauge. A/C systems are correctly charged by the volume of refrigerant you put in, not by the pressure. This is so, particularly in an air cooled system, because of the relationship that ambient temperature has with system pressure on the high pressure side.
Also, the pressure measured on the high pressure side has absolutely nothing to do with pressure on the low pressure side, assuming the system is on. If off, then they tend to equalize over time.
Having any air/non-condensible gas in the sytem will throw the high pressure readings WAY out, which is why a reputable shop will first evacuate (put under a vacuum) a system prior to charging, and then put in the number of ounces of refrigerant the manufacturer has called for. This also has the added benefit of removing any moisture from the system which will also cause headaches.
The first question I'd have in your situation is, are you certain that the compressor was acutally coming on?
A prominent myth is that you can correctly charge an A/C system with nothing but a pressure gauge. A/C systems are correctly charged by the volume of refrigerant you put in, not by the pressure. This is so, particularly in an air cooled system, because of the relationship that ambient temperature has with system pressure on the high pressure side.
Also, the pressure measured on the high pressure side has absolutely nothing to do with pressure on the low pressure side, assuming the system is on. If off, then they tend to equalize over time.
Having any air/non-condensible gas in the sytem will throw the high pressure readings WAY out, which is why a reputable shop will first evacuate (put under a vacuum) a system prior to charging, and then put in the number of ounces of refrigerant the manufacturer has called for. This also has the added benefit of removing any moisture from the system which will also cause headaches.
The first question I'd have in your situation is, are you certain that the compressor was acutally coming on?
