When is freon pressure gauge accurate?

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Old 03-29-09, 10:43 AM
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When is freon pressure gauge accurate?

I was wondering when the freon pressure gauge is accurate. Is it accurate when the compressor is running, or when the compressor is off?
 
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Old 03-29-09, 10:48 AM
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Both are accurate. When it's off it's the evaporative pressure, when it's running, it's either the low side or high side pressure depending on where it's connected. At the risk of over simplifying, it's got just the right amount of freon in it when it's blowing cold air. Too little or too much, and it won't blow cold.
 
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Old 03-29-09, 10:52 AM
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Thank you very much. I've been stuggeling for the past year (during the warm season) with my high pressure hose. The factory hose went bad and I replaced it with a aftermarket from Autozone. The aftermarket lasted for about 7 months and Autozone honored it under warranty and gave me the hose, freon and oil that was lost. Now I have put the replacement on and it seem that I am still loosing pressure but its not coming from any of my connection or the high pressure hose at all. Looks like I'm finally going to have to break down and take it somewhere. More than likely its leaking in the dash or firewall somewhere. Now I'm begining to wonder if the aftermarket was ever defective after all. Thanks for the help..
 
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Old 03-29-09, 10:59 AM
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Zombie..just wondering when you had the problem, did you just put a new hose on and fill it? Thats not the way it works...
 
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Old 03-29-09, 11:09 AM
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the pressure on the high side is never going to be higher than when the compressor is running so that is the pressure you need to be concerning with in this situation.
 
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Old 03-29-09, 11:28 AM
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Yes, pretty much took the defective hose off, put the new one on, added one can of freon using the low side port, added the oil, and then two more cans of freon. That's the way they told me to do it.
 
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Old 03-29-09, 11:31 AM
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Ouch..I'm no mechanic..but I'm pretty sure thats not right. Just like a home system I think, you have to seal the system, draw a vacuum then put the proper amount of oil/freon in.

I might be wrong, but I don't think so.

Adding to a leaky system is one thing, but once you open it up, its completely different.
 
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Old 03-29-09, 11:48 AM
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gunguy is correct. Once the system is open, you have introduced moisture and air. You need to remove that and you do that by vacuuming the system. If you do not do that, the system may work BUT it is not as efficient (doesn;t work as well) as a properly charged system will.
 
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Old 03-29-09, 12:28 PM
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Hmm, seems like I do vaguely remember my father telling me last year to take it to his house and let him do that. I'm not sure why I never went. I guess because the guys that the parts place told me I didn't have to. Owell, I guess there goes another $40 in freon and oil. Thanks yall.
 
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Old 03-30-09, 05:09 AM
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I gotta wonder at this point how much oil you have added over the course of repairs. Too much oil causes issues as well. If you take it someplace for diagnosis, be sure to tell them everything that has been done including amounts. Unfortunately, the only sure way to determine how much oil or refrigerant is in a system is to remove it and measure the volume...easy to do with refrigerant...not easy with the oil.
 
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