I'm getting a 15 psi differance in my readings on the low side. Goes up to 45 psi when the compressor clicks on and it slowly drops to 30 psi when it clicks off. Which reading do you go by? thanks.
A/C low port pressure reading question...
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when the compressor is on. sound like normal operation
both. the pressure fluctuates
and based on that info alone I would say its working ok... but really need to know what the high side is doing as well and vent temps.
what problems are you having?
and based on that info alone I would say its working ok... but really need to know what the high side is doing as well and vent temps.
what problems are you having?
You read the low when it is 'ON'. - the high reading.
Think about it - why would an 'OFF' reading be valid??
This is tied into ambient temperatures, outlet temps., and the high side reading.
Think about it - why would an 'OFF' reading be valid??
This is tied into ambient temperatures, outlet temps., and the high side reading.
Thanks for the info!... I just hooked up a gauge and was curious if this reading was normal. Yes, it is blowing cold and seems to work fine. Truck is 9 yrs old and the A/C has never been serviced. It was only 61 degrees outside when I checked it though.
Originally Posted By: Texan4Life
and based on that info alone I would say its working ok... but really need to know what the high side is doing
X2. I can't begin to diagnose it w/o a high side reading and knowing the outside temp
and based on that info alone I would say its working ok... but really need to know what the high side is doing
X2. I can't begin to diagnose it w/o a high side reading and knowing the outside temp
JHZR2
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Originally Posted By: Blaze
Thanks for the info!... I just hooked up a gauge and was curious if this reading was normal. Yes, it is blowing cold and seems to work fine. Truck is 9 yrs old and the A/C has never been serviced. It was only 61 degrees outside when I checked it though.
If it is only 61 degrees, the evaporator may get too cold, so the system sill cycle more as there isnt a lot of enthaly moving through.
if it was 95 the compressor may not cycle much at all.
When it is not cycling, the pressure will rise as more and more refrigerant expands and vaporizes.
Thanks for the info!... I just hooked up a gauge and was curious if this reading was normal. Yes, it is blowing cold and seems to work fine. Truck is 9 yrs old and the A/C has never been serviced. It was only 61 degrees outside when I checked it though.
If it is only 61 degrees, the evaporator may get too cold, so the system sill cycle more as there isnt a lot of enthaly moving through.
if it was 95 the compressor may not cycle much at all.
When it is not cycling, the pressure will rise as more and more refrigerant expands and vaporizes.
absolutely. Im currently in my heating/ac class in the automotive technology program im taking, and can verify everything said here is true.
You should go by the higher reading your getting, and you should most definitely have a gauge on your high side at the same time. The low side reading you have is a good reading, and your system is most likely ok since your a/c is blowing cold. But when diagnosing an A/C problem, that low side reading is completely useless without the high side reading to go along with it.
(if your orifice tube was clogged, you could have a lower then normal low side reading, and a high side reading so high its about to blow, and you'd never know it. you'd just keep pumping refrigerant in it til that low side reading was ok)
and theres no way you can accurately test an A/C if its only 61 degrees Fahrenheit outside..
You should go by the higher reading your getting, and you should most definitely have a gauge on your high side at the same time. The low side reading you have is a good reading, and your system is most likely ok since your a/c is blowing cold. But when diagnosing an A/C problem, that low side reading is completely useless without the high side reading to go along with it.
(if your orifice tube was clogged, you could have a lower then normal low side reading, and a high side reading so high its about to blow, and you'd never know it. you'd just keep pumping refrigerant in it til that low side reading was ok)
and theres no way you can accurately test an A/C if its only 61 degrees Fahrenheit outside..
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I like to know the static pressure when I have no high side gauges to work with. This gives you an idea on how much is in the system based on temp and combined with low side readings you have a better idea. As 5 psi can make a huge difference on these cars that only contain 2lbs of R134a.
Static rest pressure is a very useful tool.
That is when the car has been sitting and is dead cold [preferably out of the sun, too]. The high and low sides are equal, then, and not affected by engine or running temperature..
It should be approx the ambient/outside air temps.
Online charts will tell you exactly the minor differences.
And remember, dead cold or forget it.
That is when the car has been sitting and is dead cold [preferably out of the sun, too]. The high and low sides are equal, then, and not affected by engine or running temperature..
It should be approx the ambient/outside air temps.
Online charts will tell you exactly the minor differences.
And remember, dead cold or forget it.
Originally Posted By: 97 GTP
I like to know the static pressure when I have no high side gauges to work with. This gives you an idea on how much is in the system based on temp and combined with low side readings you have a better idea.
that's not entirely true. a static pressure reading- when the system is off and at equilibrium temperature throughout- only tells you if you have liquid refrigerant in the system. You cannot tell how many lbs of refrigerant there is by a static pressure reading, the only thing it can do is tell if you are really low.
I like to know the static pressure when I have no high side gauges to work with. This gives you an idea on how much is in the system based on temp and combined with low side readings you have a better idea.
that's not entirely true. a static pressure reading- when the system is off and at equilibrium temperature throughout- only tells you if you have liquid refrigerant in the system. You cannot tell how many lbs of refrigerant there is by a static pressure reading, the only thing it can do is tell if you are really low.
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