How much refrigerant do I need?

[AlanS]

So, it's summer...My A/C in my 95- 850 NA could be colder. I replaced the evaporator and drier last year, so I know that the system is o.k.. How do I know that I have enough coolant in the system? I see that I can buy a can at the local auto parts store, but how do you know if you put 'too' much in?

[andy86+volvo]

I just recharged mine a couple weeks ago and bought the can with the gauge and the hose attached. It was the sub zero I believe. It's got a polar bear on the can if that helps. I had never done it before and was verry nervous. But the instructions on the can are very clear and easy to follow. But if memory serves me when the compressor is running your PSI reading should be between 35 and 40 so it depends on that. Hope this helps I think I need to add some more to mine though it's not quite cold enough and I added the whole can. It was 16 ounces so I'd say starting off with one pound would be a good starting point and I highly recommend the gauge as well because overcharging it could be hazardous in more ways than one good luck hope this helps

[Ozark Lee]

You need to get a pressure gauge on the system and even then there is no definitive answer to your question since the pressures will vary with ambient temperature. As a rule of thumb you should see in the mid 30s PSI range (Compressor Running) on a properly charged system and the compressor should not cycle on and off.

...Lee

[JRL]

These cars take 1.65 lbs from dead empty, you can figure out how much you think you may need from that
An full charge from dead empty is approx. two 12 oz. cans of R 134

[bobice]

IN the gauge I bought, there is a dial that point to the Ambient Temperature, the pressure should be between the upper and lower limits of the red lines. The pressure depends on temperature.

[andy86+volvo]

You need to get a pressure gauge on the system and even then there is no definitive answer to your question since the pressures will vary with ambient temperature. As a rule of thumb you should see in the mid 30s PSI range (Compressor Running) on a properly charged system and the compressor should not cycle on and off.

...Lee

Hey lee what does it mean if the compressor does cycle on and off ? That is what mine is doing and it's still not COLD just cool but is deffinetly a drastic improvement from before. I think I need another can what are your thoughts?

[da7]

hi andy86+volvo: the air compressor usually cycles off when the pressure in the low end of the compressor drops below 18-20 psi to protect the compressor, as low pressure usually means low in freon and that usually means low in lubricant (or no lubricant/freon), but I think there is also a high pressure cut off switch which protects the compressor from trying to compress liquid ie. when there's too much freon (this is usually rarer) but is possible when the system is overcharged... but when the compressor is trying to compress liquid you will hear a knocking sound as the liquid freon can't be compressed

so based on a rough guess, I'd say you are low on freon, but it's recommended you have a pressure gauge while topping up, so that you have the ideal pressure, you should be able to find a chart that dictates the right pressure at the low end depending on the ambient temperature, and roughly from memory is about 35-38 psi on a 35 degrees day, and lower on cooler days down to minimum approx 25psi if it's about 28 degrees celcius I think... you should be able to google it..

[andy86+volvo]

Thanks that is kinda what I suspected and thanks for the info

[da7]

no problems! good luck with it!

[JRL]

Thanks that is kinda what I suspected and thanks for the info

Sounds like one can for you wil be just what you need (12 oz can)