help with freon charge

[greenleg88]

can someone direct me on a proper freon charge.

 

i went to a mechanic he said to just add a can.

 

so i bought this can and it came with this gauge that has low, full, alert, and danger all along the gauge.

 

 

what is the psi that the low pressure valve should be reading? im trying to do a charge. cept the gauge is saying its in the danger zone and im not sure whether or not to continue. i JUST read that people were saying to ignore the colors.. and just look at hte numbers.. and that youre supposed to take the temperature... and add 23 and thats the psi to fill to... im really not sure..

 

also. i read on the back of the can, depending on the temperature of the air around the AC the low pressure range is different.

 

what should i fill to?

 

thanks!

[screwbaru2]

Is this the car where you got this good advise?:

The next step is to take it to a professional, because you need to throw a set of gauges on it to see what the pressures are. Sure you can just throw money at it and start adding refridgerant, but it wont solve the issue of where the refridgerant went to begin with.

 

I dont remeber if the cooling fans will come on if the system is low on pressure.

 

 

nipper

 

I'd take it if I were you.

[idosubaru]

this isn't as simple as a lot of other automotive things. i would want to know why you're recharging it and if you tracked down exactly why the a/c isn't working or why it was low to begin with. and if it's low did you fix the leak first?

 

maybe someone with siginficant a/c experience will pipe up but if that doesn't happen i'd suggest doing a lot of reading about a/c stuff on the internet and learning how it works. that helped me a good deal in the past.

 

i'm personally not acquainted enough to tell you to ignore charging "into the red".

 

from memory, the EJ's that i've recharged took approximately two cans of charge when completely empty. but it sounds like yours may have had some remaining charge and you obviously aren't drawing a vacuum on it?

[greenleg88]

this isn't as simple as a lot of other automotive things. i would want to know why you're recharging it and if you tracked down exactly why the a/c isn't working or why it was low to begin with. and if it's low did you fix the leak first?

 

maybe someone with siginficant a/c experience will pipe up but if that doesn't happen i'd suggest doing a lot of reading about a/c stuff on the internet and learning how it works. that helped me a good deal in the past.

 

i'm personally not acquainted enough to tell you to ignore charging "into the red".

 

from memory, the EJ's that i've recharged took approximately two cans of charge when completely empty. but it sounds like yours may have had some remaining charge and you obviously aren't drawing a vacuum on it?

 

hokay so, i talked to this awesome mechanic. he said it was possible the car had just run out of freon from being 11 years old. and being used a lot since its in a hot area. he recommended i just try a can and if that didnt work bring it in. he said that if the car was just low on freon that the can would work. but if it was pretty much empty than it might not work because there woudl be so much air in the system.

[edrach]

Having just "topped up" the charge in my '97 I found the pressures to be 23psi on the low side and 210psi on the high side using R134a when it was working normally. Yes, you need guages to read the pressures. Both pressures are important: the low side tells you there is enough refrigerant in the system and the high side tells you that there isn't too much.

 

Rule of thumb is that the ratio of high side to low side pressures should be around 10:1 and the maximum pressure on the high side should be around or below 250psi.

[greenleg88]

what was the temperature outside?

[idosubaru]

if the car was "empty" it can take significantly more than one can to fill. the last one i charged i want to say took *roughly* two cans...but that's from memory. pretty sure just one won't cut it.

 

what i would have done is pressed in the schrader valve to see if the system is pressurized at all or not before you charged the first time.

 

if it's empty and you have a leak that bad, it's not going to stay in long.

 

if you determine another can is needed, try some with the "stop leak" stuff in it. i'm not a big fan of those kinds of "fixes" but i've seen it work and probably most successfully/often in A/C systems.

[edrach]

what was the temperature outside?

75 degrees F.

 

I'm not sure of how much that has to do with it since the underhood engine temp is around 190 degrees F. Of course the cooling heat exchanger is in front of the radiator and is seeing ambient air, and I'm more concerned with that 10:1 ratio, the high side pressure, and the fact that the compressor cycles on an off during operation after it's all done.

[McDave]

if you determine another can is needed, try some with the "stop leak" stuff in it. i'm not a big fan of those kinds of "fixes" but i've seen it work and probably most successfully/often in A/C systems.

 

DO NOT use A/C stop leak!!!! When it still doesn't work and he has to take it to a pro anyway, that crap can, and will stop up the shop's recycling equipment. Really good way to piss off your mechanic!

 

/soapbox