a/c recharge issue

[spools420a]

Hi zilvians,My a/c in my s13 was slowly leaking out of the shrader valve on the high side port so today I decided to replace the Schrader valve and recharge the system,the guy at autozone said it will take two and a half cans from a empty a/c unit to fill.I then turned the car on and put the a/c on high but could not get the a/c compressor to engage unless it was at medium or lower fan setting so I left it on medium and filled it up,but I cant get the a/c to engage on high setting now?it was fine before so I assume its eather too charged or not enough charge in the system I think my guage is wrong as its at 35 psi in the blue and should be good(this was after I decided to leak off eccessive pressure.would too much or too little recharge cause this issue?which one?thanks.


also what psi should the low and high ports be at?

[battery1882]

Hi zilvians,My a/c in my s13 was slowly leaking out of the shrader valve on the high side port so today I decided to replace the Schrader valve and recharge the system,the guy at autozone said it will take two and a half cans from a empty a/c unit to fill.I then turned the car on and put the a/c on high but could not get the a/c compressor to engage unless it was at medium or lower fan setting so I left it on medium and filled it up,but I cant get the a/c to engage on high setting now?it was fine before so I assume its eather too charged or not enough charge in the system I think my guage is wrong as its at 35 psi in the blue and should be good(this was after I decided to leak off eccessive pressure.would too much or too little recharge cause this issue?which one?thanks.

Either too high or too low could cause AC to not function correctly. Pressure sensor would stop compressor.

[racepar1]

You should not charge an empty system with the janky ass cans they sell at vatozone or similar auto parts shithouses. Those are made to TOP OFF a partially charged system. Your A/C system will not function properly with air in it, it needs to be put under vacuum before it is charged. Those fucking stupid cans should be illegal. Go to a shop, get it done right.

[spools420a]

You should not charge an empty system with the janky ass cans they sell at vatozone or similar auto parts shithouses. Those are made to TOP OFF a partially charged system. Your A/C system will not function properly with air in it, it needs to be put under vacuum before it is charged. Those fucking stupid cans should be illegal. Go to a shop, get it done right.
true but my a/c is blowing as cold as 45 degrees at nighttime so I don't see the logic of spending big bucks if the air is coming out nice and cold and you put the correct amount of oil in the system,That is the goal to have ice cold air non the less but I will certainly do this in the near future.I also read that the outside air temp has dramatic effects on what psi the recharge should be at for instance if its 65 degrees outside the recharge should be at around 23-65 psi on low and 135-155psi on high side,if its 110 degrees outside the system should be closer to 50-55 psi and 340 psi what a dramatic change

[yzrider450f]

true but my a/c is blowing as cold as 45 degrees at nighttime so I don't see the logic of spending big bucks if the air is coming out nice and cold and you put the correct amount of oil in the system,That is the goal to have ice cold air non the less but I will certainly do this in the near future.I also read that the outside air temp has dramatic effects on what psi the recharge should be at for instance if its 65 degrees outside the recharge should be at around 23-65 psi on low and 135-155psi on high side,if its 110 degrees outside the system should be closer to 50-55 psi and 340 psi what a dramatic change

Yeah, you cant just use the cans to refill an empty system. You need to remove all the air to replace it with the R134 with a special tool.

[racepar1]

true but my a/c is blowing as cold as 45 degrees at nighttime so I don't see the logic of spending big bucks if the air is coming out nice and cold and you put the correct amount of oil in the system,That is the goal to have ice cold air non the less but I will certainly do this in the near future.I also read that the outside air temp has dramatic effects on what psi the recharge should be at for instance if its 65 degrees outside the recharge should be at around 23-65 psi on low and 135-155psi on high side,if its 110 degrees outside the system should be closer to 50-55 psi and 340 psi what a dramatic change

First off, it'll cost less than $100 to go to a shop and have them charge the system. That's NOT "big bucks". Most places will charge $40-$50 labor +refrigerant. A full charge in a 240sx is about 1.6lbs, so even if they charge you $20/lb (which is a LOT) at 2 lbs you're still under $100.

Second, you're beating your head against a wall trying to figure out if the system is over or under charged and your A/C doesn't work anywhere near correctly and you don't see a point to spending some chump change on getting it charged properly? That makes no sense.

Air in the system will fuck with the pressures dramatically. To me it sounds like that is your primary problem. As for it only working on certain blower speeds, that also makes no sense. The speed of the blower should have absolutely no effect on whether or not the compressor turns on initially. If the system isn't charged properly the blower speed could effect the system pressures to the point where it will shut off randomly. It could also cause the evaporator to freeze at certain blower speeds, which will also shut the system down. It absolutely should not cause the compressor to refuse to turn on though.

As for what the pressures should be, that's honestly a more difficult question to answer than you think. As you know, pressures depend on temperature. Also, a system that was ORIGINALLY R12 and was CONVERTED to R134 will NOT operate at the same high side pressure as was originally intended OR at the same pressure as an OE R134 system. The low side, however, is pretty consistent, usually 35-45psi.

[burnsauto]

exactly. I recover and recharge them constantly, and I would never use one of those parts store rip off systems.


A completely empty system needs to be put on a vacuum, leak tested (basically monitor the level of vacuum in the system and see if it drops), oiled if need be, and recharged to the correct amount of refrigerant.


If A/C is important enough to you that you're trying to fix it, go have a qualified tech do it for you. The equipment that you'd need to do this correctly can cost 1000's of dollars. You can have peace of mind knowing it was done correctly, and have someone to go to if you're having any problems. Good luck :)

[boosted23]

Your ac system typically only needs 50 psi to get tje compressor to turn on. You gave it that by using tje cans. The system needs to be put onto a vacuum and have a proper charge. Your ac works at night cause the refrigerant doesn't have to work hard to remove moisture and create cold air. In tje day it works 100% more. The air and refrigerant in your system is connaught cause you more issues if you don't just get it properly evacuated and recharge. I'm a 12yr nissan tech so what do I know right?

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[red92ka]

First mistake was using that shit in cans to recharge your a/c.