johnceggleston Posted May 16, 2012 Share Posted May 16, 2012 (edited) i bopught the car at thanksgiving and the AC did not work. no big deal, it was winter. last week i started to fix it. based on gary's thread, i replaced the o-rings at the compressor and re-charged the system. i got the pressure in the green, but it still did not cool. the compressor clutch was bad. i bought one for $70, shipped, from car-part.com. i replaced the compressor and re-charged the system again. yeah, now it works. i charged the system with one 12 oz. bottle of r134 ( i later added one 3 oz. bottle of leak stop and indicator) and the pressure only barely comes up to the green on the gauge. just under 20 psi. i'm undecided about adding more since it is cooling (60* air in the 68 degree weather), AND i'm not sure i have eliminated all the leaks. r134 isn't terribly expensive but it isn't free either. does this ''low pressure '' situation suggest any thing other than it needs more r134? the other car: when i first charged the H6 i used an 18 oz bottle and had some left over and i decided to check my 97 GT w/ ej22. i have had the car for several years and it has always done the job, but i had the extra r134 and this new gauge. it was in the green but a little low for the outside temp. so i added some, no problem. but when the compressor cycled off, the pressure on the system jumped up almost to the red. as soon as the compressor came back on it drop to normal for the conditions. HUH? also the compressor seems to cycle on and off much more quickly, more often, than my other cars? HUH? as the pressure approaches the red, the compressor comes back on. (PS: this is with the doors and windows open, so there isn't mucjh chance that the t-stat? or what ever thinks the car inside is already cool.??) any experienced AC gurus out there with insights? thanks, john Edited May 16, 2012 by johnceggleston Link to comment Share on other sites More sharing options...
Rooster2 Posted May 16, 2012 Share Posted May 16, 2012 One 12 oz can of R134 is not enough. You will need to have about 2 and a half cans in the system to fill it up. The hose gauge on a 12 oz can have a reputation of not being very accurate. IMO, you can add 134, and have the gauge register just slightly in the red zone on the gauge, and still be okay. If you add too much R134 to over pressure the system, the compressor will not turn on, so there is built in protection against damaging the system. Don't add any more of the stop leak into the system. I learned the hard way that adding the stop leak is a good way to permanently plug up the flow of 134 through the narrow tubing of the condenser and evaporator. When that happens, you are back to not having the A/C work again. On your other car, where you added some 134, you may have added just a little too much 134. When the compressor starts cycling on and off quickly, that is an indication that the system is either too low or too high on 134. Bleed some 134 off, and see if the extreme cycling calms down. You don't say anything about having a vacuum drawn on your A/C system, after having the system "opened" to install the new O rings. This should have been done to draw the atmospheric air and moisture out of the system. Link to comment Share on other sites More sharing options...
nipper Posted May 16, 2012 Share Posted May 16, 2012 Some of these hyad bad AC hoses that were porus, so keep that in mind too. Link to comment Share on other sites More sharing options...
idosubaru Posted May 17, 2012 Share Posted May 17, 2012 what he said - one can is not enough. nearly every subaru i've ever charged from empty takes 2 cans. somewhere on the radiator support/under hood it says something like 21-23 ounces - just about two cans. i have gauges and i don't even use them. i'm about to do my other H6 tonight, hopefully it holds as we want this car for vacation tomorrow! Link to comment Share on other sites More sharing options...
ShawnW Posted May 17, 2012 Share Posted May 17, 2012 You also apply a vacuum to verify that there are no leaks. I have so many pet peeves about the 134A. I am pretty do it yourselfer friendly but to me this one crossed the line. I have evacuated systems where people put 5 cans in, stop leak in, etc. I have found clutch problems as described above and people that were still just adding freon. The stuff IS bad for the environment and now everyone can go buy it and "fill it till the level is in the green". The cheap can top gauges are almost always completely inaccurate. Link to comment Share on other sites More sharing options...
nipper Posted May 17, 2012 Share Posted May 17, 2012 You also apply a vacuum to verify that there are no leaks. I have so many pet peeves about the 134A. I am pretty do it yourselfer friendly but to me this one crossed the line. I have evacuated systems where people put 5 cans in, stop leak in, etc. I have found clutch problems as described above and people that were still just adding freon. The stuff IS bad for the environment and now everyone can go buy it and "fill it till the level is in the green". The cheap can top gauges are almost always completely inaccurate. This is the one thing where i highly recomend they take it to a shop and get it done right the first time. I completly agree. Link to comment Share on other sites More sharing options...
ShawnW Posted May 17, 2012 Share Posted May 17, 2012 They don't even have to pay to have it charged. Pay to have it evacuated and vacuum tested. From there its sealed, dry inside, and empty of all the old Freon. Many shops will do it for free if there's a significant amount of Freon in it. I don't but I do it for a very reasonable price in the first place. Link to comment Share on other sites More sharing options...
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