Chriskaw440 Posted March 26, 2007 Share Posted March 26, 2007 My 1990 SE's AC is loosing its cool and that kinda sucks here in South Carolina!! It's always run great, and it was converted to the newer Freon by the previous owner (R12 I think....or is that the old one...either way...its the current legal stuff.) It's fully charged and doesn't leak, but the sight glass on the evaporator is all foamy when its running, indicating either air or moisture or both contaminating the system right? Basically, it seems to run just fine and eventhough its fully charged with good freon, it blows only slightly cool air through the vents.....and during the middle of the hot days here in SC, even with the windows tinted dark, it doesn't help much at all. maybe just the evaporator is bad? condenser? I hope not the compressor since it sounds and operates aparantly fine. I know this kind of work is best left to the pros for legal reasons but I don't exactly have a ton of cash to pay for replacing the whole system. anyone with AC knowledge your input would be greatly appreciated. thanks! -Chris Link to comment Share on other sites More sharing options...
meangreenmachine Posted March 27, 2007 Share Posted March 27, 2007 How do you know that it is fully charged. A slight over charge or a slight undercharge can render an ac system just about useless. Make sure the condensor is clean of all debris and dirt to maximize efficiency. Link to comment Share on other sites More sharing options...
unccpathfinder Posted March 27, 2007 Share Posted March 27, 2007 roll down the windows and drive fast umm my 87 had a slow leak/weak compressor and it actually got moisture in the system and after a quick recharge at a buddies garage it lasted for 1 summer until it got cold and then it lost its charge...i cant really remember how to tell if the compressor is weak but it seemed to be something with how much friction/runout was in the pulley... if it ends up being a compressor i've got 1 out of a 95 that was good and strong when it was pulled and its been sitting for about 5 months or so but it should be good i could let u get it for cheap if it would work for u're application... i would think a recharge should fix u're problem you can also check line temps and that might tell a little about the charge in the system...just be careful with the hot side lines b/c if its low it can get really hot Link to comment Share on other sites More sharing options...
John Boy Posted March 27, 2007 Share Posted March 27, 2007 Until you put some gauges on it you can guess all you want. Link to comment Share on other sites More sharing options...
Chriskaw440 Posted March 27, 2007 Author Share Posted March 27, 2007 I attached a gauge and its actually close to being overcharged, and the evaporator sight glass has foam/bubbles blowing around. It had a slow leak two years ago, added freon with leak sealer of course and it ran GREAT for about a year and a half, then slowly started loosing its cool, yet the gauge shows is almost overcharged. I haven't had a chance to do a line temperature test yet...to see whats hot or too cold. Been too busy killing weeds in my front yard! My local nissan shop says they would probably just suck everything out, then recharge it and go from there. I'm hoping its nothing major but I got some cash stashed just incase it gets pricey. Link to comment Share on other sites More sharing options...
Chriskaw440 Posted March 27, 2007 Author Share Posted March 27, 2007 Thanks UNC, I will keep that compressor in mind and see if it is compatible with my '90. My system was converted from the old freon to the legal stuff already. Link to comment Share on other sites More sharing options...
94extreme Posted March 27, 2007 Share Posted March 27, 2007 if it's the dealer, it's pricey for sure. you may have the right pressure and still be low on freon. the best way is to evac the whole system and then refill. i just used mine this past weekend, when wheeling, and man, it's awesome. Link to comment Share on other sites More sharing options...
Chriskaw440 Posted March 27, 2007 Author Share Posted March 27, 2007 I try to avoid the dealerships nowadays.... this is a local nissan specialist shop down the road from me....they are awesome, but last time I was there it was $70.00/hr for labor...probably more now thanks for the info!! I kinda get tired of riding around in my wifes ford van just to stay cool.....no fun can be had with that thing. (the van, not my wife....HA!) Link to comment Share on other sites More sharing options...
mws Posted March 27, 2007 Share Posted March 27, 2007 (edited) Thanks UNC, I will keep that compressor in mind and see if it is compatible with my '90. My system was converted from the old freon to the legal stuff already. **** Warning bells sounding! **** How much did the conversion cost him? If it was one of the under $100 "change the o-rings, dump in the special snake oil, and re-fill" jobs, then your compressor is probably now dying. As do 90%+ of R12 compressors after being "converted" to R134a. Fortunately for the companies selling them, they usually die several months after the conversion so they can't be held liable. There are some fundamental incompatibilities between R12 oils, R134a oils, R-12 and R134a. A system that is not fully cleaned before filling wtih R134a will die. Sooner rather than later. Now that your compressor is fried, it is time to do it right. You MUST completely evacuate and clean the system and get every last trace of R-12 and mineral oils out of there before replacing the compressor and hoping for the best. Most advise to replace accumulator and other parts as well. I know you hate to hear this, but you will be better off to take it to a very knowledgable automotive A/C specialist to be properly diagnosed and repaired. Yeah, they are expensive, but will save you in the long run. The cheap ones will just throw parts at it and bills at you until you go away. Edited March 28, 2007 by mws Link to comment Share on other sites More sharing options...
mws Posted March 28, 2007 Share Posted March 28, 2007 BTW, the R134a will never cool as well as the old R12. It just doesn't have the cooling ability. If you want to learn more, there are some interesting technical papers on this website: http://www.autofrost.com/ Link to comment Share on other sites More sharing options...
94extreme Posted March 28, 2007 Share Posted March 28, 2007 hey, the synthetic oils go with r123a then? Link to comment Share on other sites More sharing options...
Chriskaw440 Posted March 28, 2007 Author Share Posted March 28, 2007 Yeah I have no idea who or when the conversion was done, as I have had the pathy since 2001.... The nissan/import place I will most likely take it to is the best in the area, they dont fool around so I have faith in them. I heard the new refrigerant doesnt cool as well as the old stuff did...but oh well...what can you do right!! if its over a $1000.00 to get it all fixed I will probably go a different route....too much jack for a ride this old...but we'll see. thanks again! Link to comment Share on other sites More sharing options...
John Boy Posted March 29, 2007 Share Posted March 29, 2007 Part of a R134 conversion is pulling a 29 inch vacuum and holding that vacuum to ensure no leaks. This also in turn removes ALL the R 12 and it's oil. The fact that it's overcharged ( increasing your high side pressures) don't be surprised if the inside of the filter drier blew out and is blocking the expansion valve. Link to comment Share on other sites More sharing options...
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