280ZX_AV8R

Lately the A/C didn't feel as cold as usual (maybe because it's getting hotter,101 degrees!!) So I got some R-12 freon (yes you can still get it but you have to be certified) and some gauges I already had. Alright this is where it gets wierd. The low side was at 110psi. The low side is usually 40-60 on GM vehicles. Is the low side supposed to be at 110psi? No, I didn't put any freon in it, I figured 110 was way too much so I will leave it alone until I get information. While taking the hoses off the low and high side som small amount of freon may have come out so it is probably at about 105 now. Now the A/C feels a lot colder so I will leave it alone unless there is too much freon in.

terry x z

sounds like u were experience a vapor lock. i'm no a/c tech but from what i understand of how the gas is accumulated and then recompressed along with the high press.you mentioned, sounds like you aleved some of the problem allowing some of the gas to pass thru whatever proportioner it uses(orifice,valve).

Pistolio

while we are on the subject of aircon's, when shedding pounds from a car the a/c is always the first thing to go, just how much does the a/c and all its components weigh in a zx?

one of my z's is missing the compressor from the aircon so i was going to take it all out, i mean whats the point if it don'd even work.
just wondering

Ryan82ZX

Hey, I was reading and the low pressure is suppose to be 40psi. Terry may be right on this one, You may have a clogged orfice tube or reciever drier. Just a thought!

s/cL3.0

The A/C and all affilliated parts came out to 102lbs.. That was on a bathroom scale, And when I say all affiliated parts I mean it.. I took mine out about 5 months ago {big mistake now that it is 112 outside}

280ZX_AV8R

Went outside early this morning, started my car, turned on the a/c. HOT AIR!!!!!!!
Somehow all the freon leaked out overnight, I don't know how, everything was like it was supposed to be. So today I converted my car to R-134a. Perfectly freezing at the right psi. turn the a/c on low and it hits around 20 degrees. Turn it on high and about 35-40 degrees. Reason: lower velocity of air=colder air.

CWHammer

AV8R - how expensive and difficult was the change to 134? My '83 doesn't cool the pass. compartment very well and I was thinking about the conversion too.

jfairladyz

R12 is actually far more efficient at cooling than the r134 refriferant. The only reason it was put out of production was for environmental reasons. It does cost a lot more to recharge than the r134 though. So if it's maximum cooling you want, especially in hotter climates, than I'd just get the R12 system serviced. r134 works great, but it doesn't have any benefits over R12 other than cost and the environment if you actually vent it to atmosphere(which is illegal with either refrigerant).

280ZX_AV8R

All you have to do is buy R-134 refrigerant, a can of oil charge, and the guages to install the 134 into r-12 plug-ins or whatever the highand low side is.

You can convert the high/low side valve things from R-12 to R-134 for maybe 10-15 dollars, I think. You need to get about 3 cans of R-134@$10 each and the oil charge @ $5. comes out to $35 if you already have the guages.

Heres how I did it.........
I already had both the R-12 and R-134 guages so I just screwed the yellow hose that allows you to put the R-134 into your car onto the R-12 guages, and connected it to the lines and put the refrigerant in. Make sure the R-12 is completely out of the system before you do it.

jfairladyz

The only problem with the way you did that is that R12 hoses were not designed to contain r134a refrigerant. For two reasons. 1) r134a operates at a higher pressure than the R12 and the hoses arent designed for that. 2)r134a is a much smaller molecule than R12, so over time it will seap from your system due to the fact that it operates at a higher pressure. If you look at the end connectors for an R12 system and then compare them to an r134a system, you'll know what I mean. And the compressor may not last as long either as it wasn't designed to contain r134a and it's oil. In most R12 compressors, the seals will deteriorate with r134a because of the oil in it. And last but not least, is the reciever drier. You didn't mention changing the receiver/drier/accumulator. You should definitely change that when switching refrigerants, because inevitably, there will be R12 contamination in it. But the most important part of any system change is putting it under vaccum to boil out any and all moisture and to ensure absolutely all the R12 is evacuated. If not, it's only a matter of time before the system stops working efficiently. Now, non of this stuff will cause any damage, expect if the compressor isn't up to the task(alot of the old R12 compressors will work).

The most important thing to do is to change out the rubber lines for r134a lines (they have the proper valves too), change the receiver/drier(accumulator), make sure the compressor is up to the task, ensure the system is comopletely evacuated of R12, put the system under vacuum to get rid of absolutely all moisture(and ensure you don't have any leaks). The vaccum part is always neccesary because when you change anypart of the system or open the low side, you WILL get moisture in the system. You may not notice the adverse affects at first, but it's only a matter of time.

And for those wondering, yes I am certified to work on ac and yes I've done this for a living. I'm not trying to rock anyones boat here, but if precaution isn't taken, then it's only a matter of time before it comes back to haunt you, trust me.

jfairladyz

Oh, and the condensor and evaporator will work just fine given that you have the hoses are compatible with them. Even the OEM accumulator will work, I'm just saying change the used one. And most r134a compressors are smaller and lighter than old R12 units. If you can retrofit a Honda compressor to your L28, you'll save yourself a bunch of weight. But all this work it takes to do it right is definitely worth it in the long run. R12 is just going to get more and more expensive. And replacing parts because you did it wrong the first time will start to add up.

And on a side note, there are certain oils you can buy that will work with old R12 compressors. I recommend a different compressor but the oil is cheaper and will get the job done, though not as efficently.

280ZX_AV8R

yea, i forgot to say about pulling a vaccuum. And the guy who owned the car before me had some tech fix the A/C so it might have already had 134 in it. I have converted my other vehicle to 134 and have had no problems with it, and that was about four or five years ago. But the way you said would probably be the best way anyway.

jfairladyz

Some systems, mostly the later R12 systems can handle running 134, but may need to be serviced more frequently. But older cars like my mustang with its york compressor probably couldnt have handled it too long before the compressor gave out. It's hard to tell which cars will take to it and which will have problems until it's actually done. I've never personally tried to just put 134 in a r12 system, but I have seen some of the effects it's had on the compressor. Oh, and another thing is the service ports. The R12 ports can tend to leak on the high side with 134 in them if they're even the smallest bit loose or worn. But most often than not, when I did see problems from people doing this "cheap conversion" (cheap reffering to cost), the problems were more so from negligence on the part of the "converter" thinking they could just "vent" out all the R12 and then buy a bunch of cans of 134 and recharge the system. Then, when it doesn't work, they try to cram more refrigerant into it and make matters worse. Too much refrigerant and you blow hot, too little and you blow hot. You gotta get it within specs to get it to blow cold. The fact that you bought the oil and pulled a vaccum on the system tells me you atleast took the right steps toward making it work. And for all I know, you could end up never having a problem. But I do recommend a FULL conversion to anyone who's got the money to do so because you KNOW it will work for a long time to come. Yours worked, so I'm happy for you and you still got money in the bank .

ZedZilla

j, that was some very very good info. You certainly know your a/c stuff. I know its all accurate as well.

I just finished helping out a certified installer with an a/c install here at my house. So I definately undertsand the importance associated to ensuring a leak free system, as good a vacuum as can be achieved (no perfect vacuum exists other then in a lab maybe) and careful monitoring to purge the system as well as take out any hint of moisture. I see that all the same rules apply to automotive systems as well.

280ZX_AV8R

So far my a/c still works perfect, if it does go out, jfairladyz will be fixing it with his expertise in automotive climate controlling. I mean it, too.