testing A/C.. where do I start and what do I need to know?

[THe_DeTAiL3R]

Okay I'm a real n00b when it comes to A/C since I've never had a car with WORKING A/C. I'd like to see if I can try to figure out what is wrong with mine if possible, cause it would be great to have it working. I don't know anything about A/C systems except where the compressor is loctated, and that there are lots of tubes that go everywhere, and there's a can thing under the battery area .

 

 

So any advice would be appreciated. Remember, I'm an idiot when it comes to A/C stuff so you'll have to explain how the stuff works and what the parts do in order for me to understand.

 

Thanks

[DiscoStudd]

First off, remove your airbox and locate the "accumulator." It sits right under the airbox and is basically a silver "can" with pipes attached to it. Look for a "Schrader" valve (it kinda looks like a tire's valvestem) near the accumulator. Remove the cap and depress the valve quickly to see if anything sprays out (don't worry, it'll only be vapor, but don't hold it down more than a second otherwise you'll freeze your finger off.)

 

If anything comes out (with any kind of force) then it's a safe bet that your system is at least partially charged and would have enough pressure to allow the compressor to engage. If this is the case, then you probably have an electrical problem (relay, fuse, possibly the PCM.)

 

If you get nothing when you depress the Schrader valve, then you need to charge up the system. Luckily R134a is cheap and readily available. Go to Wal-Mart or your local parts store and grab one of those cans of refrigerant that has the hose and gauge already attached to it. The hose only attaches to the "low" pressure port, so you don't have to worry about accidentally adding refrigerant to the "high" side (which is dangerous.)

 

Getting back to the PCM thing, if the PCM detects low refrigerant pressure, it sets a "soft" code in memory (it won't illuminate the SES light) and will not allow the compressor to engage, even if you add refrigerant, until you clear out the code...

[GutlessSupreme]

And what if you have no pressure because of a leak? Do they sell dyes to track down the leak? Where can I get them?

[DiscoStudd]

And what if you have no pressure because of a leak? Do they sell dyes to track down the leak? Where can I get them?

They sell a stop-leak with a red dye in it. You might want to try tightening down all of the connections on the hoses and pipes to make sure none of them worked themselves loose before you go the stop-leak route...

[DaveFromColorado]

ya know, that's a good way to do it, but I'd on top of what DiscoStudd is sayin' I'd pay the few $$ to go to a shop and have them evacuate the system, and then pull it down into a vacuum, that way you get all the old stuff out of the system, along with any water that may be in the system, this is a good time to see if there's any leaks, if it stays in a good vacuum then you should* be okay, it'd be at that point when you add the oil/stopleak/dye charge, then the 134a charge and that should get your AC blowing cold again.

 

--Dave.

[Cutlass88er]

Speaking of R134a, do all Ws support it. I remember being told that my 88 cs didn't support that stuff. What year did GM make them compatible?

 

-d

[1990lumina]

Not all of them are compatible from the factory do to age, but you can buy the retrofit kit to make them all compatible.

 

I'd guess it was either 95 or 96 when GM switched to CFC free refrigerant

[GnatGoSplat]

Do not put any stop-leak into the system. The A/C guys say stop-leak products cause "black death". Find the leak, then fix the bad seal.

Most leak detecting kits I've seen have a UV dye in it. You use a special UV penlight and yellow glasses to see the leak (it will flouresce). You can get the UV dye in pressurized containers so that no additional tools are required.

 

You can put R-134A in all W-bodies if you evacuate the R-12 first. You will not get optimal cooling with R-134A unless you replace the orifice tube. You might also want to replace the control valve in the compressor. For some reason, my 89 works REALLY well on R-134A, but I think that's because something plugged the orifice tube just enough to make it cool well! On my other car that I simply switched out the R-12 for R-134A, it doesn't cool nearly as well.

[1990lumina]

so the orifice tube is smaller for R-134a??

[Turbocharged400sbc]

R134a is a smaller molecule so yeah it has to be smaller for proper evaporization....

 

one of the reasons an r12 system doesnt cool as well with 134a in it, the smaller molecules opperate under (a little) higher pressures to get the same thermal transfer efficiency as the larger molecule r12...

 

also there are some good books in public library's for more info....

I know no one likes to go into a pub library but they are handy....

James

[1990lumina]

Yeah that sounds like me....how about any good websites with some info on it lol 8)

 

I'm just lazy, plus the basement is being torn apart and I can't really leave the house...but something to look at on the net should be good. It is so fucking loud right now I'm going to go insane lol

[Turbocharged400sbc]

find on of the "How it works" sites and youll get some info (quiet inside public library )

 

also when converting to 134a (just remember'd) i highly recomend replacment of the accumulator along with draining of the system ester oil as PAG oil is recomended for some r134a conversions and polyol ester recomended for other systems being converted to r134a (all cars equiped with 134a from the factory require PAG oil (100 or 150 weight)

 

also do not use system stop leak/conditioner!!! it can cause compressor "black" death (usially cause all the insaides of the alum pipes are coated in black crap) but it will seal the leaks for a while till the compressor dies. (use if you are gonna sell the car )

 

also google Harrison or Delphi as they are two manufactures of GM AC system components, they may have more info fer ya!

 

James

[GnatGoSplat]

one of the reasons an r12 system doesnt cool as well with 134a in it, the smaller molecules opperate under (a little) higher pressures to get the same thermal transfer efficiency as the larger molecule r12...

 

A new control valve will take care of that. The control valve is the only difference between a R-12 and R-134A compressor. They are REALLY easy to change. With an evacuated system, all you need are snap ring pliers, flathead screwdriver, and some Nylog assembly lube.

[DOHCRagtopguy]

1993 was the last year for R-12 on Cutlass Supremes.

[THe_DeTAiL3R]

UPDATE:

 

Well I had "cool" air for about half an hour today!

 

Here in Canada we can't buy R-134A cause you have to have a licence to use it. So I bought this retro kit stuff called RED TEK which is "environmentally safe". Designed to be direct replacements for R-12, R-134a, R-22, and R-502a.

http://63.135.115.175/products_refr.html (click on the "RED TEK® Kits")

 

As soon as I finished off putting in the first can, the compressor kicked in . THEN smoke started to come out of the area around the top left side of the radiator. :?: I drove around for 15min after finishing putting in the second can.. I'd say it got about 2/3rds (at most) as cool as a fully working A/C. I did use the LeakStop stuff which didn't help with the smoke or leak. :| After I turned the car off I heard the system slowly leak out.. which all leaked out in about an hour.

 

So what could be causing the smoke? It's like right behind the headlight area.. by the radiator. It was too hard to tell exactly where it was coming from. I think i'll take it to a shop to get it fixed (now that I know it CAN work...)

[DiscoStudd]

It likely wasn't smoke that you saw, but the vapor of the refrigerant escaping. Sounds like you either have a leak in the condensor (which is in front of the radiator) or one of the hose/pipe fittings is loose. Try tightening down on the condenser fittings and add another can of refrigerant and see if it leaks out again. I'd say the condensor has a hole in it somewhere if snugging down the fittings doesn't take care of the leak...

[THe_DeTAiL3R]

Would the vapor be white in color? Looked like white smoke (like from a soldering iron, but more), however it didn't really smell "burnt" so maybe you're right. Where is the condensor.. in front of the rad (facing outside the car) or facing the engine? I don't know where my damn Haynes manual went.. :x I wanted to look closer at it but my engine was real hot (gotta change the t-stat and coolant AGAIN ) and I was pressed for time.

 

God, if this is a cheap fix I will be SOO happy! Kickin' myself for not doing it sooner!!!

Wonder if my old 88' GP just had a leak... 4 years of hot driving sucked. The car is at a pop-can factory now so I'll never know.

[Canada]

R134a is colorless.....but who knows what this RED TEK shit is.

 

Sounds like you could go for a new condensor....its right in front of the radiator. New units aren't cheap....and junkyarders usually are leaky.

 

You need to find were it is leaking though....it could be from a bad O-ring or a hole in a line.

[THe_DeTAiL3R]

R134a is colorless.....but who knows what this RED TEK shit is.

 

Sounds like you could go for a new condensor....its right in front of the radiator. New units aren't cheap....and junkyarders usually are leaky.

 

You need to find were it is leaking though....it could be from a bad O-ring or a hole in a line.

 

Also, when it was leaking (with the car off, or before the compressor really kicked in) there was no color. Unless possibly the high pressure of the A/C running would cause it to turn color? Is it possible that there is water or oil that the condensor is burning?

 

So "In front" of the radiator is the opposite side of the fans then? (I get confused sometimes). If so, is it alot of work to get at (for removal?)

[DiscoStudd]

The radiator is closest to the engine and the condenser is closest to the grille.

 

The "white smoke" you describe is exactly what refrigerant looks like when it pisses out of the system (if you ever happen upon an old window AC unit, cut open one of the lines and you'll see exactly how refrigerant acts when you release it into the atmosphere.) Most of the time you'll get some of the oil pissing out along with the refrigerant, but you'll definitely see a cloud of "white" ...