My air conditioning problem :(
 

Ok, so my ac does not work. Being in Phoenix, it is already starting to get hot. So I really need my AC working. I was working on a previous thread to try and resolve the issue. Since then I have read tons of AC articles and posts. So I think I know the ac system much better than I have before. Ok so here it goes:

I notice when I run the AC, it makes a hissing sound whenever it is on. From what I have read so far, that is either going to be a vacuum air leak or low freeon, gas instead of liquid hitting the expansion valve.

It makes a hiss that sounds like a combo of a tire going flat and a gas line.

Is there any quick way to diagnose which one it could be?

Random info:

The compressor, when running, has one side hot, the other side warm.

The reciever/drier is cold to the touch, including the lines before and after the drier assembly.

Would my best bet be to start looking into the vacuum system to see if it is just allowing fresh air instead of ac, or should I start looking into a recharge of freeon?

Thanks.

it sounds to me like you have a stopped up screen in the liquid line upstream of the receiver. I would start there. get a set of pressure gauges and check what the pressures are.
the reciever drier should be warm to hot depending on the ambient temp outside, and the return/suction line on the compressor should be cold.
John

Trace the highpressure line and make sure its not leaking anywhere.

IMHO, your best bet would be to buy a gauge set and see what the pressures are. Those pressures are very informative!! :D

Where is this screen at? I happen to have a brand new reciever drier, need to get a set of pressure gauges at harbor freight this weekend (on sale this week for 30 bucks). So I could get the system evacuated, put in a new drier, and then get that screen cleaned right? Is the screen before the expansion valve?

Now I had another question as well. Are the answers I recieved about the compressor, and drier specific to our cars? Reading some info on other sites say that the reciever drier should be cold to the touch, and one side of the compressor should be warm other should be hot. The information I recieved above tells me different - so thats why im just curious as to if this info is specific to our cars. Thanks!

most american cars have accumulator driers. they are in the suction line and they will be cold to the touch. our cars filter the liquid out of the condenser, so it should be no cooler than ambient air, if not warmer.
John

Got it, thanks for the clarification. Of course I will get the pressure gauges, but from what is known so far, does it sound like I will probably need to evacuate the system, replace the reciever drier, and then also the expansion valve? Or is the screen before the expansion valve?

before.
EV should be fine.
John

Be careful with the cheap guages they are known to fail. Also are you using R12, Freeze 12 or 134?

Replace the drier and expansion valve first. Evacuation is the last thing you do before adding freon. It would be a good idea to flush your system as well, add the proper oil, then button it up, evacuate it, then add freon. You should have the York compressor. Check the body of it for leaks.

On our systems the drier is usually quite warm.

true evacuation into a vacuum is the last thing before recharging, but I believe he is stating that someone needs to remove the "deadly ozone depleting freon" before opening up the system and replacing bad parts.
nobody wants to admit to releasing into the atmosphere such a nasty substance... right? I mean there is a 10,000.00 fine for such a crime right?
or is it a 10,000.00 reward and a 50,000.00 fine... anyway, best to claim you are doing it legally.
John

I am using r12 (from what I know, have not had the car for too long). There are no retrofit adaptors so thats why I assume r12.

And yes, when I say evacuate the system I was talking about having someone remove the "deadly ozone depleating freon" lol. And of course I will have someone do it for me, so you wont get your reward lol. Is it really as bad as everyone says?

Anyway, time to start researching how to remove and install expansion valves - if anyone has any tips or tricks, I would appreciate it.

Are you staying with R12? I would suggest it... especially if A/C is a priority!! That being said, the PO converted my SD to R134, and when I was in Phoenix the A/C did really good (temps were in the low 90s, upper 80s). Vent temps were around 55-60* there. That doesn't sound all that good (and it isn't), but here in Mississippi (90%+ humidity) it rarely goes below 70* for the same outside temps. Just some datapoints for ya...

If your car is a 1981 300SD.... it is buried underneath the dash. It can be done without removing the dash, but you are upside down in the drivers footwell for a few hours... my W116 has it in the same spot I believe. I've never replaced one though... :worried2:

I think you should have an R4 compressor instead of a york...

Before you replace anything (or give away that R12!!) you need to look at the pressures. It might just be low! :dizzy2:

R12 isnt as bad as they say it is. It is flammable, as compared to the non flammable r134, and it tends to cool better than r134. It is bad for the ozone, but most people think that one car wont make a diff if you let it out, but it kinda goes with the saying, that if everyone does a bad thing then you have a problem. The reciever drier on automotive as well as refrigeration systems should be warm to hot depending on the temp outside like another member said.

My compressor in my 83 300d seized and ripped the belt off before I even go the car, so I am going to be replacing the compressor pretty soon, before it really starts to get hot here in so cal.

Is there any place that i can get a descent compressor, besides the local euro shop which wants an arm and a leg for it?

Try Fastlane (the people who host this site). If its not online, call them... only a fraction of their stuff is online.

http://catalog.peachparts.com/

:D

I don't think that you have a screen. I suspect that references to a screen were generic in nature.