82' 380SEL

When I bought the car the previous owner had put 134 on the A/C system.

I topped it off after I bought the car with 134 and it worked fairly well. Now year later another summer, it's getting a lot hotter in NY and the A/C does not work as expected.

I went to the auto store got a 134 can, started recharging but there seemed to be a lot left in the can, nothing going into the A/C system for some reason ?

Checked the pressure, setting control unit to full cold -> 25psi
Checked the pressure, setting control unit to off pos -> 10psi

Checked the window on the dryer, setting unit to full cold -> white frizzy / bubbly
Checked the window on the dryer, setting unit to off pos -> flow without any white bubbly stuff

So here are some Q's if anybody out there can educate me on the subject ?


1. I would like to know for how long would you hook up one of these cans to the system, for it to fully empty. 1-10 min ?

2. How do I know how much I need to add, not to over do it.
I would hate to put too much on there and have it ruin because of that. Is there any way to tell ?

3. What is the pressure supposed to be under normal circumstances, high and low end ?

4. Then to kind a start on another subject, the compressor is always on, no matter what position I set the unit on - off / ec / def / ac, doesn't matter it's always on. The only way to shut it off is to pull one of the wires off of it. Also the temprature of the engine gets pretty high between the 120 and the other line below, can't remember if it's supposed to be 80 or 90 ?


ok, enough for now, I guess I hope I will get some good input,

thanks,

Nobody seems to have comments ??

Maybe it's because I forgot to tell you guys that I did search and dig here on the board before asking. But obviously not enough, did more digging and got a little further.

Specially this post a/c high pressure reading

Those numbers helped a lot, I topped it off but only got the temp down to 68F, good enough, specially since it's good enough for the wife

I had that can hooked up for at least 15 minutes, running the car at 1500.

The pressure is 30psi now, I think it should be able to take more, but I'm not sure, better not risk it.

If anybody has a hunch why the Compressor is always on, no matter what, it would be great to get a hint.

Thanx,

It SOUNDS as if you are using manifold gauges to monitor both sides, so that's good. If you're not, then don't proceed. In a converted system you MUST be monitoring high side pressure.

Secondly, are you sure you are charging in the low side? I hope this question isn't insulting, but it is a safety issue.

Since this system has been converted, the sight glass is not very useful any longer. Also since the system was converted before you got it, you have no way of knowing what you're dealing with. Systems can be "converted" with a death kit from Wal-Mart or they can be converted properly including complete flush, proper filter drier, correct oil, evacuation and charge.

One last thing; if everything else is okay, no excessive high side pressure, charging on the low side, etc., you can put the can in a bucket of luke warm water to get the refrigerant to boil out of the can. Don't charge with liquid by turning the can so that the hose is at the bottom. The liquid can destroy your compressor depending upon the system type.

On a converted system it is difficult to know what the high side pressure should be. I hesitate to give numbers because there is educated guessing involved. If you have over 200 PSI high side and your low side is ranging around 25 to 35 pounds, you should have reasonably cool air. Remember you lose about 20% of your cooling capacity when converting to 134, so you can't expect too much.

Your system was designed for R12, if you want a cool, long lasting system, a proper reverse conversion back to R12 is what you need depending on your climate.

Good luck,

Thanx Larry, you say ... "you must monitor both sides" ok what am I looking for ?
I know you don't like giving out numbers since it varies depending on car / model freon etc,
but there has to be a reason for this, I have no clue.

I can't find anything like this on the cd, it's all about how to evac, rebuild, etc.

I'm pretty sure that I'm charging at the low end according to all the numbers I have seen, 30 psi should be the low end ?

In any case let's make sure, I'm using the plug that is located where the pipes get cold when the system is working. I'm NOT using the one which is really close to the radiator and the dryer. I took the car to a aircondition repair / recharge place in the beginning, that's the plug they wanted to use, so I thought I was pretty safe.

I did not want to put more on the system, it is cold enough. But I want to learn more about the system.

I really like the trick with the water for the bottle, mine became really cold, just as if it was part of the system, since I had it hooked up for a long time. I saw the warnings on the bottle DO NOT PUT UPSIDE DOWN etc did none of that.

I'm not using professional gauges, seem to be able to get them for around $75, which I will probably go for if I learn how to use them.