AC mystery 2000 Merc Mountaineer

[JimMadsen]

OK, I am going to sign off for the night and check back tomorrow. Can I check for a leak myself, or should I just take it in someplace and let them have at it.

Thanks again all

 

[CDW6212R]

The AC shop to do it right will vacuum out the system, and recharge it from zero, then you know how much is in it.

There are many places leaks can happen, every hose fitting, the clutch area, compressor body, and least likely the other hard parts. Any time the system is opened for repair, have the several o-rings replaced. Also buy locks for the quick connects if you can get them, the OEM plastic things aren't that good.

 

[JimMadsen]

Well I added in some more from the can, but had to stop early. The compressor was doing the same thing. Outside temp is 80 degrees, gauge should be 45-55 psi per the chart on the can. Went up to 57, compressor spun and it dropped to 25 just to repeat over and over. I added a bunch in and it was still warm air. I then happened to switch from max ac to vent at 65 degrees (no change). I still had the gauge on and the PSI was at 98! I stopped at this point. I turned off the car and left the gauge on for a couple of minutes, needle stayed put. So I will check the very high psi come the morning before heading to work and if it is still 98, can we rule out a leak? And can it stay that way for a bit or does it need a vac quick.

 

[my98nnj]

Outside temp is 80 degrees, gauge should be 45-55 psi per the chart on the can. Went up to 57, compressor spun and it dropped to 25 just to repeat over and over. .

I think I see the problem. Your not understanding the pressures your seeing.

The psi reading on your Gauge (green area) is where the system should be when the compressor is running. Your charge is still way to low, causing the compressor to cycle off the low pressure switch. The click "compressor on" and psi pull down is what you need to bring up into the 45-55 psi range. At 25 psi the low pressure switch is inturrupting the compressor cycle for safety reasons. The click "compressor off" pressure increase to 57 is the system equalizing and then the low pressure switch closes (cycle repeats).

Your static pressure 98 (system not running) is still very low, it should be over 100 psi and isn't what you need to look at.

Put more refrigerent in, it should take 1lb, 14oz. (almost 2 lbs) to fully charge. Depending on how quickly it's leaking out and how effective your stop leak charge works, you might have cold ac for a while. If it stops working soon after you get it charged correctly, the leak should be easily detected and repaired by a qualified ac technician.

 

[CDW6212R]

The pressure will equalize when it's all off, and that will be much higher(on the low side) than when it's running. The high side may hit over 200psi while running, I'm not sure what that normal pressure or the high pressure switch rating is.

The R12 I have in my 91 Lincoln is supposed to cause shut off(cycling) at about 40psi. I have very little cycling in that car, it runs very often for a minute with no clutch cycling.

It does look like you just have a leak, and too little freon right now.

 

[JimMadsen]

Ok, whew, I got worried about that. My wife has it at work until 9 tonight and then I can check it again. This am with the system off it was reading 65 psi. So was that equalizing, or just leaking out. Should I just keep dumping more in until the compressor seems to be happy? I used to be a paramedic and play paintball a lot so I dealt a lot with high pressure cylinders. It is worrisome when you don't know the max pressure and the gauge is in the red!

Since it can take 30 ounces, should I finish off the 18 oz can, and if nothing, add in a smaller half size amount?

Thanks again all for the help.

 

[CDW6212R]

It's your judgement. If you think it is leaking bad enough that adding more isn't going to help until the leak is fixed, wait until you get it to a pro. I'd go by the gauge since you have one there. If the pressure you are seeing isn't dropping(in steady conditions) too fast, add some more freon. It may be that it will leak most of anything you put in, in a day. That would not help you much and the shop would have to add some more to use a detector to hunt for leaks.

 

[Turdle]

Are you sure he should be adding freon? I thought all after 1995 were r134a refrigerant.

 

[JimMadsen]

Are you sure he should be adding freon? I thought all after 1995 were r134a refrigerant.

I have been adding r134a, not freon. A freon can will not fit on a r134a port. It has been my exp that people over a certain age (myself included) use the term freon for anything you put into the ac system to charge it regardless of what it is actually called.

 

[CDW6212R]

Yes, I mentioned the R12 in my one car just to say the compressor should run for a long time, more than a few seconds per.

 

[sshanky]

Good thread. I have been helping my friend with her 2000 mountaineer with her ac as well. She's never had to add any refrigerant until this year. We live in Arizona. Her air was warm at idle and barely cool driving. I connected my gauges and added 1/2 a can i had left, then a full can, and it got much colder. The pressure was about 35, and it was about 100 out, so according to one simple chart I found online i should have been at 50-55, so I decided to add a second can. Total of 2.5 small size cans. How many pounds are in one of those small cans? I got the generic r134a from walmart for 9.99 a can. Now, her air is still not as cold as she remembers it being last year, and I started wondering if I overfilled. I checked again yesterday, about a week or two since we did the filling, and my gauge reads about 35 lbs at 1500 rpm and 102 F. So...questions, if you don't mind, are:

1. how many lbs per small can? Am I ok using the cheap stuff or should I pay for the stuff that claims to be colder?
2. what happens if I overfill? does it start to get warmer again as you exceed the right amount?
3. Can anyone point me to a good chart? I've looked at a lot but don't understand most of them except the simple ones that have ambient temp and then high and low side pressures, like the ones that come with the cans you buy at the auto parts store. the others seem complicated but I'd love to learn how to read them.

Thanks a lot!

 

[blueoval9erlifer]

find out what the gauges should read and go by that if your not reclaiming the freon and starting from scratch how do you know how much is already in there. also make sure that the condensor is clean, a lot of times if you spend 30 minutes and wash out the condenser it makes all the difference in the world. If it can not cool down then it wont blow cold