Hello,
I now, it's wrong place to put it... But I tried HVAC forum and have not received any replies...
I don't believe that no one has no experience with the issue. So let me copy the question here.
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I have some general questions on how (if it's a good idea) to add some refrigerant to AC system.
I have '97 SC and even though the AC works it looks like it doesn't cool as good as it was last year. I am planning on buying some R-134a and an adapter. I've went through the manual but still want to make sure that I'll be doing this correctly.
I would appreciate if some one cold point me in the right direction…
The first thing is where is the low-pressure inlet where I'm supposed to connect the adapter. I found the dryer right under the main fuse box on the right side of the vehicle. The dryer has an inlet on its side. Is this it? Or I am missing something…
Second, do I need to have R-134a with or without oil?
Thanks much in advance,
Alex.
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The fitting on the _dryer_ should be the low pressure fitting but:

a) I highly recommend that you get an AC book if you are going to do this yourself. There is a wealth of info on A/C charging and trouble shooting. In addition to low freon, you could have moisture in the system (new dryer required), a bad expansion orifice, a partially blocked line or inlet in the compressor.

b) For all the above reasons, you need a set of gauges. First, you can monitor pressure before you accidentally blow a can up in your face by connecting to the high side. Second, an overfilled system will not cool well either and can damage the compressor. I don't think the sight glass is present anymore. Third, you need to know the differntial between hi and lo when running to correctly diagnose the source of the problem.

c) As for oil, you almost never need to add oil to the system. Small leaks let freon escape as gas... unless you were to find a lot of oil around the leak (and I do recommend finding the leak as part of the process), I wouldn't worry about it.

 

I haven't messed with ACs in many years and then decided to add a pound of freon to my system a couple weeks ago. While snooping under the hood of my 2000 5.4L Expy, I noticed that I couldn't accidently add freon to the high side inasmuch as the high side fitting is completely different than the low side and the recharge hose coupling I have would only fit the low side. I think the older systems used the same size hose fittings, but I'd sure hope all modern vehicles have different size fittings. You can almost bet the low side is the much more difficult fitting to get to.

You can buy an inexpensive gauge kit (~$20) that will be sufficient for adding a can of freon every now and then (watch your pressures), but as the previous poster stated, you could have much more serious problems...best left for the professionals.

 

Thanks much for the replies! I appreciate it!
That's amazing...
I actually posted pretty much the same questions to another forum directly related to AC systems and had gotten pretty much the same response!
So it is not do-it-yourself project, right?
I do know that the adapter will fit low-pressure side only, I was not sure on where the port is...
As the last quest can you answer this…
If I should not mess with it why on the earth they sell the R-134a gas and adapters all over the places?
And one more time: Do you think that it is no-no?
Thanks,
Alex