You have no idea what you are dealing with. Take it to a shop.

 

 

 

Glad you are willing to learn, and dive into things, but this is different. Car AC systems are not just mechanical or electrical stuff; they require significant knowledge and skills to safely charge, and balance a refrigeration system. AND, R-12 is very expensive, and you could easily spend $200 , just to have it all leak out the next day. Let a shop diagnose the problem, then see if you are willing to spend that kind of money to fix it.

 

 

This is a good resource if you haven't seen it already:
http://www.lexls.com/tutorials/air/accodes.html

On these systems if the A/C clutch is operating and not blowing cold, there is likely a leak to deal with.

 

Welcome Joel. I saw your other post - very nice find! To answer your initial question, yes, that is the low pressure port where you can recharge the system.

You brought up a good point about the shops. R-12 refrigerant is no longer used, and many LS 400s were converted to R-134a because of the negative impact R-12 has on the ozone layer of the atmosphere. If you do take it to a shop or a Lexus dealer, they may indeed try to convert your car to R-134a, but I cannot confirm this.

Unfortunately, I had the same problem with my 1991 LS, and was able to fix it 2 years ago. However, as RA40 mentioned, the reason why the A/C is no longer blowing cold air more than likely is because of a leak.

The process of diagnosing this leak is not easy either, and will require a decent amount of disassembly and testing.

In my case, I had to remove the air assembly, up to the MAF sensor, the battery and battery tray, and the headlights to expose most of the A/C lines and test them for leaks. I used a combination of a sniffer tool and a refrigerant with UV dye to find where all of my leaks were, and bought a set of seals to replace the old, dried up ones.

Note that it is illegal to release refrigerant into the air, and that only a professional is allowed to dispose of it properly.

There is a tutorial on LexLS.com describing how to recharge the system, but this will not be permanent if you have a leak.
http://www.lexls.com/tutorials/air/acrecharge.html

 

It is definitely possible to maintain your R12 system, especially since as you say you're willing to learn what you need to do it right.
On my '91 (still on R12), I similarly had low Freon, turns out due to a slightly leaking low pressure port Schrader valve.
I bought a special tool to swap out that valve core, with the system still pressurized.
Then I filled with R12, and it's working great. I had to add another can after a few years of the initial repair, so the system is not 100% tight, but yes, still working great.

Steps I'd do (off the top of my head here):
Run the built-in diagnostics to check HVAC codes. Make sure there is nothing there that could be the problem before diving into R12 issues. If you do the test in the dark, you'll get a light sensor error that you can ignore.

Try to observe the compressor kicking in - RPM change, sound change, visual on the AC compressor

SNIFF for leaks. I bought a Snap-On halogen sniffer on eBay for pretty cheap and it works great on R12 and R134a systems (so I can maintain my whole fleet). Non-invasive, unlike the UV dye stuff. Instant. Do it anytime you like.

If you want to check something without dye or a sniffer, you might learn something by removing the plastic cap off the pressure ports. There may be some pressure build up that you can hear when removing. Or put your finger over it and see if any pressure builds up after a little while.

Once you find the leak, if it is a valve (I believe this is the most common one), you may need to just tighten the Schrader valve core within the port. Or maybe you'd need to replace it, using the special tool I mentioned above (many details posted on this site regarding that).

Either before or after finding the leak, pressure tests will be helpful. The service manual has very specific procedures and specs for these tests.

Once the leak is fixed, add refrigerant as needed.

Some will just skip all the above and add refrigerant. Many of those will be successful, but maybe not.

Good luck.

 

I have seen this post. but my clock panel is blacked out dx.... it only sometimes turns on and I am able to see the time and tempature

 

I am sher my car does have a leak and I am saveing up to get that fixed for sher but for now is it safe to just refill it an see how long that goes?.

 

I am sher my car does have a leak and I am saveing up to get that fixed for sher but for now is it safe to just refill it an see how long that goes?.
Oldskewel and everybody thank you for all the info very much appreciated keep you all updated on the work as the week progress. Danm day job getting in the way xD

 

The larger diameter lines are the low pressure lines that is where you add the refrigerant. And the one in the picture looks correct its back by the RH firewall area. The old R12 ports on both high and low lines are the same type of fitting. There is a hi port under the airfilter and there is also a port near passenger head light, don't remember the pressure on that one. If you try to add into a high pressure line with compressor running it could rupture the can your filling with so be careful, your best bet is to have a manifold set to do it, harbor freight has them. All the lines need the air evacuated when filling or you just add air to the system.

 

If you're really sure you've got a leak, and can safely add a can, there's probably no reason to not try it.
If you've got a slow enough leak (for example, you'll need a new can every 5 years or so, which is about what mine is like), that may be the way to go.
If your leak is a lot faster than that, you'll find out soon enough and it will be useful to know.

Still, I'd at least feel for a leak at that low pressure port valve. Make sure it's clean, etc.

 

Hey everybody so I topped of my A/C it was surprisingly easy to do and buy thanks everyone for your help