Where do you add freon to the 355 AC system?

If like the 348 (which I suspect it is) then you are correct, you will have to remove the liner to get to it. Below the windsheild, slightly to the passenger side.

 

I would guess under the front trunk liner. But just to be clear, based on their build dates, the 355 presumably came with an R134a based AC system, so you would not want to use Freon (a brand name for R12 refrigerant).

 

Need to remove the rear portion of the liner nearest the windshield not the entire liner. Pull off the part of the rubber weatherstripping that surrounds this piece first, then remove the 4 small phillips head sheet metal screws that are in the trim piece around the HVAC unit. Remove the access covers over the battery disconnect switch and fuse box. There will be 2 phillips head machine screws under each that need to be removed, There is molding that is between the pieces of the liner that is held on with phillips head sheet metal screw. Depending on how the liner is cut you may just need to loosen up the screws. They are fairly long so you should be able to back them out and see if the liner is cut out around them or if there are just holes.(mine was a combination of both) If only holes you will need to remove the screws/molding on the rear piece. On the side pieces you can leave the front most screws in. There are also should be 2 phillips head machine screws that go through the rear liner into the side liner pieces. These are the same as the ones under the access covers and can be somewhat hard to see since the heads are black. They also aren't obvious on the parts diagram. After everything is removed and loosen, carefully lift the liner out to exposed the R134A ports. The liner backing is rather delicate so try not to flex it to avoid cracking it. It sounds like this takes a while but it really goes pretty quick. I did cut the liner out around the molding screws where there were just holes which made installation easier.

 

The ports should be two different sizes and may or may not have colored plastic caps on them. The R134A is added to the low pressure side (blue) which is the larger of the two ports. If I recall correctly it's the upper one. The connection is a special size quick connect designed for R134A only. You can either purchase one of the DIY kits that have a gauge (AC PRO etc) , get a separate inexpensive low pressure gauge or go all out and get the entire gauge manifold which has both high and low pressure gauges. The DIY gauges will probably be marked with yellow, green and red zones. Just add the contents until the gauge gets into the green zone. Fully charged its probably going to be around 25 -30 psi if the gauge is marked that way. You'll feel the can and low pressure line getting colder as you add. Make sure the AC is on max. cool as you're doing this. Might want to wear gloves also.

 

There's an important step that a lot of inexperienced people miss-- when you first connect the hoses to the car and to the can of refrigerant you want to bleed the air out before you start charging the system so you don't wind up with the air/moisture that's in the hoses getting into your A/C system. On a normal gauge setup you'd connect the hose to the car fitting with the all of the valves on the gauges closed. Then you would loosen the hose that leads from the car at its fitting on the gauge and purge the air from it. Next you would connect the can of refrigerant to its hose and then bleed that hose by loosening the fitting at the gauge. Only then would you open the valve to admit refrigerant into the A/C system.

Another tip: it helps to immerse the can of refrigerant in hot water while you're charging the system, assuming you're using the small cans and not a 30 lb cylinder. It also helps to have the car set to a fast idle-- 1500-2000 RPM should be about right. A/C set to coldest temp, windows down or doors open.

I'm sure there's plenty more that I'm missing so it'd be worth searching up the basics on an A/C forum before you actually begin the process.

Good luck.

 

Why it's not that difficult to get too. Unless your refrigerant is leaking that fast I advise about modifying that compartment.

But if you must sell yours and buy one that's been beat up to modify. They are costly parts

 

I just did this today on a 97 355.

Pictures of charging port and location. I was only able to get right to the green range but not solidly in it with 1.5 cans of AC Pro.

I know I have a freon leak at the compressor that I have observed on the lift. I'll take care of that this winter. In the meantime the AC works for now.
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I highly recommend a set of gauges, you can pick some up from amazon for under 50bux. The low side pressure barely tells a even a small part of the story, you need both for anything close to a proper charge.

 

Not a job to tackle yourself if u have not worked on AC before, too much gas is as bad as too little. Not as easy as u might think

 

Thanks for the pictures DrBob. I took my car out for the first time in several weeks, and the A/C just wasn't touching the heat we are having! Time to put the gauges on and see what the problem is. Hopefully it is just low on 134a.

Every time I park my car for several weeks, it punishes me.

 

Just a handful of phillips screws hold the trunk liner in place. You'll spend a lot more time mutilating it than just taking it out/in a couple times.

 

Hi Ernest. Glad it helped. As I said I'm fairly sure I have a seal issue on the compressor but I really don't need or use the AC very much so not a high priority but I will get it fixed properly someday.

 

Bob,

Just a thanks for posting the pictures on this thread in 2016. I have to add some 134 to mine and immediately found the Dryer but the charging ports were a mystery.