Which one is the low pressure valve? the one on the thinner pipe?

low presure AC port could be under the front wing like a ford focus on the drier canister but some renaults do not have one they only have one filler point with a large valve so you think it only has a high pressure port but in reality its the low pressure with the big valve so you swop the pipes around the AC machine ,look to see if this pipe is going to the low pressure side of the pump its a thicker pipe is the clue .

during the 1995 R12 was still in uses if you have 134a then you have the conversion here are the valve rule of thumb if the A/C pipes are thick you have the low pressure line the filter drier is a low pressure area, here the high pressure the condensor the thin line is the high pressure, go to the filter drier follow the thick line and you will find a valve that low pressure, go to the condensor the thin line you may even find a sight glass that area is the high pressure you should find a valve this is the high pressure

THE LOW PRESSURE LINE IS ALMOST ALWAYS LOCATED ON THE WIDER PIPE OF THE 2 AND SOMETIMES THEY HIDE IT UNDER THE AIR CLEANER ASSEMBLY.

The low pressure side of the r134a system is always located on the thicker pipes vs. the thinner pipes leading away from the compressor.

So, just followi the larger diameter piping from the compressor until you come to a quick connect fitting that attaches to the hose quick connector that is attached to a can of r134a.

The pressure reading should be 25 psi to 45 psi on the low side when the compressor is turning and the a/c is on.

If it's higher than this, the compressor may not be turning, and the normal non turning psi is 75psi to 100 psi or so on a hot day.

A/C low side ports are located on the 'thicker' plumbing vs. the 'thinner' plumbing coming off of the compressor.

Just follow the low side pipes from the compressor to the first low side port. It should also fit a quick connector onthe hose/can combination for r134a. The high pressure side port will not work with the low side hose quick connector.

Hope this helps.

The a/c has a low pressure port on the low pressure side of the a/c piping system.

One can identify the low side by looking at the 'thicker' pipes vs. the 'thinner' pipes on the high pressure side.

There may be a canister that has a low pressure port on it on the passenger side. Or else, it's on the thicker piping itself.

There may be a blue or black cap on the port.

The pressure should read 35psi to 45 psi on the low side when the a/c clutch is spinning or engaged.

When the a/c clutch is not spinning or engaged then the pressure should read 75 psi to 100 psi on a hot day.

All you need to do is to trace the thicker piping of freon from the compressor to the low side port. The thinner piping is the high pressure side.

Add freon on the low side port:

The low side port is located on the thicker piping vs. the thinner piping.
It may have a black or blue cap.
The hose, don't worry' won't fit anything but this quick connector,

follow the thicker pipes vs. the thinner pipes to find the low pressure side fitting. It might have a blue or black screw on plastic protective cap with an o-ring.

The charge kit will have a tube that has an end that fits only the low side quick connect pressure fitting.

Good luck getting colder air conditioning!

the low pressure is the wider pipe.