This is on a 2008 G35S

Remove the Brake Fluid plastic door on the driver side. It will reveal the brake fluid reservoir and master cylinder.



After starting the vehicle and turning the A/C to MAX. Remove the L cap and secure the Freon bottle/gauge to it. DO NOT USE THE H VALVE.



This is a very easy project but I was unable to find anything on the board by searching where the Low pressure valve was located.

 

Thanks for the post.

How often we need to do that??

 

I really hope you didnt try to put Freon in your AC system, since it uses R134a refridgerant.

 

Proper way.

You need a temperature measuring tool- like a thermocouple or a temperature readout like sold in Harbor Freight Tool, or similar (like 5 or 10 dollars). Measure the temperature of the outside air. Write it down. Then put the temperature sensor in the cold air outlet by the drivers door. Close the door. Turn on the engine, put the AC on recirc, 60 degrees, maximum fan speed. Hook up the gauge and the can of R-134a. There is a chart (usually on the can of refrigerant) to tell you how to set the gauge indicator on the can based on the temperature of the OUTSIDE air that you wrote down.

The inlet pressure depends in part on the temperature of the air- in the winter the inlet pressure will be low, like 25-30 psi if everything is OK. In the summer, at 85 or 90F, it will be in the range of 45-50 psi, maybe 55psi at the most. This is OK.

The compressor can only stand so much differential pressure, so do not run above about 50-55psi- this may cause the compressor to "lock".

While the AC is running, open the valve and let some fluid into the inlet port. The pressure may rise to ~60 psi, just close the valve a bit to bring it into the correct range on the gauge. Repeat until the pressure sits in the indicator range. The outlet temperature in the driver's side vent in the car should be about 40-42F when the system is stable, doors closed and recirculating the air. DO NOT try to get it colder- this is about the limit for an open loop cooling system- about 40 degrees difference between outside and inside temperatures.

 

Well you know what I mean. Freon / Refrigerant... calm down Adolf.



It is not an often maintenance item, but since I recently bought the car and it was 105 degrees in Dallas yesterday I thought it would be a good day to check the levels.