How to Recharge Air Conditioner ML320 W163 1998-2005

How to recharge the Air Conditioner (A/C) system of your ML-Class W163.

Applicable to ML320 ML350 ML430 ML500 ML55 AMG 1998-2005

Before we begin, remember: These instructions may vary depending on the AC recharge kit that you are using. Be sure to always read the instruction notes on your recharging kit.

Turn the engine on and let it idle. Turn the air conditioner ON and set it to the maximum cold setting.
Open the hood of your ML320 W163 and locate the low-pressure AC service port and remove the cap.
Attach the refrigerant gauge to the service port. You will need to press and hold the quick-release at the end of the hose, insert it on the AC charging port then release it.
Read the pressure in your air conditioner system. If the pressure is low the gauge reading will be in the white zone. If the pressure is normal then the gauge should be in the green zone. You should not have a reading on the HIGH / RED zone except when the car is turned off, in which case it is normal.
Always keep the can UPRIGHT. As you charge the system shake the can slightly every two or three seconds while you are charging.
Every 30 seconds release the trigger to stop the charging process and read the pressure. Make sure it is not on the RED zone.
Stop recharging the system when the pressure gauge shows normal, in our case, it should be in the middle of the green zone.
Detach the connector from the low-pressure AC port. Reinstall the cap, close the hood, and enjoy your AC system again.
THANKS FOR VISITING MERCEDES MEDIC.

What is the best A/C recharging R134a kit to use?

It’s up to you to choose the recharging kit of your preference. There are many A/C recharging kits available but as you make your selection there are a few things that you should keep in mind. Things to look at when you make the selection are:

Does the R134 refrigernat have any oil added?

Does it have dye to help you find leaks if the system doesn’t hold pressure?

Does it have any leak sealer?

	A/C PRO ACP-100 Professional Formula R-134a Ultra Synthetic Air Conditioning Refrigerant with Reusable Dispenser and Gauge – 20 oz This kit has a gauge for the outside temperature adjustment. You can know the exact pressure range you need to be in.
	Interdynamics MAC-134 EZ Chill Refrigerant Refill with Charging Hose and Gauge – 18 oz A/C refrigerant has oil and leak sealer mixed in.

Important Notes

DO NOT TURN THE CAN UPSIDE DOWN WHILE CHARGING. Only gas should go into the AC system, by turning the can upside down the AC system will get liquid refrigerant which can cause the AC compressor to lock up and also wash out the oil. Keep the AC refrigerant can in the up position and only shake it slightly while charging.
If the refrigerant level is very low, the AC compressor will not engage. Charge the AC system for a couple of minutes with the engine running, and you should notice the AC compressor engage/kick in once you add enough refrigerant into the system.
If your gauge is not working correctly, it’s probably because your compressor is not spinning. The AC compressor stops spinning when it’s low on refrigerant. Add some refrigerant until the AC compressor kick in, to get a pressure reading.

Where is the A/C charging port located?

The A/C charging port on your ML W163 is located on the passenger side of the firewall. Look near the battery and the coolant expansion tank. You will see the A/C line and the black plastic cap on top of the A/C low-pressure line port.