Hi everyone,

Can someone tell me which is the LOW valve on the W163? Unfortunately, MB does not label the valve caps with "L" or "H"....unlike other makes.

My guess is the valve next to the driver-side headlights (behind the front grill) is the LOW "L".......and the other valve is near the pass-side coolant (fronting the firewall) is the HIGH "H".

Am I correct?

Thanks in advance.

Pete

Look at the diameter of the a/c lines , the larger diameter line is the low side .

How much experience do you have with a/c ?
Depends on the location of the service ports is enough information to know which is the high or low pressure side.Also the fittings are different size .

Thanks...I thought so...so its the one up front.

Not much experience...I'd like to think this is a DIY type of job....already done the recharging on my other 2 vehicles.

Normally, the low or suction side will be cold to the touch also - unless you're way low or out of freon. Then you have a leak somewhere that is going to have to be fixed. If you don't purge some freon through the line you're using to charge the system with first - with the system not running - you will suck air into the system with the result being contaminated freon and an inefficient cooling system. Since you've done this before you probably already knew that.

I'm having same problem with my 2006 ML350. the valves aren't marked L or H.
Anyone can help out??

You are on the wrong forum. You should be on the W164 forum.

https://mbworld.org/forums/m-class-w164-72/

But here are the locations of the low and high side charging ports on a W163, and they could be similar.