A/C Pressure

[steve1]

I know this may be a silly question, but if you have too much pressure/fluid in your system, what is the best way to relieve some of it, recently had mine re-charged, and ever since it's been playing up, so I think they may have over filled it.
I know I can go back and ask them to do it, but if I can do it myself then it saves a lot of time and effort getting the car back to them.

Steve.

[AMG Merc]

Not sure - isn't there a fluid indicator (sight glass?) or something similar?

[JLSELAN]

There is no sight glass, unfortunately.
I suspect your A/C service center will have to hook up their equipment to safely change the amount of refrigerant in your system.
BTW, that brings up another question. Here in the U.S. the recommended maximum amount of refrigerant to fill the A/C system (after it has been totally emptied and dried out) is 1.4-1.6 lbs ( 0.64-.073 kg). Our systems work well with that charge amount, even though it's quite a bit less refrigerant than the 0.95-1.0 kg charge levels posted on the wiki. Does anyone know why there is such a big discrepancy?

Edited by JLSELAN on Saturday 19th April 17:38

[ThatPhilBrettGuy]

JLSELAN said:

Here in the U.S. the recommended maximum amount of refrigerant to fill the A/C system (after it has been totally emptied and dried out) is 1.4-1.6 lbs ( 0.64-.073 kg). Our systems work well with that charge amount, even though it's quite a bit less refrigerant than the 0.95-1.0 kg charge levels posted on the wiki. Does anyone know why there is such a big discrepancy?

Same refrigerant as in the UK?

[JLSELAN]

Not sure, but AFAIK any environmentally acceptable alternative to Freon 12 (the banned refrigerant) should have pretty much the same physical properties.

[F.C.]

Possibly a different air con system as UK system does have a sight glass on top of the dryer unit.
F.C.

[JLSELAN]

That's interesting since AFAIK, again, none of the U.S. cars have a sight glass. Might also be an age and/or model thing, since U.S. cars (total of 220) were only produced between 2003 and 2007 and only in two models -- 3R and M400.

[F.C.]

My car is 2005 M400.
F.C.

[rort1]

For those with a sight glass - is it the fish eye thingy on top of unit in front n/s wheel well? If yes, how do you read it - I can see a brass outer and dark brown inner in the glass but have absolutely no idea if this means full or empty - help for the a/c numpties greatly appreciated!!

[AMG Merc]

rort1 said:

For those with a sight glass - is it the fish eye thingy on top of unit in front n/s wheel well? If yes, how do you read it - I can see a brass outer and dark brown inner in the glass but have absolutely no idea if this means full or empty - help for the a/c numpties greatly appreciated!!

Not absolutely sure but I think you look for an air bubble dead centre of the glass meaning all's well.

[JLSELAN]

AMG Merc said:

rort1 said:

For those with a sight glass - is it the fish eye thingy on top of unit in front n/s wheel well? If yes, how do you read it - I can see a brass outer and dark brown inner in the glass but have absolutely no idea if this means full or empty - help for the a/c numpties greatly appreciated!!

Not absolutely sure but I think you look for an air bubble dead centre of the glass meaning all's well.

Well, almost--with the engine running and the A/C compressor operating, there should be no bubbles in the fluid moving through the system that is visible in the sight class. You will only see bubbles if there is air in the system, and that is not good for cooling efficiency.

[Adrian W]

AMG Merc said:

Not absolutely sure but I think you look for an air bubble dead centre of the glass meaning all's well.

No Rob that's a spirit level!






Bloody marketing people

Edited by Adrian W on Sunday 20th April 20:14

[joust]

Remember that the sight glass is normally covered up with a piece of sticky back paper, and so may need to be pulled off before you can see it.

The glass should show solid fluid when the system is running.

Never release gas yourself into the atmosphere. It's nasty stuff for you near it and life in general and should (legally) be recovered if it has been overcharged. Take it back to where you got it done for it to be checked.

P.S. One way to check if the system is overfilled is that the compressor itself will be 'sweating' (i.e. like a cold coke can taken out in the warm air). However, as this compress is near the drive belt don't try playing around with touching it unless you'd like to loose your arm!

J

[AMG Merc]

Adrian W said:

AMG Merc said:

Not absolutely sure but I think you look for an air bubble dead centre of the glass meaning all's well.

No Rob that's a spirit level!






Bloody marketing people

Edited by Adrian W on Sunday 20th April 20:14

LOL and I thought I could use my Nob to put shelves up level Adrian!

I 'aven't got a buluddy clue and I'm buluddy fired!