Vrodman

Is it possible to overcharge the AC system such that when the pressure in the system is too high the compressor won't kick on? Everyone knows the other scenario when charge is low, pressure therefore low, the compressor won't kick on, but it seems I may have the first situation going on here. I'm guessing this because I had the system serviced by steeler about a year ago and they assured me that the system was fine and charged. But on hotter days the compressor wouldn't engage. I had another shop verify that charge was OK and possibly even slightly overcharged. As a mechanical engineer, and going back to basic thermodynamics, I'm thinking if it were overcharged, on hot days the system pressure would rise even higher possibly reaching some compressor shut-off threshold. If the system were undercharged, I would expect it behave in the opposite manner. As in not kick on in cooler weather.

So I'm thinking I should look into this a little closer personally, since I don't much trust dealers and most shops. Is there a sight window in the W210 somewhere under the hood to see charge level as in other cars? Where exactly is it?

Anyone else have any weird AC issues like this that can shed any light on it?

Please help as it's getting hotter than

Thanks

Yacht Master

Everything you wanted to know About A/C but were afraid to ask.

http://www.eclassbenz.com/node/27

Vrodman

Yacht Master, Thanks a Ton! Way Cool website.

Cheers

Vrodman

After checking out the website that Yacht Master suggested, it looks like I may actually have low refrigerant! This is exactly why I don't trust steelers and most shops! (See Above) So what is a reasonable price to pay on average to charge an AC system these days? Before I call up a couple of shops, I want to have some kind of baseline.

Thanks in advance

Yacht Master

That can be an easy DIY, most discount stores in the US sell R-134a refrigerant. I would suggest the 1.5 LB can with a pressure gage on it.
Retail price should be $27 to $35 It is a pretty easy operation.

Few questions and info. How long did it take for your charge to be come marginal from full charge?
Depending on the rate of loss you can determine need of repairs. Generally speaking no leak is what we are after, and any loss that requires a recharge in less than a year should be fully leak tested, and necessary repairs made.

Vrodman

After double checking, it's actually been about a year and a half since I had it charged. So prolly doesn't have too bad of a leak when you consider the EC light doesn't stay on and the AC still actually works about half of the time. Although, it's definetely not getting as cool as it once did.

So I didn't realize this was a DIY candidate. Back in the day there was no such thing unless you had all the right equipment and then did it illegaly. I guess it makes sense with the new "environment friendly" refrigerant that it could be DIY. Shops certainly don't want us to know this do they

So with all that said, can you steer me to a link or explain where the connection valve is and what the exact process is? Would this be on the link you gave above? (I'll check there in the meantime until I hear back from you)

Thanks Again Yacht Master for your tips.

Yacht Master

A year and half sounds good. I would make notes to keep with car records regarding all the diagnostics readings before and after recharge and the date the recharge was done.
The can of R134a will have instructions on it, try to find one with a gage too.
Basic process, start car and set AC controls to max cool.
I wear gloves to protect my hands in case, during hook up and removal of hose any leaking refrigerant from connector won't give me frost bite on my hands.
Remove cap on charge port and attach hose from can of R134a.
Pull trigger on can, watch charge indicator on can, this can take what seems like a long time 5 to 15 minutes.
During this process you should check to see if your compressor is running (engaged) when charge is low it may take time for system to reach a pressure sufficient to allow compressor to start. Then check the temperature of the air discharged by your AC inside of the car it should be producing cooler and cooler air as the charge nears a full indication, on the cans gage.
When the charge is done remove the hose replace the cap then do the diagnostics again and make note of the readings.

Be safe, always wear eye protection and stay clear of belts.


You may want to look through the stickies for additional information
Good luck.
YM

Vrodman

Yacht Master, Thanks a lot. Nice pic and graphic. That W211 motor looks a lot cooler that my W210. I've been thinking about upgrading to the W211 for a while, but I think I'll wait a year or two to see what W212 has to offer. If nothing else the W212 will possibly bring down the W211 used pricing. I bought my 210 new, but I might not go the new route next time just out of cost effectiveness.

Thanks again for your help. I'll be jumping on this project today.

Yacht Master

That is my E430 sport motor, first cousin to W210 E55, less 75 hp.
The W211s E55s are depreciating at approx $1k a month.

Vrodman

Oops! I haven't actually seen under the hood of the W211 and assumed because you have a W211 that that was what the pic was. I also han't ever looked at an E430 under the hood before, although I'm very familiar with the E-class line 320, 430, 55, and now 63. On my initial quick glance of the pic I thought the different engine cover was for the superchargers. Anyway, now that I've tried to explain my blunder , I'll update you and anyone else interested on the AC issue:

I purchased an 18 oz can (the biggest Kragen had) with charging tube and gage on it. It was actually on sale for $19.99 because they were pushing a newer model that simply had the gage on top of the can instead of in-line with the tube. The sale version was $12 cheaper. Talk about a "no brainer" Anyway, I was able to successfully charge the system! It gets WAY cold now and no more annoying hissing sounds coming from the vents! One word of advise for anybody that needs to do this would be to buy the pull-lever style charging can instead of the push button style. I'm 6'2" 215lbs and do a lot of power-lifting at the gym and that D*mn button was taking two hands! (and the charging process can take 5 to 10 minutes) I can clearly see why they came out with the lever design!

Thanks again Yacht Master for the tips and the great pic.

Cheers

hafabd0

So, what are you guys saying? Is the K&N filter good for the E55? Improve performance but it might get the MAF dirty sooner than the stock filter would? Let me know before I make the purchase. Thanks for the advise.

Vrodman

Just one man's opinion here, but the K&N filter technology is archaic. I don't believe you realistically gain any significant Hp from using them. I have used them in the past on other cars and found this to be the case. When you add this to the shortening of the MAF life, it doesn't seem to be the best way to go. You should see the thread "Non K&N Air Filter Question" This really isn't the best thread for this question. Good luck.