susemu

Hi,

my a/c stopped working due to low R134a. The EC button is lit. I got the system refilled by a local mechanic and now I need to find out how to reset the a/c as to make the compressor turn on again.
Anybody having some ideas?

Thanks in advance.

Glyn M Ruck

It should come alive all on it's own if you have correct refrigerant pressure. The system has a refrigerant pressure switch to protect the compressor.

You can try a controller reset

https://mbworld.org/forums/c-class-w...tic+easter+egg

e24kgold

At least in the w210, when the ec is on you must do the reset before the compressor will kick back on. The ec light is activated (compressor off) to prevent damage. Im sure the procedure is somewhat the same on the R-class. check out the R-class forum or the w210 for more info.

susemu

Darn,

sorry guys - I forgot to say it is for my 2002 C230K - not the R.

e24kgold

I not sure on the c-class contact your indy or mb dealer

fanito

+1, had the same issue, added the refrigerant and that was it. The diag procedure is spot on... press recirc and defrost at the same time then start your car, hold for 5-10 secs until it blinks, should run for 30 seconds or so. Also it calibrates the stepper motors which is a plus.

susemu

Thanks for the tips - but no go so far. I did the diag procedure and it took about 30 seconds until it was finished. But the compressor still does not turn on ...

mleskovar

How are you determining that the compressor "does not turn on"? Did you ever get the EC light to go out? (I'm no A/C expert).

susemu

Well, the compressor is actually running but not creating pressure according to my mechanic. The light is still lit.
I'll drive around for a few more days and then I wilh have to bite the bullet and bring it to the dealer.

b87lar

Sorry if this response will be disappointing - I had the same problem on my 2002 c230 coup and no fiddling with buttons would get the ac/rest unstuck, and local shop had the qeuipment necessary to reset it. I paid 1hr labor ($100) at the dealership for them to reset that light.

Glyn M Ruck

The A/c should not need readaption but who knows

Does your circuit look like this & does the low & high side read correctly?

b87lar

The reason why the AC/REST light needs to be reset first is that you cannot recharge the system while the compressor is turned off, and the compressor is off as long as the AC/REST block is in place. There is no way the system will unblock itself automatically (or magically)

Glyn M Ruck

Not true - done it many times. I should point out that there were changes made to the W203 a/c system & you might be correct on very early cars - not on newer ones.

amanonfire

The Rest light is on in my 2003 C230, yet the system is showing adequate pressure with a gauge hooked up to the low side. The reset procedure did not cause the Rest light to go out, so looks like I'm off to a shop to see what's up.

Glyn M Ruck

Please let us know what you find. Your car like mine has the unintuitive light on = a/c off - yes? Newer cars are the reverse. Cars I have worked on have always come alive with correct refrigeration pressure as long as no other fault existed. I would like to establish whether this is MY dependent.

Glyn M Ruck

Kindly posted by splinter on another thread. As you can see there is a potential reset/recode to be done.

mskembo

I did this last night since my A/C had been acting a little squirrly recently. It worked!

pejaife

What did you do?Did you just recharge and a/c came alive on it's own with correct pressure or did you do a controller reset?If you did controller reset, then how?

I had done a recharge with correct pressure without luck.

phister

believe mike did the reset that Glyn posted in the second post

pejaife

I tried it and did'nt work.Kept flashing for half hour.By the way i have analog temp controls.

t4pizza

I have a 2003 C230 sedan, did the procedure and it went through a diagnosis which was evident by the blowing of air through different vents. The bad part was that it did not unlock the red light that indicates the a/c is off. Is a trip to the dealership the only way to unlock this? A few weekends ago I used a vacumn to empty the system and attempted to recharge but could barely get any gas into the system without the pressure getting too high. I figured this light being on was somehow preventing me from recharging the system. Really hoping there is a diy as I hate the dealerships prices. Thanks