C230 AC Clutch won't engage
 

Brought the car into an AC shop to fill with freon and/or find leaks. They said they filled it but the clutch wouldn't engage (it did when I brought it there). I checked the clutch and I checked the codes and they all seem ok, including the low pressure. I put a little air pressure into the system untill the pressure code didn't say low and checked the signel going to the clutch and it's at about a tenth of a volt. What else can I check or what else could it be.

What Year car??

There are several different system depending on the year, some don't have clutches.

1998
 

It does have a clutch, and I checked it, disconnected it and put power to it and it engaged, and it measured appropriate resistance, and it worked when I brought it in to the AC shop.

On a 1998 the a/c pushbutton sends 12V directly to the clutch.

Have you looked at actual sensor values thru the controller?

You mean reading the codes? Yes, I have and they all seem ok.

I also disconnected the clutch and put 12 volts directly on it and it engeged.

2000 same problem
 

Any ideas? Power not being sent from head unit?

I measured it and gave it all the right conditions to engage the clutch and it didn't. I hate to buy a climate control just on the information I have. Is there anything else I can do to tell what the problem is to justify buying anything?

In the actual value screen, does the evaporator temp sensor have a good reading?

Also is the refrigerant pressure reading in spec, between 3-25 bar?

The evaporator temperature has a good reading now. I didn't (149) and replaced the sensor and its ok now.

As far as the pressure goes, I can only assume when the AC shop filled it that it was good. I put about 1.5 bar of compressed air into it to get it off its "lo" reading but it didn't engage and I was concerned about putting more in. Would you suggest putting 3 bars of compressed air in and seeing what happens?