sanjivsai

Dear All,

I have a 1999 CLK 230k (automatic climate control). The problem is that no matter what position the blower is in (temp on min, fan on high or low and ECO button pushed) only hot air comes out. I have had the vehilce re-gassed, but the problem persists.

Can any one advise me on this issue?

Thank you for your help.

Regards


Sanjiv

shandy2550

The default setting on the heating water control valves(duovalve) is fully open so it may be that electrical power is not getting to the valves, check your climate control fuses in the main fusebox under the hood ,also check the power plug to the valves. See here for location;http://mbclub.co.uk/forums/showthread.php?t=26888 .
Geo.

sanjivsai

Thank you for your reply.

I have checked all the fuses for both the Automatic Air Conditioning and Blower and these are fine. I have also pushed the ECO button in and out, no change.

Any other advice - could it be the Fan regulator, which is faulty?

shandy2550

The fan regulator has nothing to do with the temperature of the air coming out, just the volume.
Don't have a guide for your car but this may help,it's for the W210 E-class.
http://mb.braingears.com/W210/w210/climcontrol.htm.

MBTech21

Is the compressor running? If it is- the first place to start is with a check of the system pressures.

sanjivsai

I have had the A/C system checked for both pressures and leaks and it is free from these.

I have not checked the compressor - What is the best way to do this?

I have checked all the fuses in respect of both the Automatic Climate Control and Blower and these are fine.

I have also held the "rest" button down on the Climate Control Module (N22) for 6 sec and it indicates a value of 1 on the leftside and upwards of 19 on the rightside - Does this signify anything.

Pegasvs

Hi there.

When you switch on your a/c you should know if the a/c compressor switches on as the engine noises changes and the revs drop.
I think the fault is that the flap that regulates how much hot/cold air to let in the mixture is not turning. This could be a fault of the other compressor that supplys that flap with air.

soldierbenz

I have a CLK 430, just got the A/C charged today. It was a pound low on 134a.

Here is the catch, the car blows awesome on the first 3 fan settings. The compressor cycles in and out.

When you put the fan on high, it quits blowing cold and becomes warm. Can anyone tell me what the heck is the problem?

I would apprecited any input. Thanks

Soldierbenz

MBTech21

OK....a little AC lesson- the pressures mean something- not just that it is full. When the compressor is running and the rest of the system is working right, the refrigerant goes through 4 changes of state to move heat energy form the inside of the car to the outside (energy can not be destroyed, only moved) .

A proper running system (R134a) should have 2.5-3 times under hood temp on the high side for pressure (225-300) and the low side should be 35-50. To give you an example- a stuck expansion valve will give you a high side about normal and a low side in vacuum. A none functional compressor will give you the same readings on both sides (about equal to ambient tempature). Etc..Etc.. Thats why this is critical for these diagnosises over the internet..throwing sensors, etc at things will not help if all this isn;t in order..

MBTech21

That other compressor is the engine...the PSE helps, but only under no engine vacuum conditions (ie: hard accel/WOT)

MBTech21

With the temps around here lately, it should be running almost continuously. How often is it cycling off?

soldierbenz

I had the system evac'd and recharged today and there was no leaks. They put about 3lbs of 134a in the system.

It blows good on the first 3 fan settings, but once I turn it on max it gets warm in about 10-15 seconds.

When I turn the fan back down, it doesn't get cold again. I have to turn the control off, turn off the car, start it back up and then turn the control back on low.

This is really nerve racking.....

sanjivsai

Thank you all for your help.

More Info:-
The position is that sometimes when I put the A/C module settings on LO - sometimes, there is no change in sound (i.e. nothing or one will notice a change in sound and cool air will enter through the central vents for a time and then turn to hot).
Therefore does this mean that the blower motor regulator may be failing or has the A/C compressor failed.

MBTech21

My guess would be the evaporator tempature sensor- it will try to stop the evaporator from freezing up. Very common problem

soldierbenz

Do I have to have the system discharged to change this and do you know where I may find the part? I went home last night and checked the temperature on the 4th fan settings, it was 45 degrees.

I asked another question on another post, sure you can answer it also. It was on the Service Eng Soon light. I read in the owners manual how to reset it.

After turning the key in position 2 and holding the "0" button for 10 sec the miles come up.

Mine says; 4.3 on top and 030000 on the bottom. I can't change these numbers or reset the light. How do I do that?

soldierbenz

Where exactly is this located? You've been very helpful!

MBTech21

It is inserted in the driver's side of the heater box. You can get to it by removing the under dash panel. It has a two wire connector. I can't get the pictures off my Startekinfo to copy for some reason..Sorry..

soldierbenz

Thanks MB!!! If you happen to get the pics, I would appreciate them or the link. Thanks again!!!

soldierbenz

MB,

Your the .... I fixed it last night. My A/C blows about 44 degrees, on all settings. I changed the evap temp sensore and everything worked. I appreciated your help.

I called my local MB dealer ship, it was $55 for the part and $90 to change it. It took about 35-45 minutes to change it myself, and I had to hunt for under the dash. Thanks again,

CoolHandz

Hi Guys,
What a very informative forum just wondering if you guys can help me with my A/C problem as well.I just charged up my unit so I know it's full I'm I'm in SanFrancisco so we really rarely use our A/C here but I decided to drive to Vegas over the weekend and there i noticed the same problem.When the outside temp is below 100 my A/C blows cold air up to level 3 but if I fully blast the A/C it blows hot air.It does this even if i lower or re-set.Could this be the temp.sensor problem?If it is can you tell me where it is located on my truck.Also I observ my A/C motor at full blast to be engaging and disengaging as if it's getting out from stop to go rotation.Oh Guess what happened when I got to Death Valley with 120temp.
Thanks

MBTech21

Are your aux. fans coming on? The fuse and or relay blowing are very common on them.

CoolHandz

Yes both Fans are working infact the aircond.works until you crank it up.Blows cold air on 1-2 starts blowing warmer on 3-4.Bad part is when it really gets hot after driving an hour if you full blast it will not blow out cold air just regular outside air.I checked the compressor at idle under full fan it turns and stop as if you are turning it on and off.Do you think I have a bad compressor or a sensor?

MBTech21

what year is it??

CoolHandz

My truck is a 99 ML 430 sorry I forgot to mention that.