MbNeedshelp

My 2001 S500 only blows warm air. Freon level is good, compressor clutch seems to be turning, all the A/C controls are working, plz help its way too hot in South Fl.

mercy-me

Try resetting your climate control by clearing the codes, see this video.............


Also, Brian Rice has done an excellent extensive write up on on the system. (See Page 18.)

Good luck,

Bob

MbNeedshelp

I did as the video instructed with no change. I will read the PDF carefully shortly, hopefully it will help me better understand the system and make the correct repairs. Thank you for your help.

cybertronicify

Since you are in Florida, you should have a left hand drive. Under the hood in the driver side. There are two silver pipes right next to the driver front strut nuts. Put your hand on the thick one and see if its cold, infact there should be condensation on it.

MbNeedshelp

no coldness at all. Does the compressor get 12v to engage the clutch? If so can I jump it to a 12v to test it ?

wallyp

There is no clutch - the compressor turns any time that the crankshaft is turning. It is controlled by an computer-controlled valve inside the compressor that causes the compressor to pump more or less refrigerant as required.

As said earlier, the low-pressure tube (larger one) should be cold, and the high-pressure tube (smaller one) should be hot. If not, some possibilities include:
- The computer has turned the system off. There is a tiny red light on the "AC" button. Red light ON means that the system is turned OFF. If this is the case, you must find and fix the problem, then reset the system.
- The compressor might have seized. You have to look very closely at the drive pulley on the front of the compressor. EVERYTHING on the drive pulley must turn together. Especially check the small bolt head in the center of the pulley.
- The refrigerant may be low. How did you check the refrigerant level? It is very, very difficult to check if the system is not operating.

cybertronicify

^^+1 I agree, these are variable compressors, it has a plate and 4 pistons. Sort of like variable valve timing.

MbNeedshelp

I hooked up A/C gauges and tried to add refrigerant but it wouldn't take any. I will look closer at the compressor to see if the center bolt is turning. There is a red light on the most right control buttons with the letters "EC". Is there a relay or fuse for system and if so would plz tell me where they are?
Thank you for helping !

wallyp

I think that "EC" on your car stands for "Economy", and the red light tells you that the AC compressor has been turned off by the computer (unless the light goes off when you push the button).

You aren't going to simply replace a fuse or relay and get the system working. You have to use a diagnostic system (either the built-in HVAC system or a STAR system) to see what the trouble code is, then fix the problem, then reset the system to clear the code.

There is a lot of info on the HVAC system in the encyclopedia ("start here" in the blue sticky area at the top of the page), in Brian's excellent write-up, and even on YouTube. At this stage, I don't think that any of us are going to be able to give you an easy, simple "magic answer".

Jack_88

Isn't there a self diagnostic you can run on the HVAC? I thought I stumbled on that being discussed at some point.

MbNeedshelp

Yes there is a self diagnostic , my bad I have just been clearing all codes. I will re-test and record the codes this time, and the red light doesn't go out by just pushing the button. Thank you. I appreciate ur help and patients .

MbNeedshelp

I ran a test, code came back faulting the high/low press switch. I pulled the press switch connector and checked for power. I'm getting 12v on one of the pins and abt 6v on the center pin and no voltage from the third pin. If the connector only had two pins I would simply use a jumper to see if the compressor would start pumping refrigerant . Is that an option here ?

kraut56

No, tread easy here.
can you turn off the red led in the AC switch?

If you cannot, that is explained in the WIS as an "unannunciated software error", which requires you to go deep into the AC control with DAS and erase the error.

Did it on mine and everything works fine (no freon needed).

Good luck!

m3j0n

cool to learn about the reset procedure. didn't know that.

MbNeedshelp

I have not repaired the A/C yet. but pushing the EC button does give me some fresh air when driving in the daily rains lately. I want to try eliminate all possible problems before taking it in to a shop. I was thinking of changing out the two press switches and re-charge the system and if that doesn't fix the problem I'll take it in to a Mercedes repair shop.

wallyp

If your system is like mine (2003 S430 USA), if the red light is set on the button, fixing the problem will not make the system work, nor will it turn the red light off. The system has to be reset...

MbNeedshelp

I had the system checked by MB Tech with the star program . I need to change out the expansion valve. Has anyone done that job before? Any tips on how to change it out would be appreciated .