Aussiesuede

I purchased a used R230 from a private party back in March. The vehicle was in pristine operating condition with the exception of 3 faults.

1. The rear defroster was inoperable

2. The Teleaid system was malfunctioning, and attempting to place phone calls all the time, thus draining the battery overnight.

3. The Air Conditioner did not function, and just had the blinking then solid AC-Off light illuminated


# 1 was fixed by replacing a relay
# 2 was fixed by completely removing the Command system, and TeleAid modules and installing a new stereo from the ground up.

I'd saved investigating the AC system for last because of the information given to me by the prior owner. He was the 2nd owner and purchased the vehicle at 60,000 miles and drove it for 6 years. He was a "Do Everything at the Dealer" kind of guy and had been told that the AC was malfunctioning due to a bad compressor. I took him at his word since that's what he'd been told by the dealer, and proceeded to negotiate a lower price to take into account the need for a new compressor and other possible foibles in the system.

This week I finally got around to purchasing an iCarsoft MBii Scanner. During my studying of the HVAC system, I'd discovered that the only way to reactivate the AC system that's stuck in the AC-Off mode is via scanner reset. And my SRS light was illuminated due to removing the Command and Teleaid system, so I knew the scanner would pay for itself after my solving those 2 issues. So I reset the SRS, and then scanned for codes on the AC system. There were 18 stored codes. A I rolled through the codes, I noticed that the oldest one was for low refrigerant. I found that one a little odd since I would have expected the low refrigerant code to come after some sort of failed hardware code?

The vehicle always had a slight squeak in the engine compartment from what I assumed to be a failing bearing in the AC Compressor due to being driven for 6 years with presumably no refrigerant and oil. But I noticed 2 things after having reset the HVAC when clearing all the fault codes. 1. The AC-Off light was no longer illuminated. 2. That squeak from the compressor disappeared after about 2 minutes. And for the first time since I've owned the vehicle, room temperature air was coming from the center vents.

After thinking about it for a bit, I thought - Could it really be as simple as low refrigerant? After 6 years of inoperation. My thought process went like this:

1) It's possible the dealership misdiagnosed the compressor issue since the previous owner was having expensive work done to the ABC system costing him thousands - and the dealer didn't want to pile on?

2) Since the HVAC system goes into sleep mode to prevent furthur damage, the compressor would no longer have the benefit of circulating oil in the system - hence the squeak and illuminates AC-Off lamp.

3) If #1 & #2 were indeed the case, then it would make sense that when I reset the system, the squeak might disappear due to some lubrication finally being reintroduced.

4) I decided to hook up the iCarsoft scanner again and check for new codes in the HVAC. Sure enough, there were 2 codes present, the 1st being for low refrigerant. But the AC-Off light wasn't illuminated.

5) To satisfy my curiosity, I took a trip down to the Auto Parts and picked up an 18oz can of refrigerant with a separated guage that I could reuse in the future. I hooked the guage to the Low pressure valve, turned the ac on full blast, and proceeded to discharge the entire cans contents.

*) The guage on the low pressure read right in the middle of the green. I reached inside the vehicle and put my hands over the center vent, and low and behold - ICE COLD FRIGID AIR!!!!!!

UNBELIEVABLE!!!!!

I let the vehicle run for about 10 minutes as I visually checked for hose/fittings leaks. Nothing seemed amiss. I went on a shakedown drive with the top up and the AC going full blast. I was shivering for the 1st time since owning this vehicle. During the 1st 10 minutes of the drive, the engine was running a bit rough at stop lights (a slight bogging). I suspect that it was the compressor working out crud from it's dormant state. After about 10 minutes, the roughness disappated, and over the past 3 days of driving, has completely disappeared.

So there you have it. An HVAC system that was diagnosed as having a bad compressor, is back from the dead with a simple recharge! I'd set aside $1200 for HVAC repairs, and it ended up costing me $19 (knock on wood). So those who have received a diagnosis of a bad compressor, reset your AC codes with a scanner, and do a simple $20 recharge 1st. You just too might get lucky and avoid the really expensive repair. Definitely worth $20 and 20 minutes of your time to find out if you too are lucky. Hopefully this helps someone!

pfarah77

That's fantastic news! I had a similar issue with an old Subaru which just required a can of 134A.

On another note: Would you recommend the iCarsoft scanner? Does it do everything (or almost) needed? Thanks and enjoy the chill!

Rudeney

Fantastic! One thing to watch out for is a slow leak. Often times, the seals shrink if refrigerant is not regularly circulated. The C240 had this issue and I;d have to charge it about twice a year. But i was fine spending $20/year on R134-A rather than hundreds on new parts.

Aussiesuede

Yes, I would definitely recommend the iCarsoft MBii scanner (As opposed to the i980 since the i980 doesn't give you the ability to deactivate the SBC brakes for safely changing pads). It's extremely easy to use, and gives access to Transmission, AC, Seats, HVAC, Airbag, SBC Brakes and Vario Roof ecu's. The ability to read and clear codes on these ECU's (And a few others) see's that the scanner pays for itself upon 1st use since the Dealer will generally charge $150 or more to perform any of those diagnoses. Be aware that it can only read and clear codes, but cannot perform adjustments on those ECU's. If you change your own brake pads, then it's handy to be able to safely shut down the calipers for safety sake. Also, if you decide to delete the Command system in favor of an aftermarket stereo, it's worth it's weight in gold to be able to reset the SRS light that will inevitably appear when any part of the Command is disconnected. (That said, for future searchers, if you completely remove the Teleaid module as I've done, then you still will need access to STAR to have the teleaid officially turned off since the part of the SRS system that automatically attempts to make an emergency call after the airbags deploy will still be looking for the TeleAid module everytime you start the vehicle, and when it doesn't find it, it'll light the SRS lamp)

Rudeney

Nice to know that the MBII model can de- and re- activate SBC.

Aussiesuede

Thanx for the headsup. I'll be keeping an eye on the HVAC system in the coming months, and I agree - even if a slow leak occurs, I've no problem doing periodic refills if necessary. Walmart has small canisters of R134a on sale for $4.88 at the moment - so I grabbed 4 just to put on the shelf since I now have an independent gauge and connector.

Aussiesuede

Yep, and for future searchers, it's worth noting that when you access the SBC ECU with the scanner, that simple action deactivates the SBC and you'll see the dreaded "SBC Inoperative Stop Vehicle and Immediately Visit Workshop" message and a press on the brake pedal will indeed show zero resistance as the pump has depressurised. Got my attention in a big hurry and it was a tense couple of minutes as I read codes for the system. Then as I exited the SBC menu, everything returned to normal. There is also a selection on the screen to officially disable SBC as well. Just wanted others to be alerted to the fact that the SBC message was normal even for simple Access to the SBC ECU.

Rudeney

More important then the SBC disable function is the re-enable. When doing this with SDS, it goes through some tests and runs a few charge/discharge cycles to set the distance of the brake pads to the rotors. If this isn't done when replacing the brakes, then the safety features of SBC may not work correctly, namely the ones that dry the pads when raining and move the pads closer when quickly lifting off the accelerator.

pfarah77

Thanks for the info!

alk247

How did I miss this thread? I am having AC issues from the moment I bought the car. At first there was a blinking red light when I tried to use the AC, then I recharged the system and after that the light is lit continuously when AC is on. I was sure that I need new compressor. While looking on line for the compressor I got a link to this topic. Next I am going to reset the system. It has never occurred to me that such step might be required.. Will report results upon completion.

Rudeney

FYI, we got a bit off-topic discussing the OP's scan tool and were talking about SBC (the brakes) ad not the ACC.

You should not need to reset anything on the ACC system just because it was low on refrigerant. However, investing in a scan tool that can read codes from the ACC and other systems is a good idea. It can give you codes that might help determine the problem.

alk247

If you reread the fist post in the thread, it clearly states that AC problem required clearing the AC system error codes.. I called that "reset".

danaw007

Rudeney

​
​​​​​I am a bit confused on that. In one sentence, the OP states he reset the system, but in another he states he just recharged it. I am not aware of anything in the ACC system that would require a reset if it were low on refrigerant. It has low and high pressure cut-offs, so if it's low, it will not engage the compressor, but once the pressure is at the proper level, that sensor should report it and allow the compressor to operate. I'll admit I've not done this on the R231, but I've worked on many other MBZ ACC systems and never needed to reset anything, even after replacing ACC components and recharging refrigerant.

Aussiesuede

For clarification, My experience was as follows:

I had 18 stored codes, so I'm uncertain if "any" code causes the system to need to be reset? Or if it were specifically one of those 17 codes other than the low refrigerant code? In my case, the HVAC system refused to resume normal operation until the codes were cleared.

I initially cleared the HVAC fault codes before attempting to add any refrigerant. Then the system extinguished the solid Red "AC Off" light. After about 2 minutes, the "AC Off" light returned to solid Red, since there still was no refrigerant in the system. I then purchased refrigerant and recharged the system and the following occurred:

It would engage the AC, then after about 30 seconds the "AC Off" light would blink continuously and AC would stop coming from the vents. If I then pressed the "AC Off" button, it would remain solid red and no AC would come from the vents. If I pressed the "AC Off" button again, the red light would extinuguish, AC would come from the vents, then after about 30 seconds, the Blinking "AC OFF" light would return and after about another 30-60? seconds the light would cease blinking and return to solid red with no AC coming from the vents. It wasn't until I cleared the codes again that the system returned to normal operation.

Here is a link that seems to shed a bit more light:

https://mbworld.org/forums/sl-class-...ult-codes.html


: AC System Reset

Rudeney

Thanks for that info. It does seem like some fault needed to be cleared for proper ACC operation. I guess this just continues to support the idea that if you are going to DIY on an R230, you need a proper diagnostic tool.

Frederick NL

Aussiesuede

Yes the MBII reads Vario Roof Faults

No, I do not believe it's capable of reactivating the seatbelt warning.

850csi

Does anyone have any suggestions as to which kit is best for our cars (M113)? Seems pretty straightforward?