Let me start by saying I have seen the many threads on MB HVAC fans failing due to corrosion from water drips caused by clogged vent drains ...
We have a 2009 ML350 Base model with about 85K miles. It's had odd AC problems that we've been trying to tackle. I'm sharing some background leading to our current fan troubles in case it's helpful.
First, the compressor would stop cooling intermittently, at first for only a couple of minutes at a time but then worse. It would sometimes go days at a time working fine, and then days at a time not working at all. A local ac shop wanted to replace the whole compressor and pipes for $1300 or so, but we felt the compressor must not be the issue or it would never work.
We first tried replacing the Climate Control panel on the dash with a used one found on Ebay. Zero change -- so if it was the problem, then the replacement was defective in exactly the same way. We then replaced the AC Compressor Solenoid with a new one. Voila, this seemed to solve the problem. All was good and we enjoyed a few days of bliss.
But then, a new problem emerged: On longer drives, the blower fan would cut out after 45 minutes or so of use, especially highway use. It would often come back on if we stopped and turned the ignition off and back on. Sometimes it would come back on if we simply stopped at a red light. We thought this might be the result of overheated circuits having had a chance to cool off.
I read about the issue with corrosion on the blower motor. I took it out to try cleaning it, and while there was a bit of rust on the nut holding the fan in place, there was no corrosion visible on the circuit board or any connectors. I did some gentle cleaning with cotton swabs and isopropyl alcohol anyway. Zero change.
So, I ordered a replacement fan on Ebay. It was a new fan, but not OEM. (The original was made by Valeo, the replacement seems to have no brand markings -- BUT it seems better engineered to cope with potential rainwater leaks because the fan has a solid cone that would deflect them, and the motor housing has a drain hole.)
The new fan's air flow perhaps seemed more robust ... but the same problem persists, with it cutting out after 45-50 minutes of heavy use.
I saw one thread where a poster found that the plug on the climate control was loose, and clicking it more solidly into place solved the problem. I don't believe that's the problem, because I'm pretty certain I clicked it in place when I tried switching the panel in the beginning -- but something like this is interesting given that the fan will sometimes randomly re-engage if you stop the car. I intend to at least give it a shot.
Has anyone else experienced (and hopefully solved) this? Any ideas? Thank you in advance ...
We have a 2009 ML350 Base model with about 85K miles. It's had odd AC problems that we've been trying to tackle. I'm sharing some background leading to our current fan troubles in case it's helpful.
First, the compressor would stop cooling intermittently, at first for only a couple of minutes at a time but then worse. It would sometimes go days at a time working fine, and then days at a time not working at all. A local ac shop wanted to replace the whole compressor and pipes for $1300 or so, but we felt the compressor must not be the issue or it would never work.
We first tried replacing the Climate Control panel on the dash with a used one found on Ebay. Zero change -- so if it was the problem, then the replacement was defective in exactly the same way. We then replaced the AC Compressor Solenoid with a new one. Voila, this seemed to solve the problem. All was good and we enjoyed a few days of bliss.
But then, a new problem emerged: On longer drives, the blower fan would cut out after 45 minutes or so of use, especially highway use. It would often come back on if we stopped and turned the ignition off and back on. Sometimes it would come back on if we simply stopped at a red light. We thought this might be the result of overheated circuits having had a chance to cool off.
I read about the issue with corrosion on the blower motor. I took it out to try cleaning it, and while there was a bit of rust on the nut holding the fan in place, there was no corrosion visible on the circuit board or any connectors. I did some gentle cleaning with cotton swabs and isopropyl alcohol anyway. Zero change.
So, I ordered a replacement fan on Ebay. It was a new fan, but not OEM. (The original was made by Valeo, the replacement seems to have no brand markings -- BUT it seems better engineered to cope with potential rainwater leaks because the fan has a solid cone that would deflect them, and the motor housing has a drain hole.)
The new fan's air flow perhaps seemed more robust ... but the same problem persists, with it cutting out after 45-50 minutes of heavy use.
I saw one thread where a poster found that the plug on the climate control was loose, and clicking it more solidly into place solved the problem. I don't believe that's the problem, because I'm pretty certain I clicked it in place when I tried switching the panel in the beginning -- but something like this is interesting given that the fan will sometimes randomly re-engage if you stop the car. I intend to at least give it a shot.
Has anyone else experienced (and hopefully solved) this? Any ideas? Thank you in advance ...