Why Is My Air Recirculation Switch Blinking? - Benzworld.org - Mercedes-Benz Discussion Forum

500MPL · 03-20-2007, 09:49 PM

This is the second time this has ever happened to my 560SEL. With the ACC set to Economy and the fan on low, all of a sudden the Recirculation Switch started blinking repeatedly while the system went to a heat mode.

The temp is at 67F. and the system reset when I stopped and turned the car off then restarted.

Any ideas or experiences with the such? Any help would be appreciated.

Regards,

**cyberdyne** · 03-20-2007, 11:39 PM

I had this happen just before I had my alternator tested. Turns out it was on it's way out.

If you have heated seats, do the switches for these blink as well? That is a pretty sure sign it's the alternator.

- Steve

500MPL · 03-21-2007, 12:59 AM

No, the seat heaters don't blink. It is just the recirculator switch that does.

I had the brushes changed not that long ago, approx. 9 months ago. Haven't had any other troubles.

Did you have any other symptoms on your car?

Regards,

500MPL · 03-21-2007, 01:01 AM

I needed to make another post since the last was #666.

Regards,

axeman59 · 03-21-2007, 08:11 AM

ive got a euro 500sel and had the same problem as u i changed the fuse and@the same time i cleaned the connections in the box its worth a try and its cheap by the way the merc that igot is the same colour as yours

alexnatt · 03-21-2007, 08:23 AM

I had the same problem last summer when I had the a/c on. It has been too cold to see if it continues, but I'm curious if you find a solution. I did change all the fuses so maybe that will cure it.

benzwag · 03-21-2007, 10:50 AM

It is possible that the ACC is sensing an overload and is turning off and resetting. If the ACC pushbutton unit senses an overload through any of its circuits, it goes off for 30 seconds and resets. This means it goes into heating mode, and turns off current to the circuits it controls, including the monovalve, the water recircualting pump and the vacuum changeover valve. You could test the various circuits by checking the resistances in the various inputs and outputs (take out the pushbutton unit, disconnect the 2 14-pin plugs, and using the ACC electrical schematic, test the various circuits. The monovalve should be about 15 ohms. Each vacuum switchover valve port should be about 55 ohms. The resistances of the temp senders are in the manual. The recirculating water pump should be 5 ohms.) If I had to bet what is wrong (other than a bad fuse number 5), it would be that the recirculating water pump is going bad and is drawing too much current, putting the system into overload and making it shut off and reset. I would just unplug the recirculating pump (a little cylindrical pump which lives under the monovalve) and see if that doesnt fix it. You dont really need the aux pump anyway unless it is really cold out and you idle a lot. Or you could test the current going through the pump and see if it is a lot more than the spec amount, which is in the ACC manual, but about 1 amp IIRC. Have fun, Charlie