I have a 1997 S-500 with 44,000 miles on it.
AC works great (cold air, etc) but the blower seems to have a gremlin. One second it will blow full blast and then it turns off (control panel shows the AC on high and then changes to off) - I saw it this morning in the span of 1 minute go from high to low 6 times.
Maybe the cabin thermostat is bad? Loose connection? Any ideas or troubleshooting would be appreciated!

Thanks

Is that a W140? I think you have the same regulator as is used in my W210, but with a different wiring harness. On the W210, this is a fairly high-frequency failure part, but usually presents as the fan not going higher than half speed.

do you have control of the blower speed? Can you adjust it to various speeds and have it hold. If so, that woud seem to say regulator is okay and point to control unit as the problem.

It's the blower regulator.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

the blower regulator? THANK YOU! BUT can you tell me where that part is? Is this an easy fix or do you have to take out dash???

Thanks!

I'm hoping that someone else can help you, as I have no idea where the blower is on your car. I would bet that it's pretty easy though.

With the new part in hand, it's a good fifteen-minute job on the W210. Sixteen minutes if you also replace the charcoal filters.

The 140 car is equally easy. The regulator is part of the blower, but can be re[placed separately. The blower is in the engine compartment in front of the passenger. There is a large black cover that covers it and most of the rear of the compartment. It is held down with a number of large phillips screws. (real large). With the screws and some trim removed the cover can be folded over and back to avoid disconnecting a number of vacuum lines. The blower is under the dust filter and the regualtor is on top. The blower does not have to be removed to change the regulator.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

please report back with solution to problem.

Pulled the cover to access the blower and regulator.......DISGUSTING filter! Tons of leaves and stuff....so vacummed out leaves and debris under the windshield wipers and cleaned up filter as best I could......ordered new ones - so will have to disassemble again to replace filters. As of right now, gremlin is gone. Blower seems to be working correctly. I did unplug and reconnect all wiring ontop of blower to make sure not loose.....nothing appeared to be, but you really never know!

Very simple to access and right now seems to be OK....will report back with any changes....thinking the regulator is on way out.

started tinkering around with potential suspects in the AC Gremlin...appears the culprit was the Interior Temperature Sensor (the one mounted in the dome light/moon roof switch/etc.) The little fan was plugged and not pulling any air. The diagnostic (press Rest button for 6-8 seconds) shows the right interior temperature and is now changing.
All appears to be working correctly.
Thanks for all help!

Did you replace it or remove the dust?

just cleaned it up.....sprayed some computer keyboard cleaner (you know that compressed air stuff) on it - blew lots of dust out. Got the fan spinning again....honestly, didn't expect it to work......

Well, thought the system was all fixed. Alas, no.

The AC is cooling wonderfully - but it seems to have a blower problem. First problem was that it wouldn't stay at one level - cleaned out the cabin temp sensor and that seemed to rectify the situation....now when I turn (relatively sharp) or hit a bump, the blower goes off. Stays off for about 30-45 seconds and then starts again. Other than that, the air is cold and the blower does work. Does not do anything if on freeway or no turns. Is there a loose connection that could do this? Perhaps blower regulator???

Thanks

Any thoughts or ideas on what would cause the blower to kick off and then come back?