My 1979 W116 and 1980 W123 diesels both have blower problem with blower not shutting off. I have heard that there is a regulator box somewhere. Blower motor is fine....tests good.

Anybody know where that regulator box is???

I only need 2 blower states......full on and off. Heat only. a/c is gone years ago.

Can I patch out the regulator box so only the defrost console button gives me full speed (as it now does) and the off button removes power???

__________________
Dionysius

Anybody have a schematic or pinout of regulator if there is one??

__________________
Dionysius

The evil servo is truly evil. It's hard to imagine that the engineers who designed a car as good as a W123 MB would stick that Rube Goldberg piece of crap under the hood to control the heat/ac.

I replaced mine twenty years ago. When it went bad again, I just disconnected it. I live in perpetual summertime so I don't use heat. I wired shut the hot water valve on the firewall and run the ac on Defrost. The Defrost by-passes all of the climate control nightmare. It is a direct electrical connection to the blower and the compressor.

Richard

I have the schematics. I will get them together and post them for you tomorrow.

Richard

The beast has the automatic "climate control" the bete noir of the German car. What a nightmare. I tore into the w116 1979 300SD and found squeaky blower. Wife had not mentioned squeak which just started. It was lucky that I chased that issue first as you will see. Removed glove box and passenger upper kick panels. After some time (1.5 hours) I had the blower removed having fought with a captive nut that had come loose. It was one of 3 holding motor/fan to heater box. There was NO bearing play. I started with shooting WD40 into the motor and let it drift to bearings on top and bottom. Tested. Less squeak. More WD and some 3 in 1 oil was generously applied. Squeak gone.....and voila......the blower now switches off which is what I was after in the first place. My theory is that the WD40 acted as a cleaner to clean out the commutator grooves that may have been shorting. That is what was keeping it running. Anyone disagree????? Since it was running fine I did not replace brushes. I do not know how much brush is in there. I do not know if squeak was from bearings or from brush-comm. I now have car back in service......as before only 2 states: Defrost using full speed blower for heat. I deep-sixed the Chrysler loser "servo" years ago so no a/c which is fine with me. I should have torn out a bunch of pneumatic, elect, boxes, etc. Maybe next time.

__________________
Dionysius

WD-40 is not a lubricant, hopefully the 3-in-1 you used was in the blue can for electric motors, the black can will form a varnish and ruin the bearings.

The fact the motor is working now is coincidental. Perhaps you pulled on a wire with a flaky connection somewhere. Shorting bars on a commutator will cause the fan to draw excessive amperage and run slow or blow fuses.

If you got WD-40 on the commutator, pull the motor back out and clean that crap off. You'll ruin the commutator AND the motor brushes by leaving it on there. Use Acetone and clean the commutator and brushes well to get the oil and residue off, it has no place being there.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Appreciate your input Diseasel. The W116 motor is different from the one on the W123. Why do I say that???? Here is why. There is a closed housing with only a single port of access into it. I was or am not disposed to tearing the motor apart and rebrush it until the time comes when I have to. I never did pull the motor apart. My mission is to get the drive non-critical part back in within a few hours and I figure that the WD40 was my cleaner. Then I shot a fair amount of 3 in 1 to do the lubing. Of course I would do as you suggest had I decided on a rebuild/rebrush.

This motor never failed to run. It failed to turn off. You mentioned " Perhaps you pulled on a wire with a flaky connection somewhere. Shorting bars on a commutator will cause the fan to draw excessive amperage and run slow or blow fuses.". I am unable to point to any connection that would result in this symptom. Perhaps you might be more specific. I vibrated and rattled the hell out of it in initial testing but ran to perfection except for the squeak. There was absolutely no play radially and a tiny amount <1/32 inch (my guess) axially.

Since the motor is moving full air with massive torque I do not believe WD40 will destroy the commutator. The brush(soft carbon) on the commutator which is Cu is a self cleaning interface IMHO. I am NOT an expert on this but I do respect that you may have years of experience. The motor runs and sounds like perfection. Lets see how long it will last. If it runs until rebrush time then I know I am into it and I hope it will be in hot weather. When that happens I will report for the anecdotal benefit of this case.

I do think this is a great website.

Thank you very much for your posting and solid advice.

__________________
Dionysius

I repair and service DC machines for a living, so I might know a thing or two about brush/commutator maintenance ;-)

The brushes and commutator are porous. The thin oil in the WD-40 will soak in and "sweat" back out when the motor runs and heats up. Over time, it attracts dirt, dust, carbon dust, and moisture and creates an abrasive/corrosive layer that literally eats the copper off the commutator. If you've ever seen a deeply grooved commutator with a thick black layer on it, someone oiled it. The brush/comm interface should be nothing but copper/carbon. If kept clean, it'll last a very long time. If not, it won't. I should mention that oil is also flammable...

The motor will be switched either on the positive or negative side through both a switch and the motor regulator assembly (resistors in older cars, transistors in newer ones). One side of the motor will always be controlled in some form or fashion. The ONLY way for the motor to run when it shouldn't be is for there to be a short to ground in a system that's got the switching on the negative side of the motor, or a failed/stuck contact on one that is switched on the positive side.

The health of the motor has literally nothing to do with it running when it should be switched off. By fiddling with the wiring under the dash to drop the motor out, you may have "cleared" the short, or pulled hard enough on some wire somewhere to free up a stuck contact.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I appreciate gaining this insight. I had guessed you were a pro in this.
For clarification, when you say the Cu and the Carbon are porous can you elaborate some. At the atomic levels everything could be described as porous but that porosity would never allow oil molecules to invade. Maybe we are talking impurities or alloys in the Cu??? What am I missing here?

__________________
Dionysius

The brushes are porous by nature, anything carbon-based is porous (heard of activated carbon? It's REALLY porous!) They are an alloy of carbon and graphite, sometimes with metal mixed in (copper or lead or both) depending on what the application is. The carbon provides the conduction, the graphite is the lubricant. Oil will weep up in the brush and sit in the "pores" of the brush, then sweat out every time it gets hot (which is when it runs).

The commutator is also not pure copper, it is a brass or bronze alloy with a very high copper content. Some are lower in copper and actually have a yellow color to them. The alloy has a much harder surface and better wear characteristics compared to pure copper. Pure copper on a commutator would wear down very quickly in a motor designed for constant use such as a fan. Unfortunately, the brass and bronze are also slightly porous and will soak up oil like a sponge. It doesn't take much to cause nightmarish problems later on.

If you have the ability, it would be a good idea to clean the comm and brushes to get the oil off. If you don't care, that's one thing, but time is a lot cheaper than a replacement motor. Just sayin'...

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Thank you so much for such a complete response.

Would you care to wager where the squeak was from: bearings or comm (not both I assume unless condition existed for a long time)??

Also the striations or grooves on the comm are caused by what mechanism? You did state above that particles of dirt are usually responsible?? Maybe between the bars globules of worn particles cut loose but most should not persist since the brush will sweep them away or am I wrong on this one also??

__________________
Dionysius

The squeak could have been either bearings or brushes. It isn't uncommon for hard brushes to squeak at times, especially if they're worn and the spring tension is lowered. The bearings in the fan motors also tend to be sintered bronze bushings that will squeak/squeal when they dry out. Adding oil to a squealing sintered bronze bushing is a band-aid, the squeak will be back or it'll seize since the burned residue that caused the squeak is still there.

The sintered bronze bushing is porous by design and holds a given quantity of oil that it "sweats" while the shaft rotates in it, creating a very thin oil layer (exactly the same mechanism that's undesirable on the brushes/comm, but very desirable for a bearing). Once the oil evaporates or polymerizes, the bearing stops working and the shaft rubs. You can often restore one of these bearings by cleaning the contact area with solvent to clean away the sludge and re-open the pores, then soaking it in thin oil. You can often get several years of good service that way.

The comm and brushes will wear just from friction over time, but the wear is very even and predictable. Most dust/dirt/debris is self-clearing since there is nothing to hold it there. The brush tends to simply sweep it away harmlessly. This is where the oil contamination comes in - As it gets hot it polymerizes and becomes sticky. In addition to creating a poor brush/commutator interface, it holds dust and dirt in place and turns the brush into a grinding stone. As the brush starts eating the commutator, the oil residue holds more and more debris and the cycle accelerates. Cleaning the comm/brushes with a clean-drying solvent like Acetone will generally do the job well. Acetone has the additional benefit that any oil residue that is leftover will turn to a powder and will disperse when the motor runs.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Many thanks for all of the valuable info you have so graciously shared.

__________________
Dionysius

Isn't that the purpose of a forum?

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)