Last night found I had no blower and CCU did not seem to do anything (no clicks, that I could hear)

Checked all fuses, esp 14 & 8. All good.
Checked blower resistor connector. Good

About to go dig further:
- See if there is 12V from pin 2 of resistor plug to ground with defrost on.
- Check at blower itself if there is power to motor? Try 12v to motor.

Some questions:

- Ground G102 - anyone know just where that is?
- For blower to run, does engine have to be running. That is, which position should key be in?
- On **************, Kent says a vacuum problem could prevent blower from running? Anyone know more?

I need to locate the blower wiring diagram. I had it, but can't now find it on the on-line Startek manual or on my old CD That's the one that shows the resistor and it's pin numbers) OK, found it again. Page 303 has resistor plug. Thinking 12v pin 2 & ground and blower should run?

https://www.dropbox.com/s/mbe6wvc73n1c26b/Blower%20wiring%20and%20other%20diagrams%2083_acc.pdf?dl=1

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Good luck Graham. I;m chasing same issue down with our 95. Blower motor good, strap fusse good, CCU operated compressor and flaps, resistor replaced, still no function.

the blower is probably bad - thats a likely culprit.

i have to do the same dive on my new to me wagon.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

The key has to be in "run" for the blower to operate. The engine doesn't have to be running.

Don't discount the possibility of broken solder joints on the pushbuttons in the CCU. I had the fan keep cutting out in my SDL and that's exactly what it was. Compressor would run and all the functions seemed fine, but fan would randomly just drop out as you drove down the road, sometimes staying off for periods of time before coming back on.

If everything seems to be dead, try replacing the fuses (even if they test good). Moving from there, make sure you have power at them with the key turned to "run". If no power, the issue is probably in the key switch.

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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!)

Spent good part of the day on this and still not corrected

- Fuses replaced and checked
- Resistor has continuity and connector is sound
- ~12V to ground from resistor pins.

On to next steps:

- Unplugged blower and checked voltage at plug. Good at ~12v.
- Removed blower and set it up on bench with lawn tractor battery/charger. Works at high and low voltages. Never misses a beat when continually connecting and disconnecting
- Before re-installing connected blower to plug. At first nothing (remember, I have 12V on plug and I know blower runs). Wiggled plug and blower ran! Noticed plug was loose fit, so repaired plug so it fits tight. Celebrated (prematurely )
- Reinstalled blower, plugged in and tested again - Nothing - zilch.
- Took blower out again, tested on bench, checked connections, everything good. Hooked up again and it worked. However, noticed it sometimes only worked on other settings if I ran defrost first??
- Anyway re-installed and it was still working. So replaced dash panels.
- Tested again - Nothing!!!
- Took out pushbutton unit. Connections good. Still no go. Buttons do activate servos (can hear clicking)
Called it a day.

So either bad CCU or blower needs brushes or ????

Next step, probably is to open up CCU and look for bad connections.
Probably replace brushes too once I figure out how to get motor apart.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Unplug the aux water pump and see if it comes back. A shorted aux pump will shut down the system.

OK - Worth a try. I see Programma says to check the pump and says to check amperage draw:

http://www.programainc.com/docs/31285.pdf

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

The w123 blower has a ground switch on the thermostat housing. This will prevent a blower to go on right away on a cold engine and blow cold air to the passengers. The switch will activate when the engine is warmed up a bit. Can't remember the temperature. This will turn on the blower.

You might have a faulty switch. Unplug the wire and test it by jumping the wire and grounding it.



.

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1983 123.133 California
- GreaseCar Veg System

Again, worthwhile checking!

By the way, found this good write-up on how to open up the push button unit to check for bad joints:

Mercedes w123 Maintenance: Automatic Climate Control Unit Repair

Adding here for future reference.

Taking a break - have a couple of jobs to do on E320.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I played a bit with the blower controls in my 1985 300D. I used a climate wiring schematic that has been posted here many times (for a 1984 I recall). In my case, the issue was high resistance at the #8 fuse-holder (which likes to melt). In both my cars, I ran a feed wire straight from BATT+ (pushed thru feedthru under battery) and added a 40 A relay so the factory 12 V supply wire just turns on the relay (see post w/ photos). But you may not need that.

You might first focus on the blower relay box, which is the black plastic one above the glove-box. It is just a bunch of relays which get inputs from the TemperatureRegular box next to it to set 1 of 6 (?) blower speeds, by switching in different resistors (engine bay, front passenger side). You can actuate those yourself by applying 12 V to each pin. Monitor that your 12 V supply pin holds. The relay box also gets inputs from the push-button switch. In auto-speed, the temp box has control. In H, one speed is fixed (highest, i.e. no resistor?) and L sets another speed. Perhaps those inputs flow as requests to the temp box (schematic will tell).

I recall the ground for the blower is above the passenger's right foot. If you remove the under-dash panel and glove-box liner, you should see a stud on the right with many brown wires attached.

I might have bypassed the "coolant temp switch lock-out" in the T-stat housing (connect 2 wires together). That avoids blowing cold air on the passengers by disabling the blower until the coolant warms up (German mothers fear drafts cause illness).

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I found this one in one of the threads. Not sure it tells me much!

This one is a bit easier to read and confirms it applies to 123.133.
https://1drv.ms/b/s!AoH5ntx7CT_FlQQNVqbhIMqe3Ft1 (If you get message asking you to join, just click on No Thanks at bottom)

There was no sign of overheating on Fuse 8 or it's holder. I changed it out anyway.

Car is being used most of this week, so won't do much until weekend. Meanwhile Coolant & PS flush on W210 in 6C weather

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

My son used the 300D today. Said the fan & heater worked fine????? Maybe what I did fixed it??? By the way, he said the fan came on right away when he started car (1deg C this morning) He turned it off then turned it back on later. Engine would not have been anywhere close to 35C, so don't know how that temperature switch works.

Will see how this goes. Could be an intermittent problem still.

Worked again today Thursday.

Worked again Friday, but son said it at first did not come on

Today, -8C I heard scraping noise from blower and then nothing. Drove car about 20 km and no blower.

To be continued.....

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

As noted above, after working mostly this week, back to square one. Nothing working.

- checked fuses again - all good
- disconnected aux pump. No change.

- Checked resistance of temperature switch on side of tstat housing - no resistance (car warm)

- Tried grounding line to temperature switch. This results in clicking in KLIMA unit (just in front of fuse panel (on 85's only?)


The diagrams don't show the KLIMA unit, but presumably it must also have a relay that uses that temperature switch?

Anyway, moving on again to blower and maybe CCU and other stuff mentioned behind dash.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Took panels off, gave blower a thump and it ran!

Pulled Blower and dismantled it. Brushes worn, commutator dirty. Bearings seem OK. No need to remove impeller cage on blowers with this Bosch motor

Will look at posts on replacing brushes & cleaning commutator. Alternatively see if surplus motor I posted about might fit. Or get a Volvo motor. Or buy a Uro blower. Decisions, decisions

Attached Thumbnails

   

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

You get First Prize

Have another thread more focussed on the blower motor repair/replacement

W123 blower dimensions

ADDED Installed new motor and everything works great!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5