Once again trying to diagnose no low fan voltage in Auto or Low in the 1984 300D.

Have 5 ACC units from 1982-1985 cars, four of which have been re-soldered, those four operate the fan on high, NONE of the units will turn the fan on in "Low" or "Auto".

The blower controller relays click (have four of these and three temp regulators, all have been switched and swapped with the same effect) and I've even opened up one to WATCH the relays open and close depending on ACC settings.

Changed out the temp sensor on the dash with THREE different ones, tube is fine, NOTHING seems to change the fact that the fan gets zero voltage at the Low or Auto settings (get's batt voltage on High fan setting.)

So..., it's NOT the fan (rebuit, D/C'd and voltage to the fan checked), probably not the ACC units as most were out of working cars and have been re-soldered, all work (or do not work?) the same way except one that hasn't been re-soldered, it doesn't do anything. Tried FOUR blower controller boxes, all do the same clicking and none acts differently from another. Three temp regulators, again, all work the same way (maybe all of those are bad?) And three different temp sensor units.

Engine is up to op temp, the engine temp sensors are fine (the one at the thermo is old, not sure about that one), re-built monovalve, operates properly, rebuilt aux coolant pump, operates flawlessly.

Anyone have more ideas than what I could find in the archives of ACC posts I've gone through?

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1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Test op:

Attached Thumbnails

 

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Never a dull moment at Berry Hill Farm.

Seriously, have you checked continuity of the load/speed resistors out on the fender?

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Never a dull moment at Berry Hill Farm.

Sounds like while the relays are being switched that current is not passing through the contacts, like the line from the fuse to the blower controller has an open in it - or a break in that fuse. Maybe?

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Send me your e-mail address via a private message and I'll e-mail you a tech bulletin which is an ACC diagnostics,,,, should be able to help you out.

JCD

You mean the "bread toaster"?

Thanks, hadn't even looked there, I just read your post and went out and removed the POS, took the cage off of it and this is what I found (see bottom pics)





Note the rather burnt and "unattached" resistor wire. I'll try to solder a jumper in, but since it's not the same resistance, no telling WTF will happen. I have a spare car at Grimgaunts place, but nothing close to pull one of these stupid things off of. If I knew what the res was supposed to be on that loop, I could just solder in a megawatt resistor in it's place, but.....

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1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Mark up another troubleshooting success for R Leo....

Soldering a wire in probably will get it going until the toaster is hotter than the melting point of the solder and any thing but a huge wire-wound resistor will last only an instant. Check for bad connections where the toaster connects to the chassis wiring too...these things don't seem to fail that often.

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Never a dull moment at Berry Hill Farm.

Well, I just bent down the remaining wire and silver soldered it to the tab. Sure enough, works great. So I just need to pull one from a parts car (probably about the time summer is here!) and replace this one.



The failure was because that particular wire end was not crimped tightly, the rest are crimped well, that one was just barely bent over the wire. Also, the crimped conns are steel and they're all rusted, so the rest would probably have issues at some point. I'm sure since it was rusted and not a firm crimp, resistance just went up so high it burned out at that point.

So after COUNTLESS hours of diagnosis of all the "typical" failure components, it ends up at this POS that I always assume is good because I've never seen a bad one either.

OK, so I owe you another one. Pretty soon, you'll have to take my first born child!

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1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Glad I could assist.

But, no kids, please; Thing Two turned 21 yesterday. However, I will take the 1st 5-speed you come across.

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Never a dull moment at Berry Hill Farm.

Great, I got an AX15 in a Jeep Chero here you're welcome to!!

Got you beat on the ankle biter, mine is 22 with two kids

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1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Mercedes 5 speed.

BTW, there's two 'things'....Thing Two (21) and Thing One (24)....no ankle-biters yet (thankGawd!!!).

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Never a dull moment at Berry Hill Farm.

Look at the bright side Tom, it's not the half-ass digital ACC GM used in the 80's..

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One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K