I agree, I bet with some patience and labor one could replace the items on the CCU that get fried if the pump goes out. Just gotta be very steady with that soldering iron!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Oh yeah.......you definitely know your way around the area between the firewalls........looks like surgery in there.

I forgot about that "little" project.

Well, Brandon, if you're up for it, I'll be happy to send you one for experimentation.

Brian,
Check out this post to see what I did to remedy the problem. My ACC is flakey as of late but there is no way it is the aux pump any more as it is isolated completely and continues to work. RT

Arrrgh! Auxilliary coolant pump leaking.....

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

Thanks Rob.

I just replaced the pump with a new one. They are on e-bay for about $50.00 or so. I had already bought it as a spare...........smart thinking, heh?

I'm going to get a fuse put inline with the 12V supply for the new one. I don't see the need to bother with a relay for it. Just one more thing to fail down the road.

Have any way to email me a picture of the circuit board front and back and perhaps show which trace on there goes to the waterpump?

I'd be all for fixing one up. I have a little pile of cruise control amps to fix too

Odd though...all my stuff works in my car

In taking the back cover off, I saw traces of burning. You'd need to dismantle the whole unit to get at the front side of the board.

Like I said.........it's yours if you want to get into it.

I found a nice ATO fuse holder at Autozone, but anyone have any idea where I can get a 1amp ATO fuse? I tryed the local Radio Shack but, well you know

Oh PS My ACC really freaks when I put my hot coffee mug over the sensor on the dash I used to put that there with the 240 on a regular basis.

__________________
1984 280SEL, 62,000 miles
Euro model in the USA
1983 300D (Totaled out 10/2004)
New Factory Mint Green paint
Palomino int
1982 240D (Steak dinner for two)

What a timely bump. Would a bad aux pump be the main reason to blowing the fuse? The #5 fuse on my new 86SDL keeps blowing, sometimes lasts 3 hours when driving, sometimes 15 minutes.

According to the Fuse Designation label, The #5 fuse controls:

• Back up Lamp
• Heating Water Valves
• Water Pump
• Climate Control System
• Relay Aux Fan Terminal 86
• Aut Transmission Electronics
• Blower Motor inside temperature sensor
• air conditioning compressor
• electromagn. clutch/valve air injection

__________________
91 350SD
14 F150 Eco
19 Fusion Hybrid
11 GT500

It could be the aux. pump, but, even when fully stalled, it shouldn't draw anywhere near enough to blow the fues.

The only other item on the list is the aspirator motor. This item is noted to seize after 20 years due to lack of lubrication. It's sitting above the passenger kick panel behind the dash. I wouldn't think it could draw more than the 8 amp fuse can handle, but, you never know.

Aspirator Motor? Is that the blower motor? Actually there was a 15A fuse in the spot and it was blowing that!

__________________
91 350SD
14 F150 Eco
19 Fusion Hybrid
11 GT500

When I bought my 84 300 SD the fan had a larger fuse installed. Shortly thereafter the climate control unit stopped working (along with the fan). I was able to disassemble the CCU and found a circuit burned. I took solder and bridged the gap in the circuit and the CCU is functional. The circuit probably would not have burned if the correct size fuse was installed.
The problem was the water pump had siezed. I removed it and connected the hoses together. I've been running like this for a few years. The heat works OK but my wife's 83 SD heater works much better.

It's a small motor and fan that draws air down from the tiny grille in the overhead console. The motor keeps airflow across the thermistor so that climate control can reliably know the cabin temperature at all times.

A separate unit from the blower motor.

Thanks for the "bump"
I have done all the mechanical stuff to my SD, but haven't driven it enough to know what other problems I might have.
I did change the anti freeze the other day, and had no heat at idle, but on a short trip around the block, I had copious heat--but only thru the defroster vents. I could not get air flow from any other place.

I assume I need to replace, or by-pass the electric water pump. I am guessing that I need to remove the Climate Control Computer and see if it is fried.

One more sympton, the aux electric fan runs continously. Could all this be tied to the CCC? What are the odds that a simple resolder of the CCC will fix these issues?

After working correctly in the garage for the last year, the OEM Becker radio now refuses to work. I get some noise and a portion of the display. Could this, too, be related to the CCC?

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

Air through the defroster vents is a sign of vacuum problems in the pods, not a bad CCU. You'll need to open up the switchover valves (passenger side of the transmission tunnel) and use a Mityvac on each circuit to find the pods that won't hold vacuum. It's a bit of a job, but to get the remaining doors to work, and the defrost to close, you'll have to tackle it.

The electric fan has two sources to start. The most likely source is the switch on the dryer. Disconnect the leads to the switch and see if the fan shuts down.

Although you seriously wish the CCU to be the culprit for all the issues, I don't see the CCU as the problem for any of them at the present time.