I have and 82 300SD. I have no blower motor. I get heat, but the blower never comes on. I replaced the control unit twice...each time it works for about 10 minutes then nothing. As soon as I switch it off or change to another button (from defrost) nothing works. I have also replaced the blower motor relay. I'm wondering if the motor is going bad (i.e. bad bushings) and is drawing too much power and somehow frying the control unit?

What else is possible? Is there another relay I don't know about? Regardless of the temp, the defrost should work right? Is there any way to test the relays?

No having a blower is getting real old.

anyone?

Are you saying it works on defrost but nothing else? Or that it only initially works on defrost and afterwards will not work at all, including defrost?

I believe I have read on this board that a failure in the auxilliary pump of some kind will cause the pump to draw too much current and burn out the board in the control unit. Some people put a fuse in the auxilliary pump circuit to stop this problem I believe. Perhaps this is your issue.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

This problem appears to be pretty common on high mileage D's. And it may very well be the CCU board. I received a CCU from an 83 300D the other day that I got from a salvage yard. The board is enclosed in a plastic box that looks like it can be opened up but am still trying to figure out how.

The box has slits that is probably for venting. I sprayed contact cleaner thru the slits and the cleaner residue that came out looked blackish. This tells me it gets dirty in there (after 20+ years).

I'm still trying to figure out how to open the box to get to the board. Someone said that the circuit board may develop cracks and open some circuits which then requires some soldering. Spraying contact clleaner maybe all it needs.

The other thing I am trying to figure out is how to remove the CCU from the car. I'd like to swap the units when I figure out how to remove it.

Any info would be apreciated.

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the sooner you start... the sooner you'll get done If it ain't broke, don't fix it.. Its always simpler to tell the truth...
2007 Honda Accord EX
2007 Honda Accord SE V6
96 C220
97 Explorer - Found Another Home
2000 Honda Accord V6 - Found Another Home
85 300D - Found Another Home
84 300D - Found Another Home
80 300TD - Found Another Home
Previous cars:
96 Caravan
87 Camry
84 Cressida
82 Vanagon
80 Fiesta
78 Nova
Ford Cortina
Opel Kadet
68 Kombi
Contessa

I've replace the control unit twice, is that the ccu you are talking about? I'm very leery of replacing it again, especially with a new one. I may just take it into the shop. I'll explain everything so that way if it goes up again, its on them and I won't have to spend more cash on it.

As for removing the ccu, if its the one that sits behind the bottons on the center console, then its easy to remove.

Have you checked the resistance level of the wiring? Yes, the Aux water pump does draw power from the CCU, that is why many people, myself included, installed a 1 amp fuse in the power circuit of the aux wp.

That chirp sounds like a capacitor when it blows.

Have you tested the blower motor off of the battery? Have you also tested or unplugged the auw wp? Stiff motor bearings or soemthing preventing the motor from spinning will result in higher amp draw, which in turn will cause blown fuses or components.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

All the settings work initially for about 10 minutes. Which pump are you talking about? I was suspecting the motor was drawing too much and was wondering if it drew power through the control unit. Each time the board goes up I hear a chirping very briefly. It sounds similar to a hooter valve on a turbo (if anyone owns a Saab, you know what I'm talking about). That is why I thought it was a vacuum noise but I suppose it could have been a bushing dragging.

It's the auxilliary water pump, plumbed in line with the heater hoses to push coolant thru the lines at low rpm's. I'm not sure of it's location on the SD. if you follow the heater lines under the hood, it should be visible.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

It sounds as if you've deduced your own problem. Sometimes you can get more life out of the motor by changing just the brushes. When you pull the blower, check the armature for scoring or excessive wear. If not too bad, give the brush replacement a try. Replacements are available, along with instructions, at www.**************.com

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Sam

84 300SD 350K+ miles ( Blue Belle )

tobybul, I have watched a CD-ROM on removing it, { available from Repairflix.com } pull ashtray, there are 2 screws, remove, pull whole unit out, might have to unplug an item or two. On the radio bottom there are two "tangs" two little things, pull down and slide toward rear of car, unplugging what you need to. Using a stubby phillips screw driver, remove two screws, the wood laminate will drop down slightly and lift out of the way. The switches push out from the back, if you need to deal with them. Then you will be able to see two bolts, on the upper sides of the CCU, they screw into plastic I think. Remove, and you should be able to pull out the assembly. I went to the local pick'n'pull today and saw three CCU boards that were seriously fried, albeit not on a 126, or 123. Other posts seem to cover these problems. Hope this helps.

All folks should become familiar with this little 4 step process:

Click on "Search"
Select "Advanced Search"
Type in Subject..........
Select "DIY Links by Parts Category"

WHunter has done a lot of work putting this together. Usually there are photos and several posts that cover the different models.

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Sam

84 300SD 350K+ miles ( Blue Belle )

All folks should also become familiar with reading the original post. I said I already had that article and it was a bit vague. I was looking for extra info, extra pictures or tips not listed.

Sorry, I'm not familiar with what "that" article is, as there are at least three of them. In your defense, the third one (mywebpages) that has the most detail is not currently a working link.

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Sam

84 300SD 350K+ miles ( Blue Belle )

On the DIY Articles page, there is only one auxiliary water pump replacement article that I know about.

Replacing the pump looks daunting because you can't see it. But, if you remove the section of the forward firewall, the job becomes effortless. The pump becomes visible immediately and you simply disconnect the hoses and replace the pump.

Removing the battery is preferable to give you some additional working room and to easily access the connection plug.

Get the shopvac out and clean the area below the pump before installing the new one.