83 300d acc unit

[Serge A. Storms]

I own an 83 300d.
I have replaced the blower motor and the acc unit after having the #8 blown fuse problem. Now instead of blowing the fuse it gets blistering hot, after pulling the fuse the #8 slot has melted. Any advice or fixes would be greatly appreciated as I am roasting alive every day.

[CoffeeGuy]

It is getting hot because of resistance, check your grounds, clean the negative batter terminal, and the ground wire from the battery to the chassis. Also check any other ground wires for fuse box and blower motor.

[Brian Carlton]

There is a 30A shunt that is designed to fix this issue.

I'll see if I can find a p/n for it.

Also, try unplugging the auxiliary water pump and see if that helps. If that pump is drawing high current it can smoke your ACC unit.

[AMH]

Originally Posted by Craig

Also, try unplugging the auxiliary water pump and see if that helps. If that pump is drawing high current it can smoke your ACC unit.

Fix for aux water pump.
Two wires coming out of pump, black is hot and brown is ground.
You will need NAPA # 7823101 (Marine grade fuse holder) and a 7821042 one amp fuse. Splice the fuse holder into the black wire, if the pump does seize it will blow the fuse and not toast the CCU.

Alan

Originally Posted by AMH

Fix for aux water pump.
Two wires coming out of pump, black is hot and brown is ground.
You will need NAPA # 7823101 (Marine grade fuse holder) and a 7821042 one amp fuse. Splice the fuse holder into the black wire, if the pump does seize it will blow the fuse and not toast the CCU.

Alan

That is a good idea, I've replaced my pump but I've never bothered to put a fuse in the line.

[Brian Carlton]

Originally Posted by Brian Carlton

There is a 30A shunt that is designed to fix this issue.

I'll see if I can find a p/n for it.

This is the component that you need to fix that issue:

http://www.performanceproducts4benz.com/productpage.aspx?cid=10&sid=75&pid=102731

[Serge A. Storms]

Originally Posted by Brian Carlton

This is the component that you need to fix that issue:

http://www.performanceproducts4benz.com/productpage.aspx?cid=10&sid=75&pid=102731

Thanks Brian,
In the mean time I unhooked the aux pump and # 8 is still heating up, a friend has my volt meter so i haven't had a chance to see if it's drawing more than it should. Am I right in assuming that the 30A shunt will take the place of #8 on my fuse panel?

[fdanielson]

The fuse is getting hot from the current that the fan draws. Try removing the fan and cleaning the armature and oiling the bearings and bushing. There's been a number of threads on this. Try searching for blower brushes or fan brushes.

The retrofit kit to use an external higher amp fuse will also help.

[Serge A. Storms]

Originally Posted by fdanielson

The fuse is getting hot from the current that the fan draws. Try removing the fan and cleaning the armature and oiling the bearings and bushing. There's been a number of threads on this. Try searching for blower brushes or fan brushes.

The retrofit kit to use an external higher amp fuse will also help.

I have already replaced the blower motor and the acc unit.

[Cr from Texas]

With new or used parts?

[Brian Carlton]

Originally Posted by Serge A. Storms

Thanks Brian,
In the mean time I unhooked the aux pump and # 8 is still heating up, a friend has my volt meter so i haven't had a chance to see if it's drawing more than it should. Am I right in assuming that the 30A shunt will take the place of #8 on my fuse panel?

Yes, the 30A shunt screws into the bottom of the fuse box and takes the place of #8. Get the procedure to pull the box from the top.........crawling beneath the dash to attach the shunt is a nightmare.

[Serge A. Storms]

Originally Posted by Brian Carlton

Yes, the 30A shunt screws into the bottom of the fuse box and takes the place of #8. Get the procedure to pull the box from the top.........crawling beneath the dash to attach the shunt is a nightmare.

I have the shunt and I have searched the diy section but I haven't been able to find this procedure, should the shunt be wired directly on # 8?

[Brian Carlton]

Originally Posted by Serge A. Storms

I have the shunt and I have searched the diy section but I haven't been able to find this procedure, should the shunt be wired directly on # 8?

On the bottom of the fuse box are screw terminals. The shunt attaches to the screw terminals and the fuse is removed.

However, there is a technique to lift the box from the cowl so you don't need to crawl under the dash with one arm and one eye............