Heat/AC panel and fuse 48

[powers1]

Originally Posted by c4racer

ya - I forgot the numbers, I swapped in a 10A instead. the 7.5A would not blow immediately, but at least during summer months when using the AC it would occasionally go out.

Glad you confirmed that
We should tell "smoothhd" to try the 10A,as its only 2,5A more and will not cause any circuit overheating.
He probablly just something in the a/c-heater circuit consuming slightly more than the 7.5 A.
If its something more serious,the 10 A fuse will also blow and he will have to look into the problem further.

[Helmuth]

Maybe you connect an Ampere meter instead of the fuse (switch to 10 Amps before). Then you might see if that current flows always or only if you press buttons ..........

Just my 2 Cents

[c4racer]

Originally Posted by Helmuth

Maybe you connect an Ampere meter instead of the fuse (switch to 10 Amps before). Then you might see if that current flows always or only if you press buttons ..........

Just my 2 Cents

not a bad idea - in my case it never blew while hitting buttons and seemed quite random, so probably would be tough to diagnose that way. My guess is that something jumps up to 8 or 9A once in awhile and blows the 7.5A fuse. But knowing German design practices I bet the circuit has plenty of margin to supply 10A if needed. If my 10A fuse ever blows I am going to need to fix whatever is happening on mine!

[smoothhd]

there is a service bulletin addressing this exact problem. It suggests checking wiring around aux water pump and behind glove compartment. Think I will hold off on replacing the recommended 7.5 amp fuse with a 10 and do more investigating.

[c4racer]

Originally Posted by smoothhd

there is a service bulletin addressing this exact problem. It suggests checking wiring around aux water pump and behind glove compartment. Think I will hold off on replacing the recommended 7.5 amp fuse with a 10 and do more investigating.

do you have a link to the TSB?

[mp4.6]

I went to turn on my fan the other day and it didn't work (all the A/C buttons worked), I thought maybe I'd shorted something out replacing my interior lights with LEDs, but that didn't make sense (not that car problems ever make sense). I was going to look at the fuses, but I wasn't sure where they are, I would guess where the battery is? The parts guy at the dealership said it might be the final stage resistor that is behind the glovebox. I am not sure where to start.

[smoothhd]

here is a link to alldata where I found the TSB:
http://library.alldatapro.com/alldat...3452/122641646

[powers1]

Cant access it

[smoothhd]

i'll have to cut and paste it then when i get back to work. guess u need a subscription to use alldata no matter what. it basically says to check wiring in several locations. i checked some of the places that easily accessible and relocated some places that looked questionable. the fuse hasn't blown for 7 days with me constantly messin around with controls. guess i'll tear the wire harness apart in those locations and see if there is anything bare that can be shorted out.

[c4racer]

Originally Posted by smoothhd

i'll have to cut and paste it then when i get back to work. guess u need a subscription to use alldata no matter what. it basically says to check wiring in several locations. i checked some of the places that easily accessible and relocated some places that looked questionable. the fuse hasn't blown for 7 days with me constantly messin around with controls. guess i'll tear the wire harness apart in those locations and see if there is anything bare that can be shorted out.

seems to me if there is a short it would blow a 10A just as easily as a 7.5A. In my case I blew a couple 7.5's, but since switching to a 10 it hasn't blown in 6+ months.