Climate Control Fuse 48 Blows

[shark88]

My first post to this forum and my problem is the #48 fuse is intermittently blowing. No real pattern that I can find. I bought this 2002 X5 3.0 w/92,000 miles in March this year. It just started doing this about a month ago. I've cleaned the dust out of the controls, the compressor draws about 3.5 amps and drops as the system runs. I have a set of 134a gages and I'm seeing 40-45 psi on the low side at 80F - 85F, about 200 - 300 on the high side. The aux fan seems to "bump" once or twice before spinning up to speed when the snowflake button is pressed. I have a cup holder full of blown 7.5 amp fuses and really am at a loss on this one! Any ideas?

Current Rides:
'88 635 CSI (mine)
'02 X5 3.0 ("tank thing")
'01 325CI Convertible (wife's)
'06 325i Sedan (daughter's)

[williamx5]

Good day!!

I looked up the pin for Fuse 48 and it goes to Module A11 (IHKR-Automatic Heating/Air Conditioning Control)... BMW did a redesign in 09-2000... Which, didn't matter in your case as they are all the same concerning this fuse...

The Fuse connection goes to A11 Conn 0 (zero) Pin 1 and is described as "Throttle Actuator Terminal 30 Voltage Supply"...

Maybe it controls the "Full Throttle Cut-out" for the A/C... I'd have to dig deeper to give a better answer on the description meaning... Do you use the passing gear a lot or have a lead foot and like to get the X moving quickly?

Maybe someone else could chime in with their experience...

Good luck!!!

Cheers!!

[shark88]

It has blown the fuse 3 or 4 times on me just pulling out of the neighborhood so I can probably rule out the full throttle cut out. It can go 3 - 5 days and work fine. I drove it to work all last week, 140 miles ea day and it blew Wednesday morning a few miles from home. I keep coming back to the aux fan and it's erratic 2 or 3 bumps before it spools up to a constant speed, Does anyone else's 3.0 fan operate like that?

To expand more (and add to the mystery), the first time it did this the wife was driving on the local perimeter hwy doing 65+ when she had to slam on brakes for someone who had come to a complete stop! I've had it blow 3 times just easing out of the neighborhood in the morning and last Wednesday's event on a 55mph hwy close to home. I have gotten in the habit of turning the snowflake button off before shutting the ignition off and waiting a minute when I start the engine before turning the snowflake button on. This has not resulted in any blown fuses.

Thanks

[shark88]

It has blown the fuse 3 or 4 times on me just pulling out of the neighborhood so I can probably rule out the full throttle cut out. It can go 3 - 5 days and work fine. I drove it to work all last week, 140 miles ea day and it blew Wednesday morning a few miles from home. I keep coming back to the aux fan and it's erratic 2 or 3 bumps before it spools up to a constant speed, Does anyone else's 3.0 fan operate like that?

To expand more (and add to the mystery), the first time it did this the wife was driving on the local perimeter hwy doing 65+ when she had to slam on brakes for someone who had come to a complete stop! I've had it blow 3 times just easing out of the neighborhood in the morning and last Wednesday's event on a 55mph hwy close to home. I have gotten in the habit of turning the snowflake button off before shutting the ignition off and waiting a minute when I start the engine before turning the snowflake button on. This has not resulted in any blown fuses.

Thanks

[williamx5]

Ummmm... Okay, so I guess the fuse kills the controls to the climate control?? Or does it just disable the interior fan?

Are you referring to the aux fan in front of the radiator? I don't think it's operation would have anything to do with the fuse that is blowing...

I wonder if there is something that moved about in the cab, when the wife slammed on the brakes, that caused the wires to chafe thru...

I'm gonna go take a look at the connector... I guess it is possible that there is a short in the controller somewhere... You have access to a spare or known good working controller you can swap in and test?

Cheers!!

[williamx5]

From what I have read, the module (IHKR) controls the A/C clutch directly... Since that three wire connector going to the back of the IHKR is the only one that looks as if it could handle the current needed to power up the magnetic coil on the compressor, I would imagine that is the issue. The aux fan is controlled by the DME, but sends signals to the IHKR to turn the compressor on or off via the CAN/K-Bus...

So, my interpretation of this is the on/off of the magnetic clutch is causing an overload on the IHKR, that is popping the fuse... The test to this would be to NOT run the A/C... Not the best idea, so we'll have to figure out a way to isolate the issue... You in Georgia? I think I have a spare compressor for a 540i... The magnetic clutch might be the same as what you have... I'll do some research... EDIT:: The compressors are not the same... The magnetic clutch might be the same though...

Ideas?

Cheers!!

[wpoll]

It's normal for the aux. fan to twitch a few times before it starts running - it also does this when you turn the car on.

[shark88]

Originally Posted by wpoll

It's normal for the aux. fan to twitch a few times before it starts running - it also does this when you turn the car on.

wpoll, thanks for that info! I wonder if my E46 does it too.....

[shark88]

So this morning it blew #48 after I had driven at least 3 miles w/the A/C off. It still went about 2 more miles with the A/C on before it blew. This afternoon, I thought about what I work I have done since I purchased it in March and if I could have done something to cause this issue. In early April, I replaced all the pulleys, tensioners and belts. In May, the week before it first blew (when the wife slammed on brakes) I put a new fan clutch on it. One thing I had noticed was the PO or PO's mechanic had broken the slotted tab on the fan shroud that the aux fan connector clips into. It was tie-wrapped to the compressor discharge hose which gets pretty hot. The connector also had a tie-wrap around the connector halve holding it together. This afternoon, I cut all the tie-wraps, inspected the connector and wires for any issues, started the engines and wiggled the wires and connector hoping something would ground or short out and blow #48. Nothing happened so I tie-wrapped the connector back to the broken fan shroud tab which has two openings to facilitate this. I have to go run a few errands this evening so I'll start out with no A/C and see what happens down the road. Thanks for all the input n this!

[shark88]

Originally Posted by williamx5

From what I have read, the module (IHKR) controls the A/C clutch directly... Since that three wire connector going to the back of the IHKR is the only one that looks as if it could handle the current needed to power up the magnetic coil on the compressor, I would imagine that is the issue. The aux fan is controlled by the DME, but sends signals to the IHKR to turn the compressor on or off via the CAN/K-Bus...

So, my interpretation of this is the on/off of the magnetic clutch is causing an overload on the IHKR, that is popping the fuse... The test to this would be to NOT run the A/C... Not the best idea, so we'll have to figure out a way to isolate the issue... You in Georgia? I think I have a spare compressor for a 540i... The magnetic clutch might be the same as what you have... I'll do some research... EDIT:: The compressors are not the same... The magnetic clutch might be the same though...

Ideas?

Cheers!!

I believe you are correct with the operation of the IHKR, aux fan and the AC compressor. From what I have read, no relay is involved for the compressor. I am near Athens GA and I may be able to borrow or purchase a clutch from a local source but thanks for you diligence with this!