02 BMW X5 AC AUXILLARY FAN PROBLEMS
 

I AM PRETTY NEW TO WORKING ON BMW'S. RECENTLY I HAD A CUSTOMER COME INTO THE SHOP WITH WITH A/C ISSUES. FIRST AND FORMOST THE AUXILLARY FAN WASNT WORKING AND THE A/C COMPRESSOR HAD NO VOLTAGE GOING TO IT. wE ENDED UP REPLACING THE AUXILLARY FAN. tHE NEW FAN RUNS NOW BUT ONLY IN HIGH MODE AND IT RUNS CONSTANTLY, EVEN IF THE A/C IS OFF. tHE A/C COMPRESSOR STILL HAS NO VOLTAGE GOING TO IT AND FUSES 34 AND 48 ARE BOTH GOOD. WHAT COULD BE THE POSSIBLE CAUSE OF THE FAN RUNNING ON HIGH CONSTANTLY? ANY FEEDBACK WOULD BE MUCH APPRECIATED.

Both the compressor and the aux fan speed is controlled by the DME. The DME sends a signal to engage the clutch on the compressor and sends a pulse modulated negative signal to the fan to set the speed of the fan. I would get software that is able to read the faults in the DME.

DIS GT1/Inpa software will probably help in diag..

Also, if the system is low on refrigerant, the DME will not command the compressor to turn on. What is the system pressure without the compressor running?

Thanks for the feedback guys, I informed the customer that we needed the software to be able to find the faults and suggested that he had the vehicle scanned at a bmw dealership but he insisted on us working on his vehicle and did not want to take it to a dealership. I actually charged the A/C system to .98 LBS and still nothing.

Have you tried disconnecting the wire to the compressor and applying 12 volt directly to the ac compressor to see if the clutch engages? Could also be a bad compressor clutch.

Do not apply 12 volt to the wire if it is still connected to the wiring harness as the other end of the wire is connected to the DME.

YES I APPLIED 12V TO THE COMPRESSOR AND IT DOES ENGAGE WITH POWER SUPPLIED TO IT.

So it appears that you are not getting a signal from the DME to the compressor clutch. You can back probe the wire connected to the compressor to see if there's a break in the wire. If there are no breaks then the problem lies with the DME or the module that control the HVAC system for the car. Does the snowflake light for the AC switch lights up when the switch is engaged?

I'm having the same problem....did you find the problem? Pleas keep us updated.

My snow flake lights up on the climate control but nothing happens. There's no voltage going to the ac clutch or any change in the vehicles's idle. I'm thinking it might be the dme.

Did you connect gauges to the high and low side ports and determine what the system pressure is without the compressor engaged? If the system is low, the DME will not engage the compressor.

I actually replaced the pressure switch so I had the system recovered, vacuumed, and properly recharged. Still nothing...blows ice cold once I send 12v to activate the clutch. Also installed new electric fan, which had stopped working...no the fan run on high all the time. I also replaced the coolant temperature sensor. I'm definitely not overheating. Any ideas?

I used scanner1.4 and found a code/fault for high pressure. ( I believe it was code 15). That's*after I replaced the high pressure switch. Fan seems to be working correctly now.

If the DME and AC system is giving a High Pressure fault that could be the reason why the fan is running all the time and on high. Could also be the reason why the compressor is not engaging because of a high pressure condition.

Do you think it likely I got a defective pressure switch or that the dme is toast. When I bought the truck it had a 12v run to the compressor..and all the connectors were left plugged in. Maybe the dme shorted out??

Reason why someone ran 12 volts to the compressor is because they were too cheap to fix it right. I suppose they had a switch to turn on the compressor. Lucky that the system didn't blow up.

Don't think the DME is fried if you have a high side trouble code and the compressor is not turning on. The DME is doing what it was designed/program to do and that is to shut power to the compressor if the high side is too high.

Did you buy a genuine BMW part or an aftermarket part?

I bought it from pelican parts and it has the bmw stamp on it. However, it was smaller than the original ( socket size needed to remove/install). The part number was not bmw's, I believe it was OEM brand.

I checked the pressure with the compressor OFF and I got 85psi on both the high and low side. Still the compressor wasn't getting any signal to turn on..not even for a few seconds. I'm starting to think I got a defective or wrong pressure sensor.

Just a quick update...I replaced the ihka ( climate control) and everything works perfect now.

Thanks for coming back and reporting the fix.