E46 Fanatics Forum banner

FSR, Blower or Ambient Temperature Sensor?

9K views 10 replies 9 participants last post by  ijdetoro 
#1 ·
I have a 2002 330ci, and about two years ago I had to replace my ambient temperature sensor as I noticed that the external temp reading was going crazy from -40 to +122 and the A/C wouldn't blow cold air. I had it done at a BMW specialist independent shop, and I ended up getting ripped off for over $500.

A week ago or so, the external temp reading started going crazy again, but ended up settling at +122, and the AC worked ok as long as it stayed at that reading. The sensor appears to be in good shape looking from the bottom under the bumper.

Today, the A/C stopped working completely. No air whatsoever coming out and the blower does not seem to be on, but the controls on the dash seem to be on and working correctly. I checked the fuses and they are fine. The temp. still reads +122 degrees.

Would a faulty sensor be cause for the blower to shut down completely, or do I need to install a new Final Stage Resistor? I have seen that mentioned frequently here, and it seems it could be the problem. But I also have the faulty temperature readings. Should I just order a new FSR, or should I take the bumper off to check the wiring of the sensor more carefully? Is that how thats even done?

Any opinions would be greatly appreciated.
 
See less See more
#5 · (Edited)
Temperature Sensor Issue - 122 F

Did you ever find the cause of the problem. I am having the same degree reading and did change the sensor. No change. Appreciate any feedback
Me too. My ambient temp sensor was torn off due to a minor accident I had which ripped out the driver's side fender well [where the sensor is located]. While the sensor was off, I had driven around for about a week and had readings of -40 F and +122 F - mostly staying with +122 F but switching every once in a while. After completely re-wiring the sensor back in, I now have +122 F exclusively - the reading never changes.

I have tested the sensor itself by checking resistance across it, and I see that it is functioning properly. I have also tested the wiring from the sensor all the way back up to the instrument cluster control panel (connection X11176 ports 1 and 2) and I have no shorts whatsoever in the entire circuit, yet my car still reads 122 degrees F!

WTH?? I am at a complete loss. When I test resistance across the sensor, all the way back through the wires, I get the same reading. It is currently less than 32 degrees outside and the OHM meter is reading around 10K OHMs. If I hold my hand on the sensor, it warms up and the resistance shows about 20K OHMs. This thing is working - no shorts. SO, the only thing I can think of is a) the temperature sensor somehow is shot or b) my instrument cluster control module is shot, or c) there is SOME type of "reset" that needs to be performed.

I have spent a considerable amount of time researching this issue but have come up empty-handed. Any ideas?

Thanks in advance,
Tony
'02 E46 M3 SMG
 
#6 ·
I purchased a new temperature sensor from Bavarian Auto and have the same results. No luck. I honestly think that I might have shorted something out within the circuitry inside the control unit - which is, as you might realize, part of the instrument cluster.

As I mentioned earlier, I have tested the resistance of the temperature sensor all the way back to the actual plug on the instrument cluster and I get proper resistance (which changes if I heat up the sensor) all the way through.

I am going to try to disconnect my battery tonight as a few others have suggested, to see if this does the trick. Wish me luck.
 
#7 ·
I just finished fixing the sensor on my mom's 05 330ci. It was ripped out from driving. I started with two open wires, a repair kit from bavarian autowerks, and a new external air temperature sensor. i started out by intertwining the wires from the kit with the wires from the car and then taping them shut (not using the plastic tubes from the kit). then i took the other end of the white wires and inserted them into the grey housing that would connect to the sensor. At this point the problem with a 122 degree reading still remained. so what i did which solved my problem was i threw out the grey housing and i connected the two ends of the white wires directly into the sensor and long and behond i was relieved to see the 122 degrees gone right when i turned on the car. I hope this helps anyone having this issue.
 
#8 ·
does anyone know where to wire the sensory up to? seems as though my wires are gone there are no exposed wires. also when you put the new soenor in did you start the car?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top