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A/C Issues

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We just bought a 2000 323i and it is our 1st BMW. Here's my issue: the a/c works and is cold when the compressor turns on. It will work sometimes and other times it will just blow hot air since the compressor is not turning on. The dash temp (which reads -40) displays & I thought this was the outside temp. Could this incorrect reading be causing my issue? We have switched it from manual to auto and get the same results. I read other threads and the the dial between the vents are set reflecting 3 blue dots, we know the a/c can get very cold, the compressor does turn on and off. Any help would be GREATLY appreciated.
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Potentially? I'm not sure how the ambient air temperature reading influences the operation of the A/C, but you could start by replacing that sensor or at least checking it for connection. I know there is one on the passenger side, under the front bumper.
I bet ur RIGHT!

When we bought this car, we had to replace the fog lights (& other stuff stolen). When my husband was hooking up the fog light on the passenger side, he also found 2 loose wires dangling. We didn't know what they were for. I believe he said one wire was green and one was green with a white stripe. Are these the the wires the sensor needs to be affixed to? If this our problem, what is the proper term for the item I need to purchase? Thanks so much for your help and speedy response. It's HOT in Georgia. :)

In further reading on the forum, another had my same problem & replaced the ambient sensor and the a/c began working since the car thought it was -40 degrees outside & wouldn't allow a/c to come on. They said their sensor was on the drivers side but read it could also be on passenger side. Are there different sensors on each side of the car?
Those wires are for the ambient temp sensor. Get the sensor and connector and all should work well

Sent from my C771 using Bimmer App
One more question

We also found wires hanging down in the same area on the passenger side as well. They to were cut. Can you tell me what they are for & what I need to purchase to fix this as well? Do you recommend any certain website to purchase the replacement parts?

Thank you so much for your help.
Figured it out

I ordered my ambience sensor, connector, & extra wire from This is placed on the drivers side.

The wire on the passenger side are for the thermostat sensor for the heated jets for the windshield wipers. Thank goodness I kept reading the forum & answered my own questions.
Thanks Everyone

My husband installed the ambience sensor & the correct temp illuminated in the dash & most importantly, the A/C came on and chilled me to the bone. !!!'. Who would have thought an outside temp sensor would cause the a/c not work???? Totally crazy.

Thanks to everyone who posted.......
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