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Old 08-07-2018, 12:17 PM   #1
rumatt
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Let's play a game - diagnose my E46 AC problem

E46 AC blows cold... most of the time.

Sometimes there are issues with fan speed. The auto mode just doesn't boost the fan as high as is needed, so I turn the thermostat from 70 down to low 60's... The fan kicks up and it gets nice and cool.

Yesterday the air being blown wasn't cold. I lost all cooling and it was blowing warm air. I had to ride the rest of the trip windows down.

This morning it's working perfectly again.


Last edited by rumatt; 08-07-2018 at 12:35 PM.
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Old 08-07-2018, 12:22 PM   #2
wdc330i
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We had a similar problem in our E70 X5. It was repaired with this part, I believe (final stage resistor):

http://www.bimmerworld.com/BMW-Inter...6923204_2.html
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Old 08-07-2018, 12:38 PM   #3
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Interesting. What were the symptoms on yours?

And the fact that yesterday the blown air turned warm. And it fixed itself by morning. I don't get that.

But there are some nice how-to's on youtube. I could just try it... although it looks like a bit of a pain in the ass.
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Old 08-07-2018, 12:53 PM   #4
John V
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The final stage resistor should not affect temperature from the vents.

It sounds like you have a low charge. To diagnose, need a tool that can do live scanning of the AC system. Or start with a system low side pressure check. It could also be a compressor clutch getting worn. When they get hot they stop engaging. If possible, when the air goes warm, pull over and see if the compressor is spinning or if the pulley is just spinning without turning the compressor.

At the mileage your car has I bet it's the compressor clutch.
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Old 08-07-2018, 01:05 PM   #5
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I was thinking something along the lines of what JV said. Does it stop working after operating for a while?

It sounds as if something is heating up over time and eventually affecting function. Was the car parked in the sun for a while the time it did not work, but not on the days when it worked?
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Old 08-07-2018, 01:38 PM   #6
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Quote:
Originally Posted by FC View Post
I was thinking something along the lines of what JV said. Does it stop working after operating for a while?

It sounds as if something is heating up over time and eventually affecting function. Was the car parked in the sun for a while the time it did not work, but not on the days when it worked?
It only stopped working once. And it was hot as hell and it had been running for 45 mins.

I guess I have both problems. (odd fan speed and compressor clutch)
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Old 08-10-2018, 12:25 AM   #7
Terry Kennedy
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Quote:
Originally Posted by rumatt View Post
Sometimes there are issues with fan speed. The auto mode just doesn't boost the fan as high as is needed, so I turn the thermostat from 70 down to low 60's... The fan kicks up and it gets nice and cool.

Yesterday the air being blown wasn't cold. I lost all cooling and it was blowing warm air. I had to ride the rest of the trip windows down.
The FSR only affects fan speed (and it hasn't been an actual resistor in years - it is a Darlington transistor array).

This could be a large number of things, but I suspect the IHKA (Irritating Heating Kooling Artifact, according to Tech Talk, who prefers manual controls) based on the combination of incorrect fan speed and random un-requested changes in temperature. Other possibilities are the duct flap actuators or something in the refrigerant system (low gas or bad clutch, as mentioned elsewhere).

I have a pre-coded E46 IHKA if you want to borrow it to see if things get better. You need a coded one because the ones you get from the parts counter sit there completely useless, displaying "NC" (Not Coded). Coding just tells it if it should operate in degrees C or F mode and if the car is a diesel or not (the "bad air detector" that auto-switches to re-circulate is disabled on diesel cars).
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Old 08-10-2018, 08:24 AM   #8
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Quote:
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It only stopped working once. And it was hot as hell and it had been running for 45 mins.
OK, so that jives with what I said. Really hot day, working hard for a long time, something overheated and it quit on you.

That doesn't sound to me like a low charge. Sounds more like overheating. Maybe heat is not being properly dissipated and over time a sensor tripped. Or the high demand caused to much heat build up (due to friction) and a mechanical component sized or a sensor's high-temp limit tripped.

I realize none of this helps you.
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Old 08-11-2018, 12:08 PM   #9
Terry Kennedy
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Quote:
Originally Posted by Terry Kennedy View Post
I have a pre-coded E46 IHKA if you want to borrow it to see if things get better. You need a coded one because the ones you get from the parts counter sit there completely useless, displaying "NC" (Not Coded). Coding just tells it if it should operate in degrees C or F mode and if the car is a diesel or not (the "bad air detector" that auto-switches to re-circulate is disabled on diesel cars).
The aforementioned IHKA:



64-11-6-956-319 US MSRP $832.62, GetBMWParts $679.42.
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