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10 days ago when I sent you pictures the voltage was 1.2V and it didn't work. now i don't know if this is a coincidence or it's really too low voltage

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Quote:

Originally Posted by andrewwynn (Post 1210787)

Pressure sensor 0.9v. It's pretty low on the scale, what does that read when temp is hot and AC runs?

I don't know what the normal voltage off the press sensor is. It's not a simple on/off switch it sends a voltage to the brain that figure out the actual pressure. If it reads low incorrectly, it may allow operation as ambient temperature raises the pressure inside so see what is the voltage on the pressure sensor when it works and maybe watch real-time the ECT as well to see the exact temp where it magically starts working.

Checked my notes from when I was debugging my aux fan (turned out that was the one and only problem, so my AC, pressure sensor, ECU, etc. were all good for this data):

2001 3.0i

"AC Pressure sensor - in AC line very close to the lower radiator hose. Measured in Foxwell:
Ignition ON, engine stopped, AC off, cold: 1.25V
... connector removed: 5.00V
Engine running: 1.24V
Engine running, AC on: 1.76V, rising
... connector removed: 5.00V"

Now I started the engine and the air conditioning no longer works, the voltage is 1.2V, then I gave the gas twice to about 3000rpm and it worked and the voltage is

Quote:

Originally Posted by PalmSpringsE534.6 (Post 1210780)

Start your engine...go to the radiator output temperature sensor (on the lower radiator hose) and then disconnect the connector. The fan should start right up. If not, replace the sensor. If it does start right up, then do the same test with the AC pressure sensor.

The fan does not start up when I pull the sensor off the coolant line. So I guess my sensor is toast. Time to drain the coolant and replace it. :(

Now it behaves differently (maybe because it's colder outside) Basically, the air conditioning voltage is 1.8V and I turned off the air conditioning on the button the voltage drops to 1.2V. I press the button again to turn on the air conditioning, the voltage remains 1.2V and does not work, then I give the gas up to 2500-3000rpm once and the voltage goes to 1.8V and the air conditioning starts working

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It would appear the sensor is working and sees enough pressure. You need to confirm if the clutch is engaging when you press the snowflake. Symptoms suggest the clutch is not grabbing

How, to listen just under the hood or?

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You can see the compressor from top side. Have someone push the A/C button on and off. You should hear it click. Plus notice RPMs change. On other vehicles the clutch will engage with the engine off. I'm not sure about BMWs.

Watch the clutch while somebody presses the snowflake. Take a slomo video even better.

It can be tricky to see the inner part spin since the outer pulley off course always spinning.

Also: in software you should be able to read status of the clutch.

I suspect the clutch air gap is off and not grabbing or variable displacement compressor is stuck at zero displacement until you rev.

You need to figure out if the clutch is grabbing

Problem with A/C

The clutch catches when I turn on the snowflake
Aux fan not work
https://youtube.com/shorts/kVLFzk-FyRk?feature=share

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