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| 01-10-2026, 07:33 PM | #1 |
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Intermittent A/C
Hello,
I've been stuck trying to diagnose some A/C issues with my 2009 BMW 128i. I notice my A/C fails to cool when the car is idle, likely because the fan doesn't kick on even when I press my A/C button. I've manually turned on the fan via Protools and DME controls, so I know the fan is working -- and it kicks on when the motor temp gets too high I think it triggers at 115-130degC. I went to a mechanic to fill up the A/C system to the correct levels and even replaced the expansion valve just in case something was going on there. Haven't noticed any leaks and over the course of several months I have no reason to believe there are any leaks since the pressures haven't changed much on the low side (a/c was filled in the summer when temps were close to 40 degC). I have a UV light and have not seen any leaks in the engine bay. Leaks may be hard to spot with the evaporator but I still have refrigerant in the system and the high side holds pressure throughout the months. Now, I tried to document all my findings today with the following gauge readings: Outside Temp: 14deg C. Car turned off gauges connected (no e-fan, no a/c) Low-65 psi High-80 psi Car running (e-fan running, a/c) Low- 45psi High- 150-175psi (then fan kicks off and drops down to about 125psi, low side climbs as this happens). I have also attached a video showing what happens. Would appreciate some insight here, this has stumped me for months. I don't know if I should consider a new compressor (because it kicks on when I activate my A/c and pressure builds). But something is not allowing my high side to build up pressure past 175psi or so (is this because of a faulty pressure sensor?)| Video showing the issue below: https://youtube.com/shorts/mN7pfRYx7aA?feature=share |
| Yesterday, 11:22 PM | #2 |
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I checked the pressures again today it was a little warmer.
Ambient Temp: 28deg C. Car turned off initial reading: High:125psi Low:~125PSI Car running A/C Turned on,E-Fan running: High: ~175PSI Low:55psi Car running A/C off: High: ~150PSI Low: climbed to 85PSI Turned A/C back on: High:150PSI climbed to 175-180PSI Low:55PSI A/C Still on, sprayed condenser with water High :~150psi Low:~45 PSI Last edited by vize128i; Yesterday at 11:24 PM.. Reason: spelling |
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Appreciate
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