07 XC70 driver's side blows warm air with A/C on Topic is solved

Post by **br0dy519** » 19 Jun 2023, 17:55

Did you check the pressure to see if it was low on refrigerant charge yet?

Post by **vtl** » 19 Jun 2023, 19:21

Both low and high pressure can lead to warm air out of vents.

Post by **abscate** » 19 Jun 2023, 19:26

Incorrect charge can put a temp gradient on the evaporator and cause the side variation in temperature. BMW really sees this with a small charge loss.

Post by **erikv11** » 19 Jun 2023, 20:36

Thanks for replies!

I did check low side pressure initially, before even posting. I it was like 27 so I wrote it off, thought it was about what i normally see on my P2's with this gauge. But I'll get a careful reading and report back.

Post by **vtl** » 20 Jun 2023, 06:14

You need dual gauges for both low and high sides. Also a thermometer, high side pressure depends on the temperature. Once I got a dual gauges set, I'm able to fill the A/C on my own. Oh, I also got an A/C vacuum pump.

Post by **erikv11** » 20 Jun 2023, 07:41

Noted, thank you. I'll check them both as I have a dual gauge set too. Harbor Freight but it works. Haven't splurged for a pump yet I have been borrowing one from FLAPS.

Post by **erikv11** » 20 Jun 2023, 21:24

Engine warmed up, AC compressor running with fan on highest setting.

Permission to charge, captains?

Post by **vtl** » 20 Jun 2023, 21:32

75 F, 15 PSI low, 135 PSI high? According to internet charts, R134a at this temperature should be 35-45/150-170 PSI. I would add a bit and see how it goes.

Post by **erikv11** » 20 Jun 2023, 22:15

Was checking psi as it charged and ended up finishing off the open can I had, about 8 oz (2/3 of a can) added overall. Definitely colder now on the driver's side so a big improvement but it still seems warmer than the passenger. We'll see how it holds up under demand. Readings are now 32/175 at 75 F.

Is it peculiar that the static pressure (engine running, AC not running) readings are not the same on low (65 PSI) and high (100 PSI) side? Seem too far apart to just reflect gauge (in)accuracy.

Post by **vtl** » 20 Jun 2023, 22:51

erikv11 wrote: 20 Jun 2023, 22:15 Is it peculiar that the static pressure (engine running, AC not running) readings are not the same on low (65 PSI) and high (100 PSI) side? Seem too far apart to just reflect gauge (in)accuracy.

The high/low temperatures are different, so vapor pressure is different. But high side will eventually boil off and expand to the low side if left undisturbed.