I am not an expert, so take
all information and instructions on this page with a pinch of salt. It is
quite possible that they will harm you, your wallet, your car, or all three.
If in any doubt at all, take your car to the professionals. You have been
warned.
Unplug the valve connector (C-K).
Check that +12V is present on pin 1 of the connector (K).
If not, check fuse and continuity of red/green wire from plug (K) to fuse.
On the valve itself (connector C) the resistance between
pins 1 and 2 should be ~13 Ohms, between pins 1 and 3 again ~13 Ohms, and
between pins 2 and 3 ~26 Ohms. By applying 12V on pins 1 (+) and 2 (-) you
should feel and hear the valve operate (close). Same should happen for the
other half: pins 1 (+) and 3 (-). Each half of the valve should draw ~1 A
current. Applying the voltage should stop the windscreen and footwell vents
from blowing hot air.
If the valve does not operate as expected also remove connector
P from the aux. water pump. Disconnect the three water hoses (H). Carefully
lift the guides (G) out of their rubber mounts and remove the valve
assembly. It may be possible to clean and fix the old valve (some people
had success with this), if not replace valve assembly (BMW P/N 64 11 8 374 994).
If you had to remove the valve assembly, remember to top up with coolant and
bleed the cooling system.
If the valve checked out OK, take a look at the control
module end:
Pull out one of the switches in the centre console.
Reach in through the hole and push the A/C control module
out slightly. Grab the module and pull it out.
Locate the blue connector and pull it out by lifting the
white handle.
Press in small white catch and pull off blue connector housing.
Check continuity for yellow/purple and yellow/brown wires
between connector and hot water valve. You should also be able to operate
the valves by connecting these two wires to ground. The connections should
draw ~1A current each.
If these fail, then take a closer look at the wiring
harness.
Otherwise plug the white block back on the control module
making sure that you get the orientation right.
Check that on these two pins there is (with reference to ground) +12V when
highest temperature is selected, and less than 0.5V when temperature is set
to the coldest. If you find significantly different values, then the control
module is probably faulty.
If you find any mistakes or want to suggest additional info
that I should include, please e-mail
me.