Bmw x5 4.4 - no heat !
Here's what I found out. The X5 4.4 has a secondary water pump and should have a heater valve located near the rear of the engine. Check the heater valve and hose and consider replacement.
I checked my Bentley Manual also and here is what I found about the heater valve replacement:
1) Drain engine coolant. Allow the engine to cool thoroughly before opening or draining the cooling system.
2) Working in engine compartment at left strut tower:
* Detach electrical connector at heater valve;
* Loosen hose clamps. Pull coolant hoses off valve.
Use shop towels to catch dripping coolant
3) Pull heater valve out of rubber mounts.
Installation is reverse of removal. Remember to:
* inspect hoses and rubber mounts, replace as necessary. Use new
* fill and bleed cooling system
TIGHTENING TORQUE: Coolant Hose Clamp 32-48 mm (1 1/4 - 2 in)
2.5 Nm (22 in-lb)
Source: Bentley Publishers.com BMW X5 Service Manual
I am definitely going to check this out.