I have changed many engine cooling hoses and tubes myself over the past few years. Recently fitted water pump number 3 (looks like it was actually a failed o-ring on the rear outlet tube). Compared to previous experiences had a hard time bleeding air despite not loosing that much coolant and ended up having to vacuum the system via the expansion tank. A few weeks later whilst trouble shooting air con issues, I discovered the rear climate does not blow hot even at max heat. Checked heater lines and they appear to be cold instead of hot which leads me to think there must be air in the rear lines. Workshop manual does mention anything about bleeding the rear lines.

Anyone here have any suggestions?

 

Solved, I think. Raised front of the truck at 45 degrees and bled the engine compartment rear heater line. Rear climate lines now hot.