Hi guys my heater using working in the mighty au
Only seems to wanna blow cool air
Have tried...
Draining cooling system
Refilling and bleeding air out
Check heater control valve ,heater tap.
Thermostat
Quite puzzled where to now have check the vac line behind the dash and seems to be working and is connected
Need me heater in these freezing months of winter here in kiwi land
Any ideas

DO you have any water leaks in the cabin? might want to flush out the cooling system also.
Heater cores did stuff up a bit on AUs

No water leaks and have flushed system also

I have fixed cold air blowing problems twice once in my ef and once in my el just by putting in
new thermostats.
Worked for me might be worth a try ?