2006 range rover sport my heater is blowing hot from drivers side but only warm from passengers side. Also getting low coolant but plenty in the expansion tank. Could it be an air lock??? New alternator.
Gearbox flush.

Coolant tank replacement is common on these to stop the warning message.
The float inside sticks. £25

Could be a blocked heater matrix causing lack of heat

How do you unblock it ?
Does it involve taking the car apart ?? New alternator.
Gearbox flush.

it can be attempted under the bonnet, by disconnecting the small water pipes on the drivers side, and stuffing a hose pipe into the end.

If that fail, matrix need changing

New matrix required. You won't unblock it unless your extremely lucky, or patient

Go to a refrigeration suppliers and by a gallow gun and a pack cartridges, be careful as they apply a lot of pressure fast if it can be unblocked that will shift it, were glasses/googles as if something comes out it will be coming out fast.