With the truck fully up to operating temperature when their rear climate control is turned to high on heat the air that come out of the vents is lukewarm at best
My car has 45000 miles.
My car has an automatic transmission.
I believe the Suburban has a dual climate control system. This means that the rear of the vehicle has a separate heater core. It is likely that there is a restriction to the rear heater core in your cooling system. It is also possible that the heater control valve is not allowing coolant to flow to the rear which would be a restriction as well. I would recommend having your cooling system inspected by a qualified professional to determine the exact cause of this issue.
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