Check your coolant level.The front heater looses it's warm water first if
the coolant level gets low.If it get too low, the red light will flash to
tell you.Your front heater will blow cold before this happens,but the back
will still work ok(if turned on).Air gets trapped in the place where
coolant should be. You can add coolant by removing the expansion tank cap
(cold engine) and starting the engine.

Use 50/50 antifreeze/water Phosphate free coolant.

If your system has a leak or bad cap,coolant will not be sucked from the
overflow tank,into the expansion tank.Check to see if the overflow tank is
full,but the expansion tank is low.If so,you probably must add it directly
to the expansion tank(engine cold).Maybe do this 3 or 4 times over a 3 or 4
day period to get the heat back.The air will work its way out over time.

More detailed and complete instructions are avaliable in the arvchives to
bleed air and add coolant.Type in "bleeding" or "cooling ststem bleeding".

Signed....Cold Toes