Heating problem
 

Can anyone help me ive got a problem with my heating system?

it blows hot air first thing in the morning, when you stop for a while it will not blow hot air again until the next morning.
We have changed the thermostat, checked the pipes at the firewall and they are both hot.
Can anyone help me out

the flap or damper which manages the cold or hot air maybe to clamp.

my supra used to do the same thing every morning (before my sister totalled it), you could turn on the car, leave it running for hours, and it would still be cold. for some reason, it will only warm up after you've started driving the car

it could be the solonoid under the heater control unit gone faulty... haven't had a lot of experience with those failing here

for the post directly above me... your problem was low water ;)