no heat just cold air

Hi everyone i have another problem .When i turn on the heater only cold air comes out ,even if i let it warm up for 5 minutes .It only gets hot air when i drive and when i am stoped at a light it starts to cool down,what can cause this. Thanks

Check your coolant level, It may be low and there may not be enough circulating when at low RPM sitting at an idle.

Just a thought

Check your coolant level, It may be low and there may not be enough circulating when at low RPM sitting at an idle.

Just a thought
Hi! i checked my level and it's ok ,but i'm thinking could it be it has to be changed ,the fluid is long life (the orange one) i have it in there since i have the car i bought it used in 1998 and it's a 96 model