2002 ford explorer

my ford explorer blows out cold air until i drive…vehicle temp is at optimul running temp but still blows cold air till i drive why???

Did you check the coolant/antifreeze level? Check both the reservoir & the radiator (not while hot!)

Any service done on the cooling system lately? Run low on coolant at all. You may have air in the cooling system.

Vacuum leak.

The air temperature blend door is electric, not vacuum.
This is most likely a coolant issue, as was suggested.

Add a second vote for low coolant. YOu probably have a leak. What year and what engine?

Could also be a bad thermostat. If it is stuck open or weak, this is a classic symptom.