Low on coolant, stuck open thermostat, plugged heater core, faulty temperature blend door,
You are low on coolant to the heater core.
Could be the Climate Control Unit or Clogged heater core.
If the car is setting in the sun.Heat builds up in the ducts. With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!
The heating system doesn't get heat until the car warms up and the thermostat opens.
Check for low coolant
Insufficient amount of coolant or thermostat not opening
it has to heat up, just like water has to warm in the faucet.
Low coolant. If the coolant is low then the heater core is not able to transfer heat in to the car.
Do you have a heat pump or Gas Furnace? With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!
the blown head gasket would make it over heat. but it wouldn't cause the heater to blow cold, it should actually blow hot if that is wat happened
thermostat is stuck With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!
Could be, low on coolant, stuck open thermostat, plugged heater core, faulty temp blend door actuator,