Hi. first feel both heater hoses to ensure that coolant is flowing through heater core. Both should be equally hot. Next is to check heater control function. Does it work in different modes, do you hear anything when you switch from hot to cold. Possible the flap controlling the air temperature is stuck or broken, the flap is called a blendoor. Look at all the parts under the dash for the heater and ac system and if nothing is broke or undone and both hoses are hot then you need to take it to a shop and tell them that you have a blendoor problem.
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