HiCustomer Thank you for asking your question on JustAnswer.
The problem is likely a faulty temperature blend door actuator.These are common components that fail and cause no heat issues.The actuator is located on top of the heater box behind the dash and will require dash removal to gain access to it to replaced it.
Here are some instructions that may help.
Temperature Blend Door Actuator
Removal and Installation
Remove two bolts and reinforcement from under steering column
Pull up to unsnap upper finish panel and remove