You may have a vacuum leak
it sounds like your ignition switch, i ran into a similar problem, your power goes through your ignition switch for your blower motor.
A malfunctioning blower motor resistor will cause the blower motor not to work. When the resistor is bad the blower motors will not turn on.
Most likely cause is a failed blower resistor.
neither,blower resistor or blower module controls fan speeds.
Check the fuses first and the blower relay.
Blower motor NG. Blower motor resister NG. Blower motor fuse NG. Blower motor switch NG.
The following can cause this problem.................. 1. Bad blower motor. 2. Bad blower motor wheel. 3. Trash in the blower housing...
If the blower runs on high it will get hot. If the blower is wearing out this will cause it to get to hot and blow.
A common cause for this is a burned out blower resistor. Tech JK --------------------------
Do you mean the cooling fan? If so engine temperature has excedded 235 degrees Check coolant level
The usual cause is a failed blower motor resistor.