Cooling fan device

A cooling fan device configured to use a cooling fan coupled to an engine via a fan clutch to generate cooling air flow for a condenser for cooling an air conditioner refrigerant, the cooling fan device comprising:

• an electronic control unit configured to control an engagement rate of the fan clutch, the electronic control unit being configured to execute:
• a first calculation process that calculates an air conditioner requested engagement rate, the air conditioner requested engagement rate being a requested rate of the engagement rate in accordance with a cooling request for the air conditioner refrigerant;
• a second calculation process that calculates, as a first guard value, a value of the engagement rate at which a rotation speed of the cooling fan increases at a specified speed;
• and
• an upper limit guarding process that sets a value of the air conditioner requested engagement rate to the first guard value when a calculated value of the air conditioner requested engagement rate in the first calculation process exceeds the first guard value, and
• the electronic control unit is further configured to control the engagement rate based on a value of the air conditioner requested engagement rate after execution of the upper limit guarding process.