5600 Overheating in winter

[JuneauAlaska]

My toolcat 5600 has overheated a few times this winter. Temperatures ranged from 30 degrees down to 0 degrees. I came to work and the battery was dead. So I jumped it. I let it warm up for about an hour. I drove it around the property for about 10 minutes in mid idle I throttled it up for a bit and continued to drive. And then it started to beep and my heat gauge went to red and the shut the machine off. My coolant level is good and the fan seems to be working fine. Im looking for help.

 

[SSdoxie]

Radiator fins plugged so no or little air flow? Thermostat sticking? First 2 things I would check.

 

[JuneauAlaska]

The machine went to the shop for its 1000 hour service. They found that the sensor was wrong. Everything is working great... knock on wood.