Are thermal fuses polarized?
Short:  No. Thermal fuses are not polarised.



Longer :-) :

No thermal fuse I have ever seen was polarised (based on decades of experience but ...).

I cannot think why a thermal fuse would be polarised.

This seems to be extremely unlikely but I mention it for completeness:
 If a device that was called a thermal fuse WAS polarised then it would be more than a fuse - it would be very special in some unusual manner.
 If so then it would need to be replaced by an identical unit if it was going to do the same job. 



A photo would be a good idea.
 Does it have a part number on it?