pl. let me know how to create a point history probe so that the probe can record the maximum and minimum values of another blockage object during heating cycle

Create new object and change type to "point_history". Put this object to blockage region. After calculation see result-file.

thanks for ur response! and i m already doing as u said but my problem is that how to use this point history probe to record the maximum or minimum temperature throught out the blockage object for the whole time of simulation, the probe shld only concerned with the maximum and minimum temperature locations of the blockage object. pl. suggest

Try to use In-Form

Some ground coding acting over the appropriate object patch to record max and min values for each cell in the object would be my approach.