Thanks for advice.
I have less than 70 percent marks in my B.E. so I think I am not eligible for masters in Canada.
1.Do you think I will get visa easily if I apply for post secondary course.
If so
I am confused between
Heating and refrigeration technician(HVAC) or
Electrical technician or
Robotics and industrial automation.
Please don't hold yourself back with percentages, search different universities, not just one. Different state universities have different requirements.
I am not any visa expert, I don't know what your visa process will take it to get you a visa. But when I saw your post I wanted to advise you of a course which is better for you in the future and not just visa process.
It looks like you have already made your mind to pursue diploma studies and all of these mentioned are diploma courses:
Heating and refrigeration technician(HVAC) or
Electrical technician or
Robotics and industrial automation.
From my understanding, HAVC technician is totally different than an Electrical technician and
Robotics and industrial automation.
In HVAC technician your job would not be office job it will be more service type of job where you have to do lots of physical work, its good money but its lots of hard work, it may be good for you if your a person who likes to work with physical requirements and have interests in understanding of fridge/refrigeration/heating/cooling/units.
The electrical technician/technology is a very vast field, you may end up working physically on wiring DC/AC units could be household units/construction/industrial units or you may end up working in an office for drafting and designing units wiring on AutoCAD or PLC troubleshooting. BUT you will always work with the main lead engineer. You will never become a lead! keep that in mind.
For Robotics and industrial automation again, you will work under the supervision of the main Engineer, you may have to work on drafting AutoCAD drawings in an office environment or you have to solder small electronics parts on PCB board in a robotic chip Cricut environment. If you are lucky you may also get a chnace to work on robot programming maybe Python/Java/C++ but its usually the lead Robotics Engineer who does that you maybe just do trouble shooting for him/her.
You may also end up in an industrial physical working environment where you may also do physical wiring or process control tasks on industrial units.
Hope these clear some of your thoughts.