Shouldn’t have offered to fix the HVAC system

I am the maintenance person at a big corporate office building.

I check all of the equipment and construction areas, and I have to make sure everything is working.

Most of the work that I do has to requires very little certification or specialty because I have so much that I have to remember. Typically, I don’t mess around with large equipment like HVAC units. Air conditioners and heaters are definitely above my head, and my boss hires an HVAC technicians to come to fix the heating system. However, when the heating system stopped working last week, I looked at the HVAC unit and the process didn’t seem that hard to do. The part that was broken on the furnace was very clear, and I told my boss that I could probably fix it without the help of an HVAC worker. I was able to fix the heating system, and my boss was so happy. However, ever since, my boss expects me to fix all of the air conditioners and heating systems. I have tried to explain to him that I was only able to fix the heating system that one time, but I don’t understand how all HVAC systems work. He insists that I will be able to figure out how to fix the air conditioners and heating systems. He has even threatened to fire me for not wanting to fix the HVAC units. He is just trying to be really cheap because HVAC workers are more expensive than I am. They get paid to work on HVAC systems, but I get paid much less than HVAC workers. I should have never offered to fix that HVAC system in the first place.

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