I could not figure out what was wrong with the HVAC unit

I literally could not figure out what was wrong with that HVAC unit, and I was afraid that I was going to have to ask the owner of the HVAC company to check out the HVAC unit.

I have been an HVAC technician for a long time, and I have been fixing HVAC units for a long time.

I am the main HVAC service technician at the HVAC company, so when people call our HVAC company because they have a broken furnace or air conditioner, I am the person that they call to fix their HVAC unit. Before today, I have never had trouble fixing an HVAC unit, but today, I had a lot of trouble. Someone called the HVAC company a few days ago and told us that they were having trouble with a central air conditioner. Apparently, they had called another HVAC company before, and that HVAC company sent out multiple HVAC technicians over a period of one week. Apparently, these HVAC technicians could not figure out what was wrong with the HVAC unit, and one of the HVAC technicians recommended calling our HVAC company. I am aware of this HVAC company, and I didn’t think much of it. I figured that I would not have a lot of trouble with the central air conditioner. However, when I took apart the central air conditioner, I could not figure out what was wrong with it. Sure, I could have just started replacing parts, but that would have been expensive and unethical. I spent the entire day looking for the problem, but I couldn’t think of it. I thought that I was going to have to call my boss, but I would have definitely gotten yelled at. Finally, I figured out the problem, and it turned out to be super simple.
HVAC system