Broken HVAC switch leads to furnace not turning on

The seasons changed very fast this year.

It went to 90 degree days to 40 degree nights over the course of 24 hours.

When I went to change my thermostat from air conditioning to heat, it didn’t change. The air-conditioner stayed on. Cold air continue to pour out of the vents and I could hear the compressor kicking on just the same as I did before. Clearly, it was time to call out the professionals. I didn’t know who to call or where to start. I didn’t know if I should call the heater or the air conditioner repairman. I looked it up, and I discover that they are all one and the same and they go under the title HVAC repair. An HVAC repairman was able to come out the very next day and he explained the situation. It seems that there is an internal switch inside my heating and air conditioning system that tells the system to turn on the heat or to turn on the air conditioner. It all depends on what I set the thermostat to. The problem is, that the switch was broken inside my system. This resulted in my system being stuck with the air conditioner on, regardless of my thermostat settings. Because my HVAC system is so old, the technician had to order the part. I guess I will have to make do with a space heater for a few nights. I just hope it doesn’t get actually freezing before the switch arrives and he is able to officially fix my HVAC unit.