AC thermostat in apartment sparking when temperature is adjusted?

Question

The AC system in my apartment keeps short cycling and whenever I adjust the temperature while its cycling the thermostat actually gives off a flash. I live in a large apartment complex so the maintenance guy is probably not going to get to it until next week. I've got the unit switched to off for tonight but I live in Alabama and its supposed to be close to 100 this weekend and the apartment design doesn't leave much ventilation so I really can't stay here until it gets fixed. What could be wrong with it? The system is about 20 years old.

Answer 1

Scorpio is correct.Are you or were you getting some cooling?

Don't be afraid to use it if needed.No danger of being injured.

Answer 2

If it is a mercury switch (a small sealed glass tube with liquid mercury inside), it is completely normal. The mercury is the conductor and it is attached to a bi-metal (a metal that changes shape with temperature). It is normal to see a spark when the connection is made. Normally, we don't stare at it and notice but if you happen to be in a dark room, you may see a flash. http://home.howstuffworks.com/home-therm...

Answer 3

I agree with scorpio, you just seeing the flash inside the mercury switch.

The thermostat wiring is only 24 volts. That is not enough voltage to create hardly any spark with a short like when you are touching two bare wires together. For some reason it is more visable in the mercury switch.