Hello,

I have a Robertshaw Thermostat, item # 9520. It has started making a clicking noise, rather rapid click, click, click, on and on. Have changed batteries but still does it. The clicking sometimes last for several minutes. Can not see anything clicking nor can I tell where it is coming from.
The blower will start and stop a couple of times while the clicking is going on, but the A/C will operate, what seems like, normally during the clicking cycle and even when the clicking stops. The clicking will stop for a random time and restart at a random time.
While typing this I noticed the thermo will not turn the blower off now.

Any ideas on what might be wrong?

Thanks,
Buddy

Sounds like the thermostat bought the farm unless you have less than 24 volts feeding it. A lower voltage will cause a thermostat to malfunction.