The temperature of my shower goes from very hot to very cold. I have looked at the controller and found the spring to be quite stiff, could this be a defective thermostat? If not, how do I solve this hot and cold shower problem?
Does this temperature fluctuation occur on its own while you are showering, or when you are trying to adjust your water temperature before you get in? Normally extreme temperature variation is caused by a bad stem/cartridge.
The temperature fluctuates when in the shower, and does this by itself, without anyone touching the temperature control or water flow control, and no other water is being used in the house.
It sounds like there may be debris in the shower valve…remove the cartridge/stem (after shutting off the water), close the shower door and turn the water main back on for a count of 3. Shut it off, put a new stem/cartridge back in valve, turn water back on and test. That should solve the problem.