Grohe shower faucets have a temperature control dial installed on the cartridge regulating the handle's rotation preventing scalding and setting the temperature at the desired level. This features can be removed. Since the part sits on top of the cartridge and an adapter is used rotating the cartridge stem setting the temperature, simply remove the dial and replace the handle. This project takes 10 minutes to complete if all goes well.
Find the small screw on the handle's bottom and take it out with an Allen wrench. Rotating the screw counterclockwise removes it. Pull back on the handle to take it off the faucet.
Unscrew both trim plate screws with a screwdriver and pull the screws out of the trim plate. Take the trim plate off. Remove the bracket behind it by taking out the screws in the bracket.
Pull the faucet's cover off. This is the cylindrical sleeve around the faucet's cartridge. It is located under the handle. Just pulling it back removes it.
Slide off the small part on the cartridge's top. This is the handle adapter. Pull the limit stop, which is the temperature control knob, off the faucet's front with your fingers.
Replace the handle adapter by setting it back onto the faucet cartridge. Replacing the sleeve, trim and handle rebuilds your Grohe shower faucet.