Carmen: Your problem is an obstruction in the hot water tap, do the following, disassemble the shower handle, with a cross screwdriver, close the main water supply of your house, turn the tip of the tap as if the you will open, and with a 5/8 die, disarm the center of the key, then open the main supply of your house and let the water run a little more or less 20 seconds, close the supply again, check how is the rubber of the tip of the piece that you disassembled and if necessary change it, open the cold key a little and let water run again (that goes out through the hot water pipe) if it has already been rearmed and ready greetings comments