Originally Posted by speedball1
Without being there I can't say for sure but if the heater hasn't been flushed on a regular schedule it can develop mineral build up. If this gets into the hot water system it can clog up the inlet ports on cartridges and the seats on faucets. Shut off the supplys and open up a valve and remove the cartridge and then turn the hot water supply back on to see if hot water's getting up to the faucet. Also to check to see if the tank is pressured up, lift up the lever on the T & P valve. Water should come out under pressure. If not then there's a problem in the cold water supply. try all of the4se and get back to me with the results. Good luck, Tom