HLS & Service Heater LEDs
Hello.... HLS usually means hi limits.... check the connectors at the high limit switches, to make sure they're not rusting off. If they're good, and the heater fires, but turns off after a minute or two, the problem lies usually with the temperature regulator.... it's the round cover with the 4 slits in it between the inlet and outlet. It comes out counter clockwise. It holds a spring with what would be a car thermostat attached to the end of the spring. That thermostat can be malfunctioning, and it will allow the water to get too hot coming out of the heater, which trips the hi limit. A quick fix is to remove the spring with the temperature regulator, and put the cap back in place. You definitely want to get another one to replace it, because the efficiency rating of the heater will go down considerably.... but it will do the job in the meantime with no danger. (Its like running a car with the thermostat removed, it can be done, but the engine runs too cool). They cost about 50 bucks on amazon.
on Jun 21, 2015