That is a very tricky question. There are a lot of variables.
If the engine is running and the engine is hot, the heater hose going into the heater core will be hot. If the blower fan is on high and there is hot air coming through the vents, then the other heater hose will be cooler because the heat has been taked out of the coolant.
If the fan is on low or off, there is very little heat transfer, so the other (outlet) heater hose will not be that much cooler than the inlet hose- which is hot.
If both inlet and outlet hoses are not hot, then that means the engine has no coolant flow at all. Even with an engine at normal temperature, and no flow, one of those hoses should be hot just for the fact of heat transfer. So if neither hose is hot with an engine at normal temperature, then there is no flow at all. That can be caused by a blown headgasket or other reasons for air pockets. Air pockets do not let coolant flow.
In the engine does not get to normal temperature, then your problem could just be a bad thermostat.
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