hi... i need help my 93 300se has no interior heat, any ideals what to check for first, also my upper water hose is tight with pressure will a monovalve do this type of thing or heater core or something thanks for the help.

I'd try un-plugging (electrical connection) the "duo-valve" located behind the drivers headlight. Also might try lightly tapping on them with electrical disconnected.

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ok.. thanks for the info.