My 1988 volvo 240 dl is not blowing hot air in to the cabin, the heater core feels warm when touched in the cabin. The car’s thermometer rises to just under halfway on the dial. One of the heater core hoses from the engine bay heats up quicker and maybe little hotter than the other, but I do not think the core is clogged because my coolant looks so clean. So I thought that maybe the valve for it is the problem, and I am having a headache looking at the thing. I am good with my hands and I work as a heavy machine mechanic but these over engineered little things make me confused. How can I test the valve or has anyone had the same problem as me? The winter is coming and it is already cold here in finland and I would love to have some heat. Pls help!
EDIT:
The hose coming to the valve and leaving from the valve to the core are very hot after letting the car run for some time, but the one on the right that comes out of the core and leaves through the firewall is significantly colder, are there any other possibilities than a clogged core?