Hey all, my heater is not getting very warm. I have added cardboard to the radiator, helped some. I have also checked both hoses coming from the heater core and they are hot. I just picked this truck up from my dad last week, so I will have a lot more questions, but since it is COLD in Wyoming right now, heater is next priority. Any ideas?

1979 F250 Ranger Lariat 4X4 , 400 6.6L, no factory a/c.
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