1995 Ford Ranger heater

Was the problem there before or did it just start after the parts replacement? If it just started, suspect an air pocket in the heater core or under the thermostat. Check how hot the hoses get. They should be too hot to hold onto for very long. If the upper radiator hose gets hot, coolant is circulating past the thermostat so bleeding it isn't the cause. Check the coolant level. If it's still low, it won't circulate through the heater core.

If the heater hoses are hot, you have an actuator problem with the heater box. That was a real common problem with '97 models. I don't know if that goes as far back as on a '95.