AS I froze my ass off during this winter, I had a 97 Sport XJ and it had heat issues but they were only with the blower motor resistor. Michigan had a weird winter where it actually didn’t get extremely cold until about late January and early February. So while doing a gig job merchandising and driving all around, I had to have heat.
So while it was still cold as hell and we couldn’t break out the hose because it would become frozen, but we flushed as best we could.
So that barely helped and then when I had extra money by a miracle my Water Pump went out and I had to with my dad brave the cold and actually do a proper flush. The best thing was that the weather broke and it was in the 40s, which allowed us to break out our hose and do a proper flush. CLR in the radiator and heater core busted out so much rust and rusty water flowed.
The biggest Vilnian in all of this was the heater core in let hose, it was rusted shut and there was zero coolant flowing in and out of the heater core. However, in order to get the part I went to 3 different auto parts store to track down the heater in let hose. So when the water that’s flowing through your radiator and heater core over 20 years starts to clot. Your heater inlet hose rusts and captures all of it and sudden forms a blockage and stops your heater core from being able to function.