A couple summers ago I had some cooling issues and finaly it blew the end out of the plastic tank radiator. So I replaced the radiator with an after market all Aluminum double row model. At same time I replaced the water pump, Thermostat, Aux Fan and both hoses. Ending my Cooling problems.
However ( There's always a However!) When Winter comes around The dang thing wont even get up to temp so I can have decent heat. So I first unplugged the Aux elect fan thinking that would do it. Nope Still no heat..
So Each winter since I take the grill out and duct tape some cardboard in front of radiator to block most of the airflow. Then I Gets Me Sun Heat !!
My first thought was that the over sized radiator was causing the problem. But that's not right. The Thermostat should still maintain the engine temp at normal levels no matter what the radiator was doing right ??
I did replace the thermostat as I said when I had the cooling problems. But now I am wondering if the thing is stuck open or something causing my Cold Feet..It acts normal in the summer, Maintaining the temps at 210* Just as it should. So what do you guys think might be going on....

I will add that even when the water temps do get up around 210 as it should the heat is still not near as good as it should be. I have not actually measured the air temps, maybe I should...

Any Ideas ?

 

just a thought, new o.e t-stat, and a quick flush of the heater core. Worked wonders on mine...
Good luck!

 

Make that a thorough flush of the heater core, hose pipe in the heater hoses changing direction until it runs clean, this may take 10mins.
If your engine is producing hot coolant then you should be able to benefit from it as long as your heater matrix/core is clean. Good Luck