have a 95 ranger grate a/c heater sucks in the winter new thermostat, heater control valve, heater core, and flushed the entire system. what next?

Does the engine get up to temperature during the winter or does it stay on the cold side? Does it make a difference whether your riding down the road or sitting still? Are you positive the thermostat is the oem temperature? Have you looked at the water pump? Sometimes a weak heater is the sign of a water pump thats on its way out.

i have replaced the thermostat 4 times. last time with one from fomoco. according to the gauge on the dash the operating temp is where its supposed to be. with slight changes from summer to winter but for the most part consistent in the temp. i have flushed the cooling system and the pump seems to be moving the coolant through very well when at opp temp. The only other thing I can think it could poss. be is the blend door is stuck for whatever reason. i have removed the servo motor from the top of the plenum box and it seems to be working properly. but i cannot move the blend door by hand. should i be able to?

Did it ever come up to temp? My 91 Ranger took about 100 miles of summer driving to get the temp needle to TOUCH the normal line. I tried new thermostat (twice) and double-checked EVERYTHING, it was like that since it was new.

yes should move something either fell down into the case or broke

I preach on this a lot.. And it works both ways.. Make sure you are using the right radiator cap.. Too little pressure - it overheats.. Too much pressure - heater does not work well.. The pressure the cap provides in the system alters the boiling point. If the temp does not get high enough to open the thermostat, then the heater does not work well.

true to above answers,but your control switch from cold to hot may be bad.

the rad cap is a 13lb cap according to the mfr this is the correct cap pressure. however it is an aftermarket cap...but new NO CHANGE in operating temp or heater. as far as the blend door motor if i move the selector switch on the dash from hot to cold the gear moves with it. if it is something in the blend door itself how hard is it to get in there to fix or at least properly asses?