Toyota Repair: 1993 toyota pickup truck, toyota pickup truck, radiator shop

Question
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Followup To
Question -
I have changed the radiator, thermostat, hoses, water pump, flushed the system and the trucks temp runs where it is supposed to be. when the ac is on the temp gauge doesn't move. When I put the heater on in the mornings, if I don't have the heat on hot and the fan on high the temp gauge goes up over the 1/2 way point. If the heat is on hot and the fan on high it stays at the 1/4 point. The truck is a 1993 pickup, 4 wheel drive, 4 cyl engine, 5 speed manual transmission and has 155 thousand miles on it.
Answer -
It's simply a coolant circulation problem, there is a restriction in the radiator, you can try removing it and having a radiator shop open it and clean the core(this is called a rod out) they may then inform you whether it's serviceable or not and if not the radiator needs to be replaced, or you can bypass all of that and just purchase a new radiator and install it, you don't need to get one from the toyota dealer the aftermarket units work just fine and we use them all the time.

Ted, thank you for answering my question. But if you look at the first part of my question , I put a new radiator in the truck. Could a clogged heater core be causiing this problem?
Thanks
        Rick

Answer
Sorry, my mistake about the radiator, A clogged heater core would not cause the overheating it is not a part of the cooling system other than just provide heat to the passenger compartment, even with the heater completely disconnected the engine should run at normal temperature so the heater can not cause the problem, from what I'm getting so far is that if the heater is on hot and the fan is on the temp stays at about 1/4 on the gauge but if not it goes above the 1/2 mark, this is because when letting coolant go through the heater core it actually acts as another small radiator and reduces the engine temperature, the only other possibility I can think of, since you have already replaced all the other parts is that there may be a possibility of a headgasket leak, most repair shops can test for this.