i have 2004 explorer no heat but strong ac replaced thermostat and topped off antifreeze…
I put it in the shop for them to fix problem. It came back running worse. Turns out they took out the proair 800 and bypassed it so coolant was circulating but not enough since I was still overheating. I redid everything they did and it runs better. I put in some radiator sealant and that sealed a few things I didn’t want it to. Mainly the overflow which helped keep running just a little longer. I fixed that but it still keeping it running a bit longer.
I noticed when I did the by pass in the back that there isn’t a really marked as to which hose to which so I may have that wrong plus the wiring that I plugged back together there is one I couldn’t find. And two that plugged into fuses back there didn’t say which fuse they went too.
I have since developed a leak in radiator and it overheats. Other than that the van runs great. Way better than before but I can’t afford another radiator or even coolant at this point but before when proair 800 was still bypassed I had heat. When I rerouted the lines in back is when all the cold air just stayed on. Feels like air conditioning is stuck. But I do get warm air right when it starts getting really hot please give me the very best guess possible is it the wire I didn’t plug in. Are the two hoses reversed? Or is it just that I need a new radiator. I live in Alaska and heat is crucial.
Best guess is there is an air pocket in the system. And it will be almost impossible to for the system to work if it has a leak. You need the cooling system to be leak free. Needs to be completely filled with 50/50 mix of coolant/water and bled of no air. Straight coolant or straight water will cause it to overheat even in perfectly functioning cooling systems.
Another thought I had was if both heater hoses are hot, and it is blowing cold it may be that the vacuum hoses didn’t get hook back up right on the back of the control head. If there is a vacuum leak the mode door actuator won’t work correctly.