No heat in 99 ford taurus

I had the same problem with my 99 ford taurus. My ford taurus did exactly did same things that your vehicle is doing. runs cool on the freeway because the air is going through the radiator and cooling the water down.I checked the cooling fans, radiator and hoses for leaks also replaced my thermostat. nothing solved the problem. turns out that the new antifreeze does not come with a lubercant property any longer. you have to buy the lubercant additive separately and then add it to your cooling system when you replace the antifreeze. the lubercant protects your freeze plugs, water pump, radiator, thermastat from rusting out. Meanwhile because of the absents of the lubercant, my water pump impellers rusted out and dissolved. so the water pump had no fins to circulate the water. Luckly for me, I discovered that my car was still under warranty due to an extended warranty I had purchased when I bought the car. ford dealership replaced the water pump. Problem Solved.

First The heading says 99 Taurus but the question says 99 f-150. Second, are you saying that the engine is overheating? The heater won't work if the level of coolant is low and that would explain overheating. The thermostat controls the temp of the heat, so if it is stuck closed then water can't circulate to the heater and the vehicle would overheat, but this is unlikely.

the other answers seem to concentrate on a non-working heater. Good luck with this problem.

possibly the bled door is stuck open so only the cold air from a/c works when on defrost vs closing to allow heat to cycle through the system as defrost runs through the a/c system

hi there it sounds like the matrix has gone it is at the back of the centre panel at the bottom when the engine is hot touch the matrix to see if its warm

The blend door may be hanging up .

start with the bascis, need good coolant in the system, if you have been adding a lot of water then you need to drain and fill with fresh coolant, you have allready replaced the thermostat, make sure you have no coolant leaks, would be easy to notice due to coolant on the ground or tracing, do you have good air flow throught your radiator assy, if the front grille area is clogged with dirt/bugs/debrie then it has no way to transfer heat from the coolant, need to check and clean it out, next would be to check and or repace your water pump, the fins on the back side of the pully which you cannot see untill you pull of the water pump could have rusted away which means no flow.

ck water pump? did u ck water pump and fan working?

sounds like you have a internal blockage problem, trying blowing some air through the heater core, see if you get any rust/debrie out, check the hoses to and from the core for blockage, these engine have issues with the water pump fins rust off, i have heard of cases where the fins rusted off but the car never would overheat but it never blew warm air from the vents.

Sounds like a stuck thermostat no heat water not circulating to heater core engine overheats stuck thermostat won't let water circulate through engine

Just finished fixing my daughters 1999 taurus heat. It would blow warm only when running down the road. At idle it blew cold. I started with replacing thermostat, and water pump because they are the easier fix. Still did not help. Then I replaced the heater core. A daunting job but not that hard to move the dash slighly out of the way to replace. There is a good write up at tarusclub.com. After that, heat was better but at idle, it would still blow cool sometimes. Researched and found answer. Park car on the steepest hill you can find with front of car up. Start car and take off reservoir cap. Let car warm up and keep rpms about 1500. After a while the fluid will come running out of the car and all over the place but it will bring air bubbles with it. Reduce rpm, add more fluid and repeat about 3 times. It will make a mess but after that, the heater works perfectly. We get heat long before the temp gage indicates any and it never blows cold unless you lower the temp.