What relay 1999 taurus makes cooling fans come on correctly?not radiator not CTS rplaced that not head that repaired coolant bottle reolaced water pump ok overheats and fans want come on unless unplug CST

There should be both. Should have a temperature switch, an A/C switch, a defrost switch that all send signals to the ECU. And there is a fuse and relays in the circuit for the low and high speed fan controls.

How To Solve An Engine Overheat Condition - EricTheCarGuy
https://www.youtube.com/watch?v=hUzOTnsWImI

Engine overheating. How to fix a overheating car engine on your car
https://www.youtube.com/watch?v=evpaTW2WJ5Y

Hi Lucas, Im AL the owner of Big As Auto Repair

Lucas, first thing to check for is make sure the cooling fans are coming on. Second thing to check and very common issue after replacing the water pump, is air trapped in the system. Make sure you get all the air out of the system. Some systems have an air bleed screw to help with this issue. If the fans are coming on and all the air is out of the system, then you'll want to check for coolant flow in the radiator. CAUSION: Let the engine cool before taking the cap off the radiator. After removing the radiator cap start the engine and let it idle, if the coolant does not flow after reaching operating temp, then you may have a restriction somewhere in the system. The other thing to check is make sure you put the thermostat in correctly, some vehicles you can install it backward, make sure the spring end is going toward the engine. If you have coolant flow and the coolant is blowing out of the radiator you may have a blown head gasket or timing issue. Hope this helps and please send people to my auto-repair-website at: http://www.bigasautorepair.com/

The most common overlook thing is you got a air pocket, so before you go spend your money turn Heather on full blast, open the radiator cap, car running look for air bubbles, takes patience cause you got to wait for the thermostat to open up, you must refill the coolant really really slow snail pace, some car have a bleeding valve others have two chamber on the overflow bottle,good luck, if that doesn't work change the thermostat first and if that doesn't work I'm afraid you may need to replace water pump. . water pump

Have system pressure checked first, your looking for leaks , a bad head ,a defective water pump. Next make sure cooling fan is operating and operating correctly. Items that affect cooling fan are coolant temperture sensor and relay and the circuit and fan itself. If area by thermostat is bottle necked chances are you have a defective thermostat .

replace your radiator cap.

bad low coolant switch or still low on coolant.

Engine Cooling The cooling system components are the:

• engine coolant temperature sensor (ECT sensor) (12A648)
• radiator (8005)
• degas bottle (8A080)
• radiator draincock (8115)
• water pump (8501)
• water temperature indicator sender unit (10884)
• water thermostat (8575)
• dual speed fan motor assembly

The water pump circulates the coolant.
The water thermostat:

• controls the engine coolant temperature.
• allows quicker engine warm-up.

The degas bottle:

• provides a location for fill.
• contains coolant expansion and system pressurization.
• provides air separation during operation.
• replenishes the engine coolant to the system.

The fan motor (8C607):

• operates only when the ignition switch is in the RUN position.
• will not operate with the switch in the OFF position.

The engine coolant flows:

• from the lower radiator hose (8286) to the water pump.
• from the water pump to the engine block and the cylinder heads.

A closed water thermostat returns the engine coolant to the water pump; an open water thermostat allows the engine coolant to flow to the radiator.
Engine coolant provides freeze protection, boil protection, cooling efficiency and corrosion protection to the engine and cooling components. In order to obtain these protections, the engine coolant must be maintained at the correct concentration and fluid level in the degas bottle.
When adding engine coolant, use a 50/50 mixture of clean, drinkable water and engine coolant.
To maintain the integrity of the coolant and the cooling system:

have u bled the cooling system ?warm the car and cut the car off right before the fans come on ,let sit for 30-35 minutes,see if the coolant drops in res. if so repeat process untill coolant stops droping ,then drive car regularly if overheating stops ,but monitor it because it will drop somemore/there has been reports of new and rebuilt water pumps nt having correct propelar mounted on them/ backwards etc. if this helps let me know [email protected]

My friend had a 1999 taurus and had the same problem, his coolant would leak from around the overflow bottle because the system was backing up. His problem was a partially plugged radiator. I know this probably isnt the news you wanted to hear, but I'm pretty sure thats going to be your problem. sounds like you've replaced everthing else short of the radiator and water pump. Good thing is i remember him saying it was reasonalbly priced, so good luck.

you probably have air trapped in the system. Have dealer or radiator shop bleed system.

I assume your cooling fan is working.

what engine v6 or v8?

SECTION 303-03: Engine Cooling 2001 Lincoln LS Workshop Manual
DESCRIPTION AND OPERATION Engine Cooling The cooling system components include the:

• block heater (optional)
• cylinder head temperature sensor
• fan blade, fan motor and fan shroud assembly
• radiator
• pressure relief cap
• degas bottle
• radiator draincock
• water pump
• oil cooler (optional)
• water thermostat

The water thermostat:

• controls the engine coolant temperature.
• allows quicker engine warm-up.

The degas bottle:

• provides a location for system fill.
• contains coolant expansion and system pressurization.
• provides air separation during operation.
• replenishes the engine coolant to the system.

The fan blade draws air through the radiator to help cool the engine coolant.
The fan motor:

• operates only when the engine is running.
• will not operate when the engine is off.

The engine coolant flows:

• from the lower radiator hose to the water pump.
• from the water pump to the engine block and the cylinder heads.

A closed water thermostat returns the engine coolant to the water pump. An open water thermostat allows the engine coolant to flow to the radiator.
Unsatisfactory coolant materials:

• Alcohol-type antifreeze does not provide adequate water pump lubrication.
  • has lower boiling point
  • reduced antifreeze protection
• Alkaline brine solutions will cause serious engine cooling system damage.

The cylinder head temperature sensor provides a signal to the temperature gauge.

• will invoke failsafe cooling.

The optional block heater:

• electrical heating element is installed in the block cooling jacket.
  • uses a standard 110V (220V in Europe) electrical supply
• keeps the engine coolant warm during cold weather.

The auxiliary water pump (3.9L only):

• provides heater coolant flow boost.
• has a secondary function of providing engine-off cooling.