1990 LeBaron 3.0 engine. Radiator cooling fan replaced not turning on to cool engine, thermostat and sensor was replaced also. Worked for awhile, now not working. Any suggestions? Wiring? Water Pump is okay. How many relays or sensors is there to turn on the radiator cooling fan?

The LeBaron uses the Coolant temperature sensor data for both the engine control and the radiator fan control. The PCM sends a closure signal to the Radiator Fan Relay when it wants the cooling fan to run. There is no separate switch for the fan itself.

The Coolant Temperature Sensor is located: Under hood, driver side, upper engine area, front of distributor, mounted in intake manifold

Are you sure the head gaskets needed to be replaced was it to stop the leak? Go to an auto parts store leave a deposit and use the tool for free. One tool has a cap that fits on the cooling system and has a pump on top You pump the system up to 15 pounds and look around the engine and the radiator for leaks. This is what your repair shop should have done before they replaced head gaskets. Putt a meat thermometer in the radiator when it is cold start engine. Let run. Put hand on upper radiator hose when the thermostat is starting to open the hose will turn hot right away the thermometer will read 180 to 195 If the engine starts to over heat the thermostat is bad but if it opens the temp will slowly rise to 200 to 215 that will be fully open and around here the fan will turn on and cool the engine down( make sure the air is off or one fan will be on all the time) if fan comes on late replace temp sensor for radiator. If everything works the radiator is probably plugged

Thermostats in cars are often neglected, if not totally forgotten, units. Yet they play an important role in the general performance of cars by restricting water flow until the engine has warmed-up. Thermostats are heat sensitive valves that open and close. On cars they prevent circulation of coolant to the radiator until the engine is warm enough. When the thermostat is closed water only flows through the water pump and water jacket to let the engine warm quickly. When the thermostat opens, water can then pass through the radiator for general cooling.
google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad); Having a car that warms quickly is particularly useful in cold weather when you want to use your car heater as soon as possible. The thermostat is in a small housing positioned where the top radiator hose connects to the engine. The best time to check or change a thermostat is when you are servicing your radiator because you need to drain the cooling system
first. Hence, a thermostat change is a good time to flush and clean your cooling system, check all radiator hoses and the radiator pressure cap. Be sure you have the correct cap on your radiator and it is not rusted. Thermostats are small, inexpensive items. You can test them by heating in water and checking their operating temperature with a thermometer. However it really is quicker and ultimately more reliable to simply fit a new one,
1. thermostat common problems (replace every 50-60k miles)
2. thermostat switch sensor (which turn your cooling fan on and off)
3. check and see if the cooling fans is running when the engine get to its operation temperature. (fan motor can be fault)

there is a switch in the engine intake or cylinder head that controls the cooling fans. The switch is the one with only 1 green wire hooked to it. Turn the key to run, with the engine stopped pull this wire off and touch it to a ground( cylinder head, engine block) and the fan should start, if not look at the fuse, if it does you need to replace the switch.

A lot of different things fall into this senario.Low coolant level,air in the cooling system,and a stuck thermostat,or,a bad coolant sensor,or even a bad cooling fan relay,or the cooling fans are bad.Turn the defrost on or the ac,the cooling fans should come on if the fans,and the relay are ok,if so,replace the thermostat,and coolant sensor,and bleed the cooling system of air.

my 1990 325i bmw is running hot
it seems to have a lot of air in the cooling system
i replaced the head gasket, water pump and thermostat
how do i get the air out of the system

MAKE SURE WATER PUMP WEEP HOLE NOT LEAKING.IF SO REPLACE IT.MAKE SURE YOU HAVE 50/50 MIXTURE OF ANTIFREEZE AND WATER.MAKE SURE YOUR COOLING FAN IS WORKING .IF YOU GOT A CLUTCH FAN IT SHOULD NOT BE LOOSE OR FREE WHEELING.IT SHOULD HAVE RESISTANCE WHEN YOU TURN IT BY HAND.IF YOU GOT ELECTRIC COOLING FANS TURN ON AC SWITCH TO SEE IF THEY COME ON IF YES FANS WORKING IF NOT COOLING FANS RELAY IS BAD.ALSO SCAN IT TO CHECK COOLANT TEMPERATURE SENSOR.TOO SEE IF MATCHING THE ENGINE COOLANT TEMP IF NOT REPLACE IT.IT WILL CAUSE YOUR COOLING FANS NOT TO COME ON AT A SET TEMPERATURE.CAUSING ENGINE TO OVER HEAT.. .

Volvo Radiator, Thermostat and Sensors Your cooling system's temperature controls include all coolant temperature sensors, Volvo thermostat, Volvo radiator or expansion tank cap, cooling fan(s) and fan clutch (if equipped). These cooling system parts function primarily independent of the engine but control the engine either through cooling or by sending control signals to your Volvo's electronic systems.
The Volvo thermostat is a spring-loaded valve that opens and closes based on the temperature of the coolant flowing through it. A high temperature reading followed by a drop to normal temperature (or a continuously low temperature) is a common first sign of a sticking Volvo thermostat. However, many other conditions may cause these symptoms, so you need to know how to eliminate each possibility.
The Volvo radiator or expansion tank cap is also a spring-loaded valve reacting to system pressure. It serves to maintain proper system coolant level at predetermined pressures. It must always be replaced with an exact replacement cap with the same pressure setting. Never use other caps except for short-term emergencies!
A belt-driven fan blade for pulling air through the Volvo radiator is usually on the Volvo water pump pulley and should have a fan clutch to control it. The fan clutch allows the fan to turn with the belt at low engine speed and "free-wheel" at higher speeds. A bad fan clutch either doesn't allow the fan to spin at low speed (overheating in traffic) or doesn't allow it to free-wheel at high speed (potential overheating on highway or reduced gas mileage).
An electric fan can be either by itself (usually front-wheel drive) or auxiliary (used with a mechanical fan). Both types are controlled via a temperature sensor - in the Volvo radiator or upper Volvo radiator hose or on the Volvo thermostat or Volvo water pump housing. This sensor is usually an on/off type switch with a fixed temperature setting. (Some vehicles may have 2-3 settings for multi-speed fans.) This sensor is commonly called an "auxilliary fan switch".
Other common temperature sensors are: 1) gauge sender (variable output); 2) warning light sender (on/off type); 3) lambda and/or fuel injection sensor(s) (variable to control fuel injection settings); 4) thermo-time switch (cold start valve control). Your Volvo may have other sensors as well.
Temperature control is critical to both performance and emission control. Unfortunately, this system is the most difficult to troubleshoot without proper equipment and diagrams. It's even more difficult with computers that adjust timing, idle speed, vacuum and fuel delivery automatically to make up for potentially faulty temperature sensor signals.
Maintenance of your cooling system sensors is virtually impossible since there's nothing really to "maintain". Keeping them clean both internally (coolant replacement) and externally (engine cleaning) is the best way to ensure trouble-free driving. Checking and replacing all parts at the factory-recommended time or mileage limits helps as well

Your temp gauge reads low on the highway, and one-half in the city?
You need to replace the thermostat. It is sticking open.
Driving at highway speeds, the blast of air that the car is cutting through enters the radiator, thusly cooling it, and the coolant inside the radiator... In town, with the lesser amount of air being forced into the radiator, (slower speeds), the coolant temperature rises. Replace the thermostat, and you will be OK.