1998 cadillac deville fans not coming on starts

1- check your fuses 2- if your thermostat needs to be replaced it can cause the fan to stop working because engine never gets hot enough to allow fan to come on. 3- your fan blower motor could be defective and needs to be replaced 4- your fan blower resister may need to be replaced. The fan will still work on high in most cars, but not work at all in others 5- if you have automatic temp control, the control panel may need to be replaced. These are expensive, so get a replacement at junk yard.

CHECK HEAD GASKET.... COULD BE CRACKED BLOCK

Yes when you are sitting in traffic or just sitting the fans come on to cool the engine so if they are not working it will over heat. When you are on the highway the car should not over heat though becouse the wind is cooling the engine at this time.

The fans /fans are turned on by the pcm, using input from the coolant temp sensor, as well as the HVAC system. The cts is on the right rear of the engine below the egr valve.

Sounds like like your radiator fan is not turning on when it should.Check fan relay,fan fuse and check for 12 volts at fan motor at connector.If all checks out then fan motor is most likely bad.

The only other things would be the coolant temp sensor or the engine computer. Alot of the new GM's have the on and off function of the cooling fans controlled by the computer. If the coolant temp sensor is ok, then most likely the problem is in the engine computer.

The normal coolant temp should be around 200-215 degrees.
The cooling fans will come on at around 225-228 degrees.

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.
If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.
The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.

The most common overheating problem with the Northstar engine is a blocked purge line. It's job is to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.The hose goes in to the engine to a crossover and comes out the other side to near the thermostat housing,the blockage may be there.

need to use a voltmeter and tie into the wiring at the fan connectors and see if there is power when the car reaches operating temp, is yes then the fans are bad. also see if either work when the a/c is turned on. they should come on with the a/c. if not still check for power.

The cooling fans will not come on until 225 degrees. Normal temp is around 199-215. Sitting still in traffic most will inch up around 220 or so. When you turn ac on it turns the fans on and may cool down engine, Check fan operation.