Radiator fans don't ever turn on, engine overheats unless heater is on?

Question

I have 1999 Jetta 2.0 that seems to be having cooling issues. At freeway speeds the temp gauge will climb consistently unless I have the heater blowing at max. The heater blows hot/ very hot air when on and this bring the temp back down to the normal 190 degrees. The upper radiator hose is hot when checked, and the lower is hot towards the engine/ thermostat but cold near the radiator. Does this indicate a blocked radiator? The radiator fans will not turn on even when the engine is nearing 260.

Answer 1

There are different temp sensors for the gauge and fans. sp the one that controls the fans may have gone bad. Is there only one fan? If so, start the car and turn the a/c on full blast. This should force the fan to run regardless of whether or not the temp sensor works. If there are two fans, this test is invalid. If the fan runs with the a/c on, then the temp sensor for the fans is your prime suspect. I have changed a bunch of bad temp sensors on these VW 2.0 motors, they go bad pretty often. Most new ones from parts stores are an "updated design" that VW released several years ago in an attempt to cut down on the problem.



I should also note that if your a/c doesn't work, the test mentioned also can not be trusted.

Answer 2

The heater matrix is a part of the cooling approach so if it is blocked the coolant will not flow into as a consequence providing no cooling whatever irrespective of in case your radiator fan is on all the time or not. The radiator water will be cool however it'll just take a seat within the radiator if there's a blockage. You could take out the matrix your self, must be particularly simple. I did it on an old Orion I had and i have never a first-class deal of mechanical knowhow. Just get the Haynes guide and provides it a go. As soon as the matrix is off the vehicle you can blow by means of it to look if you can put off the blockage (that is what I did). If that does not work you may desire a new/replacement one. Cannot see why the eu would burn out although. If the fan was once on constantly (which it probably could be i will best see that it will injury the motor of the fan at worst. EDIT : If the heater is blowing cold then there is certainly a blockage. Occupied with it, it could now not even be within the matrix. You can ought to follow the cooling method feeling the pipes and looking for an obvious exchange in temperature. To be able to show the place the block is

Answer 3

could be

1. bad Temperature sending unit and/or temperature sensor,

2. bad radiator fans or relay

3.dirty radiator

4. bad thermostat

if you run your car on the freeway your car should not heat up, due to the fact that there is air being force thur the radiator, at a high speed, it should be working like your heater core.

after you run your car put your hand all over the radiator, but be careful not to get burned. if you find any cold spots on the radiator, that is the area that is plugged up and antifreeze is not circulating,so your care overheats

5. maybe bad water pump

Answer 4

Need to check fuses first, then check if the fan really works, then the sensor for the fan. messing with vehicles 49 yrs