I have a 2003 x type jag and the fan stays on after turning car off. I just found out the heat doesn't work so wondering if I change the thermostat would that help, I also think I'm leaking antifreeze but can't find the leak.

 

Burton: Your Jag most likely:
+ Has a slow coolant leak, probably a stress crack in the coolant reservoir or a leaky seal in the water pump
+ The fans stay on because the coolant level is low,
+ The heater blows only cold air into the passenger compartment because the coolant level is low, and
+ Changing the thermostat won't help because it's not the problem

To confirm it's just a coolant leak, try this:
1) When the engine is cool, remove the cap to the coolant reservoir, above the driver-side front tire
2) Fill the reservoir with water
3) With the reservoir cap still off, warm the engine to normal operating temperature
4) Expect the water level in the reservoir to drop as air "burps" from the system. When this occurs, keep topping it off with water
5) Set the temperature controls to "Hi" and confirm that hot air again blows into the passenger compartment
6) Turn off the engine.
7) Did the fans turn off when you shut off the engine? If 'yes', the fans are working properly, and the reason they sometime do not turn off is because the coolant level is low, due to the leak.

Until you fix the leak, keep a jug of water in the car and a watchful eye on the coolant level. Don't run the engine with low coolant, or you risk a blown head gasket and major repair headaches.

Look to see if the leak is from the coolant reservoir or water pump. Stand by the driver-side front tire and look down between the battery and coolant reservoir. Do you see any dark stains on the top of the transmission housing, either orange-brown or pinkish (depends on the color of coolant you're using)?

If stains are under the coolant reservoir & brake master cylinder, it's probably from a reservoir leak. A leaking water pump will stain under the pump - the pulley & skinny belt on the engine next to the battery.

If you suspect the coolant reservoir, check two areas prone to stress cracks:
+ The two nipples where hoses connected to the top of the reservoir, near the firewall
+ The flat bottom of the reservoir
Use a dry paper towel to touch under these spots and check for dampness on the towel. If you don't find any dampness with the engine cool, try again CAREFULLY after the coolant system is hot and pressurized.

Here are a few threads with pictures of reservoirs that have stress cracks in these locations:

https://www.jaguarforums.com/forum/x...oolant-115783/

https://www.jaguarforums.com/forum/x...ervoir-126434/

https://www.jaguarforums.com/forum/x...re-cap-125477/

After you find and fix the leak, remember to drain some water and add anti-freeze before winter hits DC. To drain water from the radiator, lie on the ground by the front bumper with your head near the passenger-side headlight. Under and behind the bumper, look for a ~2 inch square hole in the black plastic cowling. Up inside the hole is a drain plug for the radiator which has a slot to loosen it with a flat blade screwdriver.

Keep us posted on what you find. If you don't locate a leak in the coolant reservoir or water pump seal, the next suspect is a possible crack in the rigid plastic coolant line above the thermostat housing.