I cant get any heat from dashboard only cool air ,could it be my thermostat or heater core

There are several possible reasons why you may be experiencing cool or no heat in your 2002 Jeep Grand Cherokee Laredo after replacing the thermostat and bleeding the air out of the lines. Some possible causes could include:

1. A malfunctioning blend door or actuator: The blend door controls the mix of hot and cold air that is directed through the heating system. If the blend door or actuator is not functioning properly, it may cause a lack of heat.
2. A clogged heater core: The heater core is responsible for transferring heat from the engine to the cabin of the vehicle. If the heater core is clogged, it may not be able to transfer heat effectively, resulting in cool or no heat.
3. A faulty thermostat: If the thermostat was not properly installed or is not functioning correctly, it may cause the heating system to not work properly.
4. A problem with the water pump: The water pump is responsible for circulating coolant through the engine and heating system. If the water pump is not functioning properly, it may cause a lack of heat.

Heater needs Heater Core, Heater control valve, air diverter inside the car and hot water in the heater core. If you just change the thermostat you must have had a reason. If the car was running hot it could be a radiator clog. If the core is clogged no heat. If the heater core was drained when you changed the Tstat there may be air in it - if so no heat. If the control valve (on the heater hose) does not shift- no heat. If the diverter door in under the dash does not direct the fan air through the heater core- no heat.

Is your air locked slacken off top hose and make sure your getting a good flow of water no air

Is the problem the thermostat, or is the heater control blend door not diverting the blower air across the heater core....or is the heater core clogged? The thermostat is actually the least likely cause of cool air in the passenger compartment.

Thermostat.? if you haven't? Do it first then try it. While the car is running for a while touch the heater hoses that lead to the firewall. if one is cold and one is hot? You have a blocked Heater core. Follow the hoses back to the engine. Unconnect them both. By using a garden hose flush out the heater core do one side and then reverse by doing the other hose Lots of junk will come out so be care ful. Mistake people make is "Flushing the system" That doesn't mean your flushing the heater core.
Seeing that you have done everything else it could be the thermostat which you didn't list or the heater core being clogged. When you finished installing the thermostat and flushing the heater core out. Replenish the coolant system . If you have a bleeder on the thermostat housing? use it . loosen it and top off the fluid until you see fluid comeout of the bleeder. The system being air bound would cause no heat..

your air damper or diverter may not be working.this is basically a mechanism that opens a flap by your heater core to control the amount of hot air that comes out.There is a rod that this flapper pivots on and if this rod is broken or the motor that operates it is not working you will either have heat all the time or no heat at all depending on which position it broke at.I know because my torrent has the same problem.To fix my problem they have to remove the dashboard to access the heater core which amounts to major $$$. I hope your problem is an easier fix. good luck

Sounds like a thermostat or cooling system issue. Change the fluid and the thermostat. It will do your engine good so it's money well spent.

Water-cooled engines supply heat for the passenger compartment by circulating hot coolant through a radiator-like heater core. The passenger compartment fan forces air through this heater core and into the passenger area. The flow of coolant for this purpose can be controlled with a valve in the line that is adjusted when the heat control is moved or via a flap that blocks or opens the air path through the heater core to adjust temperature.
The effect you describe can be caused by several different sources:
- A slipping belt which turns the water pump. - A partially collapsed hose in the circuit for the heater, causing a reduction of water flow to the heater core. - A heater core internally blocked from deposits from the water component of the coolant. - A valve which is not being adjusted through its normal range by the dashboard control. - A flap suffering the same limitation as above.
Another effect our personal vehicles generally show with age is caused by abnormally low engine friction attributable to a particular additive we use that reduces engine friction so much that the thermostat that controls coolant/engine temperature is wide open but the engine doesn't heat enough to bring the coolant temperature into the normal operating range. We notice on two of three vehicles, that rolling on a long downgrade (engine not loaded) will cause the engine temperature to drop below its customary operating temperature.
If you have a dashboard temperature gauge, watch it to see if it rises into the middle of the range or not. If not, there may not be much you can do other than flush the cooling system, making sure that the heater control is set to its highest temperature to ensure that the heater core is in the loop while flushing.

No, you just won't have water flow through the heater core, Coolant flows through the engine through the lower radiator hose as the water pump sucks it out of the radiator and pushes it through the engine. It then flows out the top radiator hose when the thermostat opens. It then flows into the radiator to cool off.

Is your heater core leaking?

the selector flap is not moving all the way to cold or hot position. Under the dashboard on the passenger side is a heat/ac box where all the duct work for the vents originates from. inside that box is the radiator for the heater and the cooling coil for the ac. the selector flap between them is stuck or not moving all the way.