No heat

My 2008 avenger is not getting serculaiton through heater core unless rpm are above 2000 thus while ideling there is no heat just blows cold air. cheked heater core for blockage there are no blockage, water pump maybe car has 50000 miles ?. to replace water pump my mechanic said it is a 8 hour job kinda spendy for a car with low miles whant to make shure this is the problem

If the engine isn’t overheating, then I don’t think there is a water pump problem. Check to see that the coolant is up to the proper level in the radiator. If it isn’t, this might be the problem. The next issue might be air in the system. Sometimes you can purge the system by waiting until the car is cool, remove the radiator cap, set the heater on full heat, then start the engine and let it reach full operating temperature. This may purge the air from the system and bring back the heat.

Do you have enough coolant?

Besides the good comments above, has the cooling system be properly bled of all the air? If not, it might be worth trying. & how do the two heater hoses that go through the firewall feel to the touch when engine is warmed up and idling, you have the heat control on full max, blower on max, and aren’t getting the amount of heat you think you should? One more thing, if dash temp gauge is showing a lower than normal reading when engine is warmed up and idling, that could indicate the thermostat is stuck slightly open.

I have changed thermastat bled system of al air and is full of coolant heater hoses are cold to touch untill motor rpms are raised to above 2000 rpms as soon as it you let Fidel they cool off. Have driving car for some time through the summer months and it doesn’t over heat puzzeled?

This sounds to me like you still have a thermostat problem. That’s the gadget that is supposed to save some hot water and send it to the heater. Suggest to take it out, and take it down to the parts store and verify it is the correct one for your car. Compare it to the one they bring out from the parts stores for the car. Some cars use a double acting thermostat, where when it opens one passage, it closes another, I think that type is called a “bypass” thermostat, some use a single acting version where it just opens one passage when activated by heat. You may have the wrong type installed.

Also, the thermostat could be installed incorrectly. Backwards is a always possible, probably has been done thousands of times by diy’ers, but the more common mistake is that the air bleed hole isn’t positioned correctly. Be sure to follow the instructions on how to position the thermostat’s air bleed hole.

Also, it could be the correct part number, but it isn’t working. I always put a new thermostat in a pot of water, put a thermometer in the pot, and slowly heat the water up. See if it opens at the correct temperature, and the number of mm it is supposed to open. Your factory service manual should have that info.

An air bubble can cause this also. I’ve never seen any forums on air bleeding avengers, but some cars are a lot easier to do this than others. An air bubble can lodge in the cooling system and block the coolant from flowing, and it will tend to block narrow passages like heater hoses. One thing your mechanic could do is remove the heater hoses and test to see if coolant is flowing through them without impediment.

The next possibility would be that the water pump simply isn’t pumping at the volume rate it should be. The impeller could be damaged for example. The way I test for this on my Corolla is to remove the top radiator hose and see how fast the coolant pours out once the thermostat opens. It should really pour out of that hose, not just trickle out. You could ask your mechanic to test for that. This has to be done carefully so as to not run out of coolant in the process of doing the test of course.

Thank you for your suggestions I had my mechanic install thermastst hope it was the correct one and checked before and installed correctly. Recently they installed a electric water pump now I have heat don’t think it is quite the same as before but it is working doesn’t seem as warm might have them try another thermastat