Hi all - our daughter purchased a 2007 Nitro RT 3 months ago. Now that the weather is turning colder, she says that the heater is not working properly. The fan blows and when the engine gets up to speed or if it's hot outside, it will blow hot. But only if the car is in motion and it only gets hot on defrost. She lives 30 minutes away and is visiting tomorrow, but Is there a fuse I should be looking for? If si, is there a diagram I can download somewhere? I don't have many answers until I see the Nitro tomorrow.
Thanks for any and all suggestions!

 

the symptom you described -heat only when moving- can be a low coolant problem. when the engine is turning the waterpump faster...more cooler flows thru the heater core and you get heat...at idle less flow and add in low coolant level...low heat output.

so check the coolant level first. if the vehicle uses a non pressurized coolant reservoir...when its cool, check the level in the rad and reservoir. if it uses a surge tank reservoir you only have to look at the surge tank level. If the coolant is low...its probably has a coolant leak. fill it with the correct coolant and pressure test it with a cooling system pressure tester.

use the correct coolant. I would buy it from the dealer bc I don't like using works for all coolant.

the symptom heat only on defrost is more likely to be a mode door function...does the mode door move to each setting...defrost, vent floor?

 

Hey primem - thanks for the reply. I will mention to her to check the coolant tomorrow.
The heat only on defrost thing - She says she hears a definite change when she switches from AC to heat but I'll have to ask if it blows to the feet, to the front, etc.
My 2000 Dakota defaults to the defrost when the heat/AC selector does not function properly. It must be a Dodge thing to default to defrost?
Thanks, again!
I'll let the forum know what's up on Sunday.

 

My daughter checked her coolant and it indeed took almost a gallon of pre-mix. She drove Saturday and Sunday with the heat on high and the blower on full. There was a somewhat increase in heat to the defrost and face but the blower to the feet is still cool. Does she just need to run it longer with it on high heat? I'm not that familiar with that vehicle. My truck it helped to drive up a hill to move some of the air out of the radiator hoses. I would think the Nitro would be more advanced than that. Thermostat maybe?
Any ideas, please and thank you!

 

hard to say over the internet.
if the coolant wasn't coming up to temp soon enough a p0128 dtc will set.
new cars required vacuum filling to get all the air out...surge tanks systems are better - not sure what you have- but it may take a while of thermocycling to get all the air out after pouring it in by hand.