Heater I own a '03 Intrepid, and it won't produce heat unless I have the rpm's over 1500. It produces heat going up hills or at a steady pace on the highway, but going down hills or slowing down it blows out very cold air. Don't know what is wrong or how to fix it.

take it to a radiator specialist shop as it indicates that there is an air lock in the cooling system that needs to be removed so that full coolant flow can be achieved

could be low on antifreeze. at a higher rpm it will produce heat. but at an idle it cannot circulate the antifreeze properly. check it and fill to proper level. hope this corrects your problem.

Have you checked the PCV system?? If its stuck in the closed position then you will lack power and turbo boost. A vehicle needs 3 things to make it run proper; FUEL,FIRE and AIR. Try that and see if it helps.

Oh no! What do you do when your car heater not working? How do you figure out why there's no heat in car? What if you have no heater in car? Before you start trying to figure out how to fix car heater yourself, you should know a little about how your car's heating system operates. That will help you to figure out your car heater problem and why your heater isn't working properly or even at all! So, let's talk about how your heating system functions and then about some of the more obvious reasons that it you may be getting no heat from car heater. In order to heat up the inside of your car, the heating system uses some of the excess heat produced from your engine. Actually the engine produces so much heat that if you didn't have a way to release it (the heating/cooling system in your car) it could harm and even destroy the engine! That is why the heating/cooling system is set up to remove some of the heat and keep your car running smoothly.

If your car has hydraulic tappets and low low oil pressure at engine speeds then it can make tapping noises. Oil pressure is needed to maintaine the tappets clearances, excessive cleaeances will produce noises.

If it won't produce heat then you have an issue with your heater core. The heater core could be bypassed, in which case no hot coolant will get to it to produce heat inside the cabin. The heater core could be stopped up with dirt/debris, in which case the heater core can't radiate heat to produce heat in the cabin. The ducting in the dash could not be allowing the hot air to flow to the vents - therefore no heat in the cabin. I'd start with the heater core and check to see if it is bypassed. This generally happens on older vehicles because the parts can be harder to find.

It may be that the light is being tripped due to an "over voltage" condition. The faster you spin the alternator/engine the higher the voltage output of the alternator. I would test the voltage coming out of the alternator. It should be at about 14.3v or so max. If it gets into the 16v+ range when you increase the engine RPM then the voltage regulator has failed and needs to be replaced.

http://realfixesrealfast.com/realfixesrealfast.com/Heat_%26_Air/Pages/Chevy_PU_A_C_blow_hot.html

This may be your problem. The blend door may not be opening.

reverse the heater hoses and drive it for a cpouple of days your heater core is plugged and by reverseing them you can back flush the heater core after 2-3 days reverse them again

Have your egr valvle checked, if not operating properly it can cause engine 'pinging' which sounds like what u are describing. Let me know how it goes. countrycurt0