Why is my heater not working?

The heater hose connector to the heater core broke, I fixed that problem, replace the coolant, truck has no heat. When idling, the temperature gauge stays in the middle, when I go to drive it, the gauge goes way up and no heat.

My heater is fading hot and cold air when turned on. Sometimes the heater will hear up for 10-15 minutes and cold and sometimes it doesn't heat up at all. Do my heater needs to be replaced? If so, what is the estimated cost to replace? Thank you for your time.

LD

I have the same issue on a 2005 SE 4X4 with 80K. I don't see any replies here, have you gotten the problem diagnosed yet?

No, nothing yet. Still searching. As much as I don't want to, I might have to take it to the dealer. It's getting colder and colder :(

I too have a heat problem--heat works fine when engine is revved. Not sure its a water pump issue of vacuum issue. Also have had rear diff replaced.

Mine is doing the same thing. Runs real warm when revved up or accelerating, but cools right off when idle or coasting.

Our pathrinder is going the same thing, driving the heat works, but slow down and the heat runs cold.

Our 2006 is doing the same thing, heat only works when the vehicle is moving or reveved up. Wish someone had an answer.

Called to take my suv in and described the problem, and they said that it sounded like the heater core needed back flushed. If it works, will let you know.

I have an appointment on the 18th for mine. They told me to check the antifreeze level, I did and it was fine. They claimed that it could have a air pocket just before the thermostat. I think this is some kind of Nissian design problem, we should check deeper into it. I will post my results from the dealer.

Place that I took our SUV to, said that Nissan vehicle were well known to get sludge build up in the anti-freeze and that the heater core would need to be flushed. But ours had a leak in the back heater part. He said that a piece of steel runs from the back of the vehicle for the heater all the way to the front. When nissan built it they put this part on and then put on the body. So the only way to get to they whole thing was to lift the body off. Which is expensive. I just had them cut off what was bad and replace just that section. So my anti-freeze was taken all out then replaced. The hardest job they had was getting the air bubbles out.

So did this solve your problem with the heater not being hot unless the vehicle is revved up?

Yes, it did work. Haven't had a problem yet. So it may have been both things that were done that made it work. Emptying the anit-freeze got the sludge out. And fixing the holes in the line for the back heater.

Ok my dealer did a pressure check on my coolant system. He said I have a manute leak on my heater core where the tubes hook to the core at the firewall. He said that it is letting air into the system which is causing the problem with the heat. Cost to repair $500.00.

Ok I took mine to another dealer, becuase I thought the first Dealers quote was too high ($500.00).

They replaced all of the plumbing at the firewall where the heater core is. That fixed the leak and my heating problems. Total cost. $315.00

My car heater will only work when I push the gas. It will not work when idling. Help!

I noticed that the heater was blowing cool air. I raised the temp on the dash to 85 degrees and still no heat. Heater core or thermostat and how do I tell which it is? I am not mechanically inclined but I can follow directions. Is there a way to rule out whether it is a heater core or a thermostat problem?