2015 Nissan Frontier Heat Not Working While Idling


Active Member
  • #1
I'm having a very weird problem with my 2015 Nissan Frontier SV 4x4 pickup truck. When it's idling in my driveway, warming up, the heater only blows out cold air. It doesn't start blowing out hot air until I start driving it. This isn't very helpful to me because when it's cold outside and I'm trying to defrost my window or melt some snow, nothing happens. Nothing melts. I read that the problem could be not enough coolant in the coolant system and that by adding more fluid the problem might go away. I'm inclined to believe this because it seems that when the RPMs are low, the air is cool, but when I begin driving and the RPMs go up, I can feel the heat kick on. I should probably try giving the truck some gas to raise the RPMs while it sits in the driveway. The thing is, I looked in the overflow tank and it looks good. It seems full and everything is at the proper level.

Are there air bubbles in the system? Does it need to somehow be bled? If I simply add more coolant to the overflow tank, will that get sucked into the engine block and displace the air bubbles?

Does anyone know what the problem could be and how I might fix this?


Active Member
  • #2
You most likely have an air gap somewhere in your coolant system. It could be in one of the hoses, in the engine block, or someplace near the water pump. If there's a large bubble, the coolant won't circulate properly. This doesn't just stop heat from blowing into the truck, but it may also cause overheating of your engine so it's important to fix this.

I used to have the same exact problem with my Nissan Xterra, which has the same engine as the Frontier, I think. I would start my SUV and let it idle for about 15 minutes. When I knew the thermostat had opened, I'd rev the engine somewhat. That's when I began feeling the heat come into the truck. The problem was that the air bubble wasn't allowing the coolant fluid to circulate when the pump was spinning slowly, but once the pump spun faster, it pushed the coolant through. So your goal is to get the coolant through your system to get rid of and air that's in there. I'm sure there's a bleed valve someplace, but it's easier to just add more coolant to your overflow tank. It'll eventually get sucked up into the hoses and engine. You're likely just low on coolant.


Well-Known Member
  • #3
Go grab yourself some Nissan coolant. A gallon should be good. Make sure it's the right stuff. All these cars and trucks nowadays require proper coolant. You can't just grab any regular old stuff these days. Mix it if you need to and then add some to the coolant tank. You may need to repeat this a few times until you see that it stops going down or lowering in level. Once that happens, your problem should be gone.

I've heard people say that if you squeeze the top hose after letting your truck warm up for a few minutes, you could push the air bubbles out. Of course you'll need to turn the truck off after warming it up. I'm not sure you need to do this. I think just by adding coolant and then driving it around for a while, that should be enough to push the liquid through. You could always try it though. Here are some good instructions to fix this problem.



Active Member
  • #4
Yeah, it's because of the way the engine and coolant system are set up. In these trucks, the heater core sits higher than the rest of the coolant, so that's why it gets dry if there isn't enough liquid flowing through the system. All it takes is a small gap to stop the flow, so you need to fill that sucker up. Most of the time it only takes a pint or so, so don't go overboard. The reason the water pump can't push the coolant through is because the ports are too large. If they were tighter, then the flow of coolant would be more powerful and would push any air out, but as it stands, the flow isn't too great. At an idle, nothing will happen. The air will remain. Here's where the reservoir is on a Frontier.