[vedder012]

This just started happening after the dealer fixed an oil leak and replaced the left head and gasket back in early November...recently been needing to use the heat with the colder weather and noticed when I'm not moving..(idling or in park) my heat blows cold air..even when the truck is warmed up...

Once I hit the gas and start moving the heat blows nice and hot.

so anytime my heater is blowing hot air and I stop at a red light or stop sign it quits and cold air blows...

I'm not really sure what to check. I haven't had time to stop at the dealer and have them check it out but any help would be appreciated.
Thanks

 

[Zero Six LE]

Air in your cooling system. It was not bled properly when they did the engine work. Fill your recovery tank before driving your truck next time. After you park it overnight, check to see if the level dropped. Keep filling the tank (cold engine) until the level no longer drops. At that point just fill to the appropriate level using the marks on the tank.

 

[k_mcbride]

Air in your cooling system. It was not bled properly when they did the engine work. Fill your recovery tank before driving your truck next time. After you park it overnight, check to see if the level dropped. Keep filling the tank (cold engine) until the level no longer drops. At that point just fill to the appropriate level using the marks on the tank.

x2.....this same exact thing just happened to me!!! I would definately try the cooling system trick before anything else. Seemed to work awesome for me. I had to add fluid to the recovery tank twice, but its at the right level now and blows hot air when idling. The level in the tank will look correct at first sight, but if it has bubbles in the system they will make it apper that way.

 

[vedder012]

alright cool guys, thanks for the help, ill try this tomorrow.

 

[colin123]

nissans tend to collect air bubbles in the cooling system fairly easy and they like to get stuck in the heater core. this tends to happen over time too even without having service work like that done. just do as stated above or since it happend since work you had done the dealership has a special filling tool that they could use to try and get the rest of the air to purge out with. i'm sure they wouldnt have a problem doing it since the air got in during work they did and they never got it all out

 

[TheRealDoug]

could also be that since it is idling, the water pump is not pushing as much hot water through the heater core as it does when you are moving.

 

[Zero Six LE]

could also be that since it is idling, the water pump is not pushing as much hot water through the heater core as it does when you are moving.

That should not matter. When the cooling system has no air in it, the air would still be hot even at idle.

 

[CT_Nismo]

I think you have an obstruction in the line that feeds the heater core. This effectively blocks the core when the water pump is at low output (idle).

The hypothesis that air the core is the issue is at odds with itself. Trapped air can be in the core, but it blows out with increased water pump pressure. It does not make sense that the trapped air re-establishes itself every time you reach a stop sign.

Another possibility is a heater valve that is stuck partially closed.

 

[Zero Six LE]

I think you have an obstruction in the line that feeds the heater core. This effectively blocks the core when the water pump is at low output (idle).

The hypothesis that air the core is the issue is at odds with itself. Trapped air can be in the core, but it blows out with increased water pump pressure. It does not make sense that the trapped air re-establishes itself every time you reach a stop sign.

Another possibility is a heater valve that is stuck partially closed.

I would say it's either air in the cooling system or a bad water pump. I'd start with the air theory first.

 

[vedder012]

well let me add this....after they fixed the oil leak i got home and noticed it now had a fast antifreeze leak...took it back to the dealer and the tech didnt tighten up a clamp on one of the hoses..this could be key to how the air got into the system.....?

 

[ffips]

Would it make sense to make some sort of "winter sticky" about burping the air bubble?

 

[colin123]

I think you have an obstruction in the line that feeds the heater core. This effectively blocks the core when the water pump is at low output (idle).

The hypothesis that air the core is the issue is at odds with itself. Trapped air can be in the core, but it blows out with increased water pump pressure. It does not make sense that the trapped air re-establishes itself every time you reach a stop sign.

Another possibility is a heater valve that is stuck partially closed.

what the op described its pretty much exactly what happend to me with my z. i started noticing the heater didn't seem to blow as hot when not moving but thought i was just crazy. then it got to the point where it wasn't blowing hot air at all when at idle (i was out of town for work so i didn't have time to take it in). on my way back from my trip i noticed that when at idle the temp would rise from what it normally sat at so i pulled over and checked the overflow which was reading full. i stopped at the nearest nissan dealership i could find the master tech after listening to everything told me about how the routing of the coolant lines and position of the overflow tank and the position of the heater core makes the heater core much more of a high spot than it normally should be so when the system settles down with lower pressure the air tends to collect there instead of going to the overflow. he used a special filling device that helps pull the air out as he topped off the system with coolant from then on it worked perfect again. he said that come winter time they get alot of people compaining of this. 95% chance its just air that he has.

 

[Offspring22]

I'd say so - woulda made it easier for me to fix last winter - but I 3rd, 4th, (where are we at?) over filling the coolant tank. Fixed it for me last winter - been toasty warm every since.

 

[CT_Nismo]

what the op described its pretty much exactly what happend to me with my z. i started noticing the heater didn't seem to blow as hot when not moving but thought i was just crazy. then it got to the point where it wasn't blowing hot air at all when at idle (i was out of town for work so i didn't have time to take it in). on my way back from my trip i noticed that when at idle the temp would rise from what it normally sat at so i pulled over and checked the overflow which was reading full. i stopped at the nearest nissan dealership i could find the master tech after listening to everything told me about how the routing of the coolant lines and position of the overflow tank and the position of the heater core makes the heater core much more of a high spot than it normally should be so when the system settles down with lower pressure the air tends to collect there instead of going to the overflow. he used a special filling device that helps pull the air out as he topped off the system with coolant from then on it worked perfect again. he said that come winter time they get alot of people compaining of this. 95% chance its just air that he has.

I think with certain geometries, it's possible for the heater core to be a "high point air trap." I have not heard this to be true for the Frontier. The air should pass out of the system in due time.

Let's see what the OP learns from Nissan on this issue.

 

[Jordo]

Ive have noticed this in my truck too. I bought it in April of this year, so now is the first time I have been using the heater. And mine, when I stop at a light will blow less hot then when on the throttle. It is not cold, but only warm. When I'm moving it is like "liquid magma" (insert Dr. Evil's voice)! But like CT Nismo said, I THINK I could start stop in a 20 ft section and get the same worm, hot condition. I have been scratching my head on this one for a few weeks.

I'm guessing I can search this??? How to blead the heater core?

 

[Offspring22]

Seriously people, with so many people stating to over fill the coolant to solve the no heat at idle problem - why is there such debate? Should we start a list of who this has solved the problem for so far? Has anyone NOT had the over filling the recovery tank work - and even if so, is it not at least worth a shot?

 

[ffips]

Hi, I am ffips, and overfilling worked for me.

 

[colin123]

hi i'm colin, had the dealer ship do it on my z and since then i've kept up on it on my z and my fronty by overfilling if i notice it get cooler when at idle and that has worked for me.

 

[vedder012]

Today I overfilled the recovery tank with fluid and so far so good. It's constantly blowing out heat. Thanks zerosix and everyone else for helping me fix yet another dealership mistake...

 

[Zero Six LE]

Today I overfilled the recovery tank with fluid and so far so good. It's constantly blowing out heat. Thanks zerosix and everyone else for helping me fix yet another dealership mistake...

You're welcome. Glad you got it done. Heat is nice sometimes.