Heater blows cold air at stop lights
 

I got a question about the heater in my 03 sedan. Now that is starting to get really cold in Michigan, I noticed that if I am stopped at a light, and if the heat fan level is high that the car blows cold air. Now I know it is easier for the heater and AC to work while you are driving, but I don't remember it being this bad last year. Has anybody else experienced this?

My heater blows very hot and it's been pretty cold here this past week. It sounds like you may have air in your cooling system.

^+1 on air in the cooling system. Do you hear the sound of running water when you rev the motor?

Crap...I do hear the sound of running water! What is the fix? Is it expensive?

EASIEST FIX EVER!!!! :)

First I topped up to coolant resevoir. I then let the car heat up to normal operating temperatures.

I used the bleeding screw behind the engine, and was able to get some air out of the system and get heat when idling.

I also had to do a second step, as I started to get some more heat then before the 'burp' but it was not enough and did not seem correct.

The other step I did after opening up the bleeding screw and letting the coolant 'burp, was take the rad cap off, let the temp raise to normal operating temperatures and leave the car to idle for about 20 min. I then slowly revved the car up to about 4500, and back down, doing this a few times - and the heat noticably increased and stayed hot at idle.

Its been 2 weeks since I have done this - and it has remained consistant!

MORE INFO:

https://g35driver.com/forums/engine-...loud-boom.html

It's no big deal. If you haven't changed the coolant in 60k miles, you should go ahead and do it while you do this. There is an air relief on one of the hoses towards the back of the engine near the battery. Watch the video bythebay put up on infinitihelp.com on the coolant change service. If you don't want to change the coolant, just unscrew the relief add more coolant to the reservoir and wait for a little coolant to spill out of the relief. That should mean there is no more room for air in the system. Normally, air gets into the system when the coolant reservoir goes empty and air gets sucked in instead of coolant. Good luck, it's a free fix!

So apparently RATED_G beat me to it. He's doing the same thing.

Thanks for the help.

I find it much more effective to just keep the car running at idle and burp the system via the air relief valve every couple min. Paying attention to the heat and making sure the temp doesn't rise too high. In between air burping I rev the engine like above.

!!IMPORTANT EDIT " My car is not overheating at all ---- " My car is driving and functioning great - no temperature rise/drop.


Heat was coming out of the vents cold only when I was idle - As long as I am driving the car around the heat comes out great- it's cranking hot!

Once I idle the car it begins to cool very slowly until its all cold again....about (5 to 10 minutes)

Took the car into Infiniti Dealer - Paid 125$ for flush/fill coolant and 65$ for a full inspection of the vehicle.

They do the flush/fill heat was working fine after I left.

48.Hours Later -- Heat is coming out cold again when I idle - but if I keep driving the heat stays hot!

I have been checking for leaks of coolant around the engine/block/hoses/etc.

Nothing found to be leaking? I hear the "Water gulping" from inside the car while I am starting to begin to drive. I just bought a thermostat I have not installed it yet- however I don't think that is going to fix it anyway - but that is why I am here.

What have all you found to be happening after this? I have searched the forums and found a few good threads and will continue to post this and read more.

Thank you all for any help or time you give me -:confused2:

Joe

Take it back to your dealer. There is still air in your system. They should re do the work again for free since they didnt get it all the first time...or you can follow the advice above to get rid of the air. Make sure that your overflow is to the MAX line as well.

UNLESS you have a heater core leaking...which I haven't heard of anyone with a G35 and a leaking heater core yet...so its not very likely.

Thanks for the response
 

:icon17:

Yeah I don't see any coolant or smell any coolant inside the car.

I have not seen any puddling of any coolant outside the car on the driveway or where I park the car.

The inside of the bay is so clean that I could eat breakfast on the plastic cover of the block.

I really do hope that this turns out to be the issue -

Ill be sure to let everyone know what happens if monday this is solved.
Thank you for responding TollBoothWilly. :thewave:

Take it back to the dealer and say "the heat is cold now" and leave it at that. I wouldn't even say it was doing this previously. See what they say there.


If it's not air in the system, my next step would be to replace the thermostat.

Water gulping...its air inside the heater core

Heater Core...
 

Well if it is in the heater core is it flushed with the entire system also?

What could create the air pocket? What is it that I am doing wrong? The car was sitting for a while before I bought it and no one drove it at all.

My car did this when I first bought it too. Just burp the system using the bleeder valve. I wouldn't pay anybody another dollar. It seriously takes less than 30 minutes and the problem will go away.

Having same issue
 

Logged on today to see if anyone is having similar issues and my '05 G35 sedan was blowing cold air as well at a stop light. Also, my climate control dash goes off but when I push down my pop-up navi system, the banging seems to correct it. Anyone else having this problem?

I am going to check one more time tonight to see if the issue persists and then probably get it checked out.

There is tons of info on the forum - do a search to find the quick fix. x2 (for both issues)

SEE LINK:

https://g35driver.com/forums/general...t-working.html

read the rest of the thread. plenty of info out there.

Went to the Infiniti dealer this morning - had them re-do the flush/fill again.

They seem to have solved the issue - but let me see how long it lasts.

They said possibly did not fill all the cavities inside the block last time they did the flush/fill.

Ill let you know if it happens again... so far so good.

i was just about to start a thread and ask the same thing. guess i'll try this tomorrow see if it works. its -46 degrees celcius in my city, we where the 2nd coldest city in the world next to Sibera lolol. i'm really hoping this works cause im tired of reving my car at lights.

:biggthumpup: Good luck but I took mine to the dealership because I really was not sure if I could go through the process successfully... :dunno:

However this morning I woke up and saw a spot about 3 inches in diameter of coolant.... I dunno wtf is going on anymore... I hope that it was just spill-over from the dealership sitting somewhere on the motor. :confused2:


Later - LET ME KNOW WHAT HAPPENS Though!

Well, I had a coolant flush and still blowing cold air. My climate control seems to be working fine but the guys at the local shop (not an infiniti dealer) warned me before the flush that their pressure test indicated everything was fine. I still went ahead with the flush since it was almost 60k since my last flush.

I heard water gulping before the flush but nothing since. They think it's a problem with the head unit. Now researching about replacing my head unit.

I think the problem with the head units is typically with 03-04 models. It may just be your A/C controls going bad.

Well....
 

The control's or head unit should be fine - they seem that way in my car. :biggthumpup:

BTW my car is an 04' G35 Sedan. I think everything is the same as the coupe.

I wanted to update to say that well, maybe the blistering cold is the reason why we are all experiencing this. :driving:

Maybe the car was not made to stay that hot for too long while it's soooo cold out? Any opinions? :BOUNCE:

My car has 51.5k miles on it...

:confused2: :7:

Im also having this problem. Hearing running water when I start driving the car.
Will try bleeding it.

same problem here did everything everyone mentioned above and still not working on my 05 coupe

you probably need to do it multiple times. Took me 5 or 6 times to get all the air out. Lots of short driving trips between to really get the coolant working through the engine.

First off let me just say thanks to the guys who have posted help suggestions on here and the fine DIY vids.

I was having the same problem and after letting the engine warm up and opening the relief screw I was dissappointed to see the problem continue. However, just repeat this process a few times as Tollboothwilley suggests. It took 5 or so attempts before the heat would blow hot at idle.

work or not to work? that is the question... lol
 

hey guys that whole heat durin idle didnt last more than 24 hours for me.


so seriously lets post some post-bleed response descriptions if you can thanks

at the dealer now.
 

Im back at the Infinit dealership as I type this. I want to take the time to refresh what we are all talking about.

I first had this issue about two months ago and I was surprised however I was more afraid that I might have had a serious issue that could cost me quite a bit of money - that I dont have.

I took the car right away to the Infinit dealership closest to my home and said that if there was anything that was going to be fixed it was going to be done here at the dealership. Who more than to trust than the experts right?

So the first time there I explained to the service guy what issue I was experiencing and that was -- My car has heat but it cools down if I am stopped or idle. My car does not overheat and it does not run cool. The car runs great in fact the issue is just crazy to me. I brought up the fact that I hear the coolant flow through the tubing when I get into it and start it. It bubbles through as I hit the gas and then as the engine begins to warm up I can feel the heat kick in.

The dealer decided the best move of attack would be to flush the coolant out of the sytem and then refill the system in which by doing so they would remove any air pockets or bubbles inside the system. I had faith that this operation would be successful in fixing the situation and agreed to pay the cost of the work. As I waited for them to do the work on the car I remember coming back onto the foums to check to seethe replies of anyone on here that was having th same issue.

I read what everyone had replie and continued waiting to see what the outcome was going to be here. I came back online and explained my results. They had finished working on the car and I checked to see if the heat was working at idle and it seemed to be fine so I left the dealer thinking that it was fixed and my worries were over.

I drove the car for about 2 days until I noticed that the issue was back again. the heat in the car was coming back out cool again and I had to rev the motor in ordre for me to have any decent heat tempature. I took the time to get back on the forums only to come and report he bad news and ask for more help. my only option of course was to take it back to the dealership because I had already had paid for the work to be done and was not giving out donations to the dealership for the holidays.. I NEED MY HEAT WORKING!

I live in Chicago incase no one tended to notice that by reading the side window of my profile. It has been as cold as ice out here with tempatures reaching as low as 7 degrees farenheit. well i was asking my self is this he reason to why my car does not produce heat. until i stepped into my friends 91 civic and it was hotter than Mexico in that thing and i could not beleive it was true. I had an 8000 dollar car producing heat constantly at idle speeds and i had my 36000 dollar car cranking out cold to near freezing temps. i as outraged.

I took the car back to the dealership at about 6:30 am. and was the first and only person there at the dealership waiting for work to be done. now i dont want to get into to much detail about what the service man told me on the morning i returned but it was close to the lines of. "we need to make an appointment" - i told hom that was b.s. and I didnt come for that.

LONG STORY SHORT. They did the flush fill over again.
I drove the car for maybe 3 4 days until I noticed the same dsituation was reoccuring once more and that time was the start of the holidays and then could not bring the car back until today. which now of course i cant wait to see what happens with the experts this time. because I know that I cant afford any miraculos expensive work to have done on my car and would be very upset to hear that something more serious is wrong with my car that i may or may not be able to afford.

Here I am stilll waiting and my fingers are starting to cramp up typing on my HTC DASH - hahahahaha! but i had to do something to pass the time in here. the tv has on some horrible talk morning show with all big mouths and i dont have time to listen to that bulls...

Ill let you all know what is happening when i leave here right away without hesitation to the situation because i want to see if this heat is going to work or if its going to flop again

God help me please...

+1 for heater not heating during idle. It kind of defeats the whole purpose of remote start :/. I will try this fix this weekend, thanks all!

I had my mechanic bleed the coolant lines, and noticed a couple days later the heat is still not 100%. I bleed the lines again and still have problems. I think I have the same situation as you, joealbergo, so let me know how it goes at the dealership.

I posted a couple of weeks ago about cold air also coming in. I had a coolant flush and that seemed to fix the problem. However, I also replaced my head unit since the A/C was kicking on and my CD changer was busted. While the problem wasn't constant, I ordered the JDM head unit and had best buy install a new radio. Since then, no issues with the head unit. Unfortunately, my cold air problem came back. I am going to bleed out some air and see if that cures the problem. I'll report back.

Mine has been blowing cool air lately too. I'm going to try this soon.

So far so good - they did the flush again and I am having great heat.

Let's see how long it lasts..

I have a 03 coupe and when you put the heater on all the way (the fan) it blows cold air , but when you put it like 2 notch it blow hot air. Any suggestion what the problem is ? thanks

Could there be a vacuum leak? Though if that was possible I would have expected the experienced service people to look at it. Just that with the engine running slower cold returns.

vacuum leak won't cause that

you need to bleed the air out of the system still. There is an air bubble trapped. Try opening the bleeder valve (passenger side by battery) while the engine is running at full temp. Open it VERY slowly, just to the point that you can hear air come out. When you hear the air stop coming out and coolant starting to bubble out then close it.

Try it a few times. It solved all the issues we had with my friends Z after we installed his crawford headers.

Nobody mentioned the T-stat, it's this little thing which open and closes coolant to the radiator to regulate the engine coolant temperature. Engine coolant is also used to heat up the passenger compartment. Nobody around here seems to accept the fact that T- stats do fail every once in a while, if flushing and bleeding didn't work the first or second time why not try something else? I wouldn't think that infinity is so stupid to design a cooling system that is so badly designed as of to need to be re bleed every couple of weeks.

My G35's heating was also cooling off substantially when idling in -30c temp, t-stat got changed, problem solved.

did anybody find a fix for this?????? ....sorry to open up such a old thread

Don't be sorry -
 

That is the point of having threads.

Each person had different issues I think through-out the thread.

We looked at a few things.

Thermostat
Coolant (Bubbles or Pockets of Air)
A/C Control Electrical
Radiator
Heater Core

My issue was that it took the Infiniti dealership by my house 3 times to flush/refill my coolant properly before they were rid of all the air in the system.

Once they did that - I never had the issue again through the winter last year.

So far so good - hit me back and let me know what's going on with your side.

Give me details...

See ya bud :)

well i never done a flush/refill i always just checke to c if i had enough coolant in the radiator and the backup little platic bottle thing ..even added a little aF

also just last night i turned my car on and put the heater on full blast and waited till the car was at a normal temp and went and unscrewed the air release holes next to the battery and only steam came out and a solid drip ...so i figure no air in the system .....now im thinking i should just flush my system ,but i cant afford a proffesional so i dont know what to do

and my car is a 2003 just hit 81k dont really know if the antifreeze has been flushed ever !! im kinda scared im goin to make it worst if anything if i flush the system my self

Well...
 

I would have to say that I would not do this on my own.

Coolant costs money and these motors have a lot of "pockets" in the block that must be filled with Coolant.


There are people on the thread that do this themselves but they have experience in doing so or at least the know-how to do it successfully.

It's your call...

i think the thing is that you have to constantly top off the radiator/reservoir every morning for a week or two after a coolant change/flush..
my car didn't overheat or anything, but i couldn't believe how much the coolant level drops after a coolant change and then few cycles...
after a week or so.. the level was steady.. and everything seems good.. :D

What do you mean by top off every morning ... I'm lost ??

you know.. in the morning when the car is cold.
1. open your radiator cap and refill to the top..
2. check your reservoir, and make sure it's at the MAX line in the morning (cold)

i had to do this every other day for about 10 days.. and now the level doesn't move.. i am thinking that i am clear of any air pockets.. (i refilled about half a cup to a cup each time I did refill it.. which really isn't too much)

Yeah thanks for the reply..... I think ima go ahead and just do it with the Diy vid at Infinitihelp and with what you just recommend I think I should be fine .... I'll will repost after the experience

Save the money and have the dealer do it. That way - if it happens again they are responsible and have to do the flush/fill again until they get it right.

Trust me, it took THE DEALER 3 times! not my buddy the mechanic - but the dealership.

i dont know.. if you do it yourself.. it's $25 vs $100 at the dealer..
and making trips to the dealer to top it off is annoying as hell..

checking the level every morning at your garage wastes 2 minutes of your time..
if my case, the dealer would be wasting at LEAST a hour (just on the commute)..

the change is fairly easy..