Im trying to figure out why my heater is not blowing out hott air. I have an 02 i35 3.5 motor. The A/C works fine, but the heat does not. Coolant in radiator and tank are full, and its not overheating at all. I have the automatic climate control, when i turn it all the way to 90 degrees the heat comes out, but not as hot as it should be. Now on my 4th gen the heat will fry you at 85 degrees, so i know these cars have really hott heat. Even on 80 its still warm, but does not stay warm or not at capacity. IM hoping its not a thermostat issue.

 

You may have air in the cooling system. Try burping the system first before moving onto more complex (and expensive) fixes.

 

ok i will try that first and see if that helps

 

In the dash by the ignition switch is a little air intake grill for the climate control. Make sure that this is not plugged up or blocked by something.

If the cooling system is OK, run the self diagnostic on the HVAC controls. See page 36 in the FSM for the how to run it and interpret the results.

http://boredmder.com/FSMs/Infiniti/I35/2002/HA.pdf

 

When car up to temp, check the in/out heater hoses and if one is hot, coolant is restricted, but f both are hot, coolant is passing through and most likely your air mix door or intake air door are the issue. Possibly an air door motor._____________

 

Yes thanks for the replies, I drove the car today, I noticed the when turning on the heat/ turning the dial on the climate control, I dont hear anything such as a door moving/ closing. Anyone know where the air mix door is located. THe heat comes out for about 2 mins and then cool air just comes out. But i will see if both heater hoses are hot, i dont believe air is in the system though.

 

The air mix door is located located just about dead center in the air duct box, just above the transmission hump. The motor that runs it is attached to the bottom of the duct box, just above the ECU.

if you are getting heat for a minute or two and then it stops, that does not sound like a air mix door problem to me. If the link from the motor to the door has not come off, that door will not move by itself.

Run that self diagnostic. I think that one of the temperature sensors is bad.

This photo is a view from the driver side foot well. You can see the linkage between the motor and the door better from the passenger side.



This is a view from the passenger side foot well.

 

thanks for those pictures man, If the air mix door motor is working would i be able to see it open and close/ move if i look directly at it while changing the climate control. I will look into this today, and try to run the diagnosis.

 

Yes, you can see the arm move when looking from the passenger side.

The ignition switch will have to be ON for power, but the engine does not have to be running.

 

ok thanks man gonna try and see what happens today with it.

 

ok while i was doing my tune up yesterday, i messed around with the climate control, manually moved the air mix door while they key was in ingnition. At first it was not moving while going from cold to heat. After i started the car. I saw the door open and close. So I drove down the highway at 70mph turn on the heat on auto setting at 90 degrees, it blows out really hot, on both auto and manual mode. I was surprised, it didnt do this before. So I left the heat on and see how long it was gonna blow hot heat. And as soon as i park the car let it idle the heat stops blowing and only cool air blows.

 

That sure sounds like you have air trapped in the engine or the radiator is not full.

 

I will prob try to bleed it and see what happens, the coolant tank is full, and the radiator is pretty full, just not full to where you open the radiator cap and coolant splashes out

 

The radiator should always be full to to the very top, so fill it up.

Jack the car up very high in the front (or park on a steep hill). With the engine cold, start it and rev it some (like oscillating). This should start blowing the air pocket out of the heater core. You want to make it bleed fast b/c you'll start blowing coolant out as the engine warms. Check to see that your heat works at idle. Put the cap back on, fill the reservoir and you're done.

 

ok i will fill the radiator and try to bleed it on a hill and hopefully that will get all the air out.

 

I forgot to mention that you obviously have to let it warm some so the thermostat opens and the air can escape. But it's usually pretty obvious when bubbles start coming out before it fully warms up and the coolant starts overflowing like crazy.

I've never had a problem bleeding a VQ like this in 2 mins flat.

 

ok great because i thought it would take a lot longer to do, but good to know. I tried bleeding it a few days ago but i didnt park it on a hill, just let it idle for a few mins and put the radiator cap back on.

 

Clogged heater core, faulty thermostat (check your rad hoses whem warm, a cold one means bad thermo) or crazy as it sounds glycol mixture can affect this pretty harsh, pure coolant wont even get barely luke warm

 

Also listen for your blend door moving as your cycle thru your hvac options, if you cant hear it thats probably the issue

 

At first I thought that might be the problem, so i checked it to see if it moves when i switch from cold to heat, it was moving. So if i bleed it real good and it still does it, then im leaning more towards thermostat. As long as im driving the heat comes out, but as soon as i get ready to park/ let it idle for a few mins/ no heat just cool air. But I will say that its gotten better and hotter the times it does come out lol, so something im doing is working.

 

ok I think i have narrowed it down to a thermostat issue. But im not sure, I let the car warm up with the radiator cap off. I filled up it last night with coolant to the top/ didnt take much. But the bottom radiator hose was still cold even with the engine fully warmed up. Heat still not coming out at idle or if it does its jus warm for a few seconds then cool. Im assuming the thermostat may be in wrong or not opening when it should? Plus the coolant looks orange in the radiator but green in the tank. But if the thermostat is faulty, How is the car still able to fully function?? It does not run hot by the way, and it only takes like 10 mins tops for the car to reach operating temp. My 93 max had a faulty thermostat but it would blow heat when at idle and parked, would not heat the car as long as it was moving, and the temp guage would go down to below normal operating temp. So im confused.

 

Some moron put dexcool in it... If it was the old crap, then it has probably clogged **** up. I haven't personally seen it, but I've heard the stories from the people that mixed dex and regular coolant and sludged the whole cooling system.

T-stat is irrelevant to hot air as long the engine warms. Sounds like radiator and heater core are clogged.

 

looks like ive got my work cut out for me this weekend lol, looks like ill have to drain and flush the system smh. Oh well i love to work on my own car anyways.

 

you may be right, because everytime the fans come on, they are on full speed.

 

I would drain the radiator and see what you find inside to start with.

The heater hoses are easy to get to. One side should be hot and the other cold (since your heat isn't working). Blast water through the cold side and see if gunk starts coming out.
If there's crap in there then you really need to flush everything extremely well.

 

Great idea, I will definetly do that this weekend. I do get occasional heat like while the car is in motion, but once its been sitting/ park or idle no more heat.

 

So i finally got to the bottom of my heat problem. I discovered there are no drain plugs on the raditor, so I let car warm up, then drove a few minutes, let it cool shut it off. Took off the radiator cap carefully, ran the engine, turned on heat full blast. There was alot of air trapped in there, So i raced the engine a few times, added coolant ect until the air bubbles stopped coming out. SO i turn the heat on 90. It is too hot now! lol even sitting at idle it is still hot/ sometimes too hot!. But problem solved, thanks for the help guys! Now on to replacing these cat converters.

 

Congrats on getting to the root of the problem and getting it fixed.

 

THanks man, and to think i did this while it was raining at the car wash last night lol, im glad it was something simple though.

 

I thought you already bled the system

 

I inicially thought i bled it but the coolant level was low, and i didnt let it warm up all the way on the first try. So the second time it was obvious that i didnt have enough coolant in the radiator.

 

You must have had a lot of air in there

 

I dont know, but i still can hear water moving around in there sometimes.

 

Keep checking when cool and see if there's air in the rad.

 

If you can, park the car with the front end elevated. That will help let the air get into the radiator.

 

ok i will try that again tomarro, but it seems like the coolant level in radiator drops a little, but the level in the resorvior stays the same, like the system is not sucking anything to compensate.

 

A video on youtube shows how to bleed air from coolant. It works great after you bleed system.

 

If the radiator level goes down, but the reservoir never changes, this would mean that there is a leak in the cooling system somewhere, allowing air in so that the cooling, contracting water cannot create a vacuum to suck it out of the reservoir.

A bad radiator cap could be letting air in, but it wouldn't necessarily allow the coolant to leak out. A hose would be a more likely cause.

Do you see any indications of what looks like mud being splashed on the engine or anywhere under the hood? This is what anti-freeze looks like when it dries on the engine. Also, check the radiator, around where the top tank is attached to the cooling fin core. The radiators have a habit of leaking.

 

you have a good point man, I will have to check the hoses to be sure there are no leaks, and just plan to replace the radiator sooner or later anyway since they are not too expensive.

 

ok i will watch that