Montego Murph

iTrader: (1)

For the first time since April or so, I had to use the heater today.
I have the electronic climate control option on the I30.

My trip was 45 miles at highway speed, so I know the engine was at operating temperature. Outside temp was 58 degrees.

The temp gauge was stable the whole trip at 1/3 from the bottom, just like always.

I had the temp dial set at 72, but it was not at all warm in the car. I kept bumping it up a few degrees at a time but no warm air came out of the selected vents. When I turned the temp **** to 87, warm air started puffing out a little bit, and when set to 90 degrees, hot air came out, but when I backed it down to human temperatures, again nothing.

All summer long the air conditioning worked fine and adjusted automatically so I don't think it's the little brain unit.

Since the engine temp gauge reads normal, I don't think it's the thermostat. When the thermostat goes, the temp gauge usually reads all wonky, shoots up when stopped, goes way down when driving, etc.

I checked the coolant level in the tank and it looked fine. TOmorrow when the engine is dead cold I'll open the radiator cap and see how it looks in there.

What other things should I be considering?

One odd thing I observed is that as I turned the temp **** gradually in each direction (I did try this in both AUTO and ECON mode) the blower fan would speed up and down as it should, but the temp just didn't change in the car.

djfrestyl

iTrader: (89)

Do you see any visible coolant leaks? Any service/flushes recently done? If your radiator looks good, then it sounds like some sort of blockage or issue with either the heater core or heater valve. Only when the temp control is wide open does enough warm coolant get to your core to heat up the air.

FYI, putting the same thread in multiple subforums is a

Also, I responded to your PM but never heard back from you....

Montego Murph

iTrader: (1)

DJ -- I havent' forgoten ... just have to push this request past the Ministry of War and Finance! Usually it helps to bring something like this up when she comes home from the mall with a few full bags.

As for what you suggested -- No leaks, no low coolant, and no service or flushes done recently in the year that I've had the car. The original owners meticulously maintained the car by the book, so if a coolant flush was suggested by Infiniti, it was done promptly.

I perused the FSM and found a few pages discussing a self-diagnosis system, so I'll mess with that for a while and then check the valve if I can find it. Maybe it's stuck or something?

What baffles me is that it DOES open at some point -- this tells me that the valve works and is not stuck -- just not doing as it is told. Sort of like osmething fell out of calibration somehow.

And as a side note... I did delete the other post, I just wasn't sure if I had the ability to do it (I did) or if I had to contact a moderator. thanks for the gentle warning though.

Murph

djfrestyl

iTrader: (89)

Only when temperature gauge is wide open do you feel heat. Logically it seems like either calibration or semi blockage or some sort. Just a guess. I'm no pro at cooling systems.

Montego Murph

iTrader: (1)

Well, I ran the built in diagnostic program. Getting a -24 code which means the Intake Sensor (behind the glove box) has a short circuit. I like very specific codes.

djfrestyl

iTrader: (89)

Nice!

DennisMik

iTrader: (2)

I don't know if the Infinity is different, but on a Maxima this is not correct. The gauge should be in the center of the range between C and H.That means the engine is running colder than what it is intended to. If the engine is running cooler than it should, the ECU is making the engine run rich. The thermostat is probably out of calibration, but it could also be the sensor that runs the guage.

Just suggesting another project for you.

Montego Murph

iTrader: (1)

You know, I'm glad you said that, because I too thought that it usually indicated a little higher as well -- but since it wasn't fluctuating all over the place like my Celica and Miata both did when the thermostat failed, I figured I just never really paid attention to it.

Should be easy enough to pull and test in the pot of boiling water, yes?

Montego Murph

iTrader: (1)

Here's what I just learned... thought I'd post this for the benefit of future searchers:

I ran the self-diagnostic test again. I got the "-4" code which points towards a short circuit in the intake sensor. (+4 is an open circuit in same.)

Ran through the whole 8-step procedure just to see what else it would tell me, and I'm glad I did because it pretty much double-checked itself:
Ambient Temperature - 69 degrees. Seems reasonable.
Vehicle interior temperature - 77 degrees. Certainly plausible
Air coming into HVAC box - 131 degrees. I'm not so sure about that one.

There is also a chart one can use to test the resistance of the sensor using an ohmmeter and the reading it gave was spot on.

This is all starting to make sense though. The sensor for some reason thinks that the air passing through the system is 131 degrees, so clearly there is no need for MORE heat in the car and it would not generate any. The thing about heat only coming out at 90 or "max" is probably a safety override thing so that if this happened mid-winter, I'd be able to get heat into the car somehow.

So, it looks like I need a new Intake Sensor. The manual is semi-vague about how to replace it... I'm hoping this does not involve draining and recharging the AC system. Shouldn't be, but who knows.

The mystery on my mind now is "how the hell did this thing wear out?"