My heat doesn't work until I turn the temp up to 85 on my auto climate control.

It's cold from 65 to 84, then at 85 it gets warm.

My car does run really cold, well below the halfway mark on the temp gauge. But it has always run like that.

I haven't used my heater in a few months since it's still pretty warm at night, now it's cold in the mornings, I noticed that it doesn't blow hot until 85.

Does anybody know why this is doing this? Is my car just too cold?

 

mine is set to 75, in the mornings, it usually blows cold air, until after the engine gets warmed up, it could take some time before the air gets warm.

 

Mine still blows cold after 40 minutes of highway driving all the way up to 84.

 

I have the same problem with my '00. Hopefully someone knows how to fix this.

 

Have you had your dash apart lately?

I had this issue with mine about 2-3 years ago. It was either one extreme or the other. What had happened was when they replaced damaged dash parts (for warranty work) they bent the pins on the sensor behind the slots on the right side of the wheel.

My guess would be that sensor is fubared. If you have the ESM, there is a troubleshooting guide in there that will tell you what sensor is bad (I think, it HAS been a few years). You get to play some games to see some things. Its really easy to do and gives you either the exact thing that wrong or really close.

 

There is a tiny dot on the temp gauge. When you reach op temp, the needle should rest over this dot. Is it? If not you might have cooling/thermostat issues.

 

My moms 00 SE has this same problem, and hers is completely virgin. She was the orig owner, it has never seen a single mod, no panels have been taken apart, and the only work done has been at dealerships.

But I do have the service manual...Ill do some reading and see what I can find, and report back if I find anything.

 

is your temperture gauge stay constant after warm up?
if it drops when in a going traffic and raises when stop then yr thermostate might stuck open....

 

Take a look at the post on the link below. It describes a diagnostic process that allows you to troubleshoot your climate control system. It should help you figure out what the problem is.

I had this same problem with my I30. I ran this diagnostic and found that the intake sensor had failed. I bought a new one for about $10.00, took apart my dash (it is located in the blower unit), and installed it myself. Problem solved.

Let me know if you need any further explanation.

http://forums.maxima.org/showthread....e+control+cold

 

No change in temp or gauge location from a few months ago, I guess I haven't tried it since I took my dash apart to wire up my Sirius...

I'll check it tomorrow.

 

take it off Auto and press Econ

heat should work just fine

 

from what i understand, the heat comes on at 85+ but not below, and is drastic, rather than gradual. which leads me to lean towards a sensor.

try running the self diagnostic.

 

Correct, and its not only a drastic change...at 84 degrees on auto, it still blows cold air, even in the middle of winter. (Shes had this problem almost a year now)

My moms car is 2 hours away, so I cant really troubleshoot in person very well right now. So if anyone wants, I can send a copy of the heater/ac section of the service manual, so someone can better troubleshoot. I only ask that you post up the results and solution. PM me if interested.

 

HERE IS YOUR SOLUTION:

I had the EXACT same problem. i replaced the tiny sensor that sits downstream of the evaporator behind the glovebox area. I think it's called the "intake temperature sensor" (though the name doesn't fit the function). You can get it from DaveB for about 10 bucks. the sensor measures the air going through your vents and if it's bad (mine was reading 130 degree air with AC on!) it screws up the climate control's "brain."

Fixed the problem.

Only thing...it is a MAJOR PITA to get to....really.

EDIT: Didn't notice his post above...^^^

 

Its all good, the more posts confirming this the merrier. Good to know a 100% solution, and that it isnt expensive.

 

Don't suppose you have a write-up or how to?

 

basic:
-take out glovebox (there are 2 screws at the bottom on the sides and 4 where the latch is)
-take out every screw and bolt you can find under the dash.
-unhook the little white electrical connector down there (small one) on the left side of the passenger footwell...the wire from it leads to the sensor inside the air box

The goal is to "open" the area near the transmission tunnel where the black part of the air box joins with the clear/translucent part (you'll see what I mean when you get down there). The sensor is on the far side of the evaporator grid, and i couldn't figure out a way to open it wide enough to get my hand in there. I ended up:

1. improvising using variuos tools (needlenose pliers, screwdrivers, pry bar)
2. breaking part of the plastic box (got frustrated)
3. cutting up my hands in several locations.

All in all, one of the most frustrating and PITA installs I've ever done (and I've done alot of them), all to replace a $10 sensor.

 

Thanks for the how to. I followed the instructions for the diagnostic test that was linked up above, but it only came up with code 25, and that was probably because I was in the garage. Did you do the diagnostic test prior to diagnosing your problem? If not, how did you know what needed to be changed. Also, is it possible to have a bad sensor even though it wasn't picked up by the test. Thanks again.

 

yes I ran the diagnostic...the most notable part was when you can check the current temperatures of all 3 sensors (exterior, interior, and vent temps).

Mine said:
interior: 73 degrees (felt about right)
exterior: 68 degrees (felt about right)
vent ("intake"): 131 degrees with cold AC air coming out (umm....not right).

That was the tipoff for me.

Did you check the three sensor tempuratures using the diagnostic?

 

I haven't check that test yet. My wife is at work and she drove the car. I will check 1st thing tomorrow. Thanks for the info.

 

That is incorrect. Heat will work with "Auto" on as well - I run "auto" all winter since the moisture is removed from the heated air, thus no window fogging when it's cold out.

Auto means that the air conditioner is on (which can also blow hot) as well as the evaporator.

Econ means the conditioning is off, thus no evap.

 

I did this test today and got basically the same readings that you did, including the vent (intake) temp. One question though...The diagnostic is done by 1st pressing and holding the off button. You said that it was 131 degrees with the AC on. How can the AC be on if you have to do the test by first turning it off?

 

it turns it on real low to take the measurement, or uses the "last" reading. Either way, it shouldn't be 131 degrees ANYWHERE in the car.

 

I guess I will be ordering a intake sensor. Thanks for the how-to and for your help.

 

I replaced following these guideleines and it worked great. BUT, before I changed, I did hook the new sensor up to confirm the high temperature reading was OK. The biggest problem was removing the old sensor, as it's on the far side of the evap core. I spread the housing apart and cut a small wood block to hold it open (Remember) remove as many of the screws as possible to prevent damage. Then used a LONG screw driver to slowly pry the old sensor out. A little at the top, then at the bottom. I'm not sure why leaving the old sensor in place is not an option. When installing the new sensor, install on the side opposite where it was installed before as I could not get a hand or pliers to install on the far side. The evaporator core should have the same temp across the entire back surface as long as you stay in the air flow...

 

ok, so I have the same exact problem with the ac blowing cold air from 65-84, then hot air at 85. I just replaced the temp sensor and i still have the problem. any ideas on what the problem could be?

 

I actually traded in my Maxima before I ever got the problem fixed.