Disable AC when defogger on?

[vaxterra]

Does anyone know a way of preventing the AC from coming on when the defroster/defogger is on? This is on a 2003. It turns off when you turn the fan switch off, but even if you use the vent, it comes back on until the ignition is shut off.

[Schludwiller]

You'll have to dig into the forums for that one. It's there somewhere. It requires disconnecting some wires, not just turning something on or off.

[OffroadX]

I don't know just how applicable this is to the new 2002 dash, much less the new behavior of the 2003 system, but you can ty this:
http://mywebpages.comcast.net/xterra/tech/defrost.txt

Brent

[xterri]

The method described herein sounds soooooo complicated.

Is there any other way to disable the AC on DEFROST? By the way, the manual states that AC control should turn back to normal operation once the fan switch is off and the selector is off of the defrost....but this never happens, unless the ignition is turned off. So many times have I put the car on neutral and turned the car off/on!!!

[HangGlider]

Originally Posted by vaxterra

Does anyone know a way of preventing the AC from coming on when the defroster/defogger is on? This is on a 2003. It turns off when you turn the fan switch off, but even if you use the vent, it comes back on until the ignition is shut off.

If I am correct, you are having a problem which I have too. When you switch the air control to vent, it SHOULD shut off the air conditioner. I have put my car in neutral, shut off the engine and restarted it MANY times now in order to shut off the AC. This is a dangerous pain in the neck. I took it to the dealer (it was about 2 months old) and they "supposedly" fixed the problem by replacing a micro switch in the dash. Nope. Aint fixed. I don't want to waste any more time with the dealer, so I just live with it. But I can say for sure that this is NOT the expected behavior.
(I also have a 2003)

[OffroadX]

The 2003 system engages the compressor when any setting of the knob to the right of vertical is selected, and it will not shut off regardless of mode selected until the engine is shut down. This is by design to prevent the moisture that has condensed on the evaporator from being released back into the cabin and causing a rapid, severe fog-up.
Some have found some Xterras that have a glitch that makes the compressor run all the time, regardless of mode selected, even if you start the truck with the dash vents only selected etc. and this is not the correct behavior and should be persued to the top if necessary. "khs" on XOC has much information about this.

Brent

[HangGlider]

Unbelievable. My dealer must be a real dipshit. If this is the correct behavior (I am not doubting you at all), you'd think a dealer would know this. Since so many have had this issue, it rings true what you say about moisture on the evaporator because that was a frequent thing that happened to me in previous vehicles (before I got the coolest ride I have ever had!).

PS...can someone take a look at my post in the FAQ forum regarding hot (warm really) air coming out of the vents when the thermostat is turned all the way down? The thermometer on the rear view says 62 F, yet I have to turn on the AC or open the windows...

[OffroadX]

There are TSBs on both topics:

AC/defrost operation change for 03:
http://www.nissan-techinfo.com/nissa...ssan/54301.asp

Warm air from the vents, there are newer cowl pieces:
http://www.nissan-techinfo.com/nissa...ssan/53899.asp
Or just pop your cowl pieces off and poke/drill the holes out fully yourself.

And please note that the FAQ section is not a place to ask questions, it is a place to provide answers to Frequently Asked Questions.

Brent

[HangGlider]

If you want to disable the microswitch in the 2003 model, it is a little different than the descriptions above. After removing the plastic around the stereo etc., you will see two green wires that connect the microswitch to the circuit board. The microswitch is normally closed when the knob is NOT in the defrost position. When the knob is in the defrost position, the switch is in an open status. The easy solution is to solder a bridge between the two green wires. I put a picture of the exposed wires at
http://users.adelphia.net/~jrs99/images/ACMOD.jpg

Now I am in control of my AC!!!!

[xterri]

Here is my ...

Reading the Xterra 2003 manual, the part about the A/C, it states that the A/C will not automatically turn on when the dial is on defrost mode IF THE OUTSIDE AMBIENT TEMPERATURE IS COLD. This means that there is a thermostat or thermo sensor somewhere on the car, which desables this automatic feature when the outside air temperature is cold.

Now, does anyone know where this thermometer/thermostat might be?

By fooling the thermostat sensor, making it think that the outside is cold (possibly by removing the sensor or shorting it), this might work. Then again, those 2 green wires mentioned in the previous post might just be those sensor wires that I'm thinking about.

Does this sound right? Anyone know where that sensor is located?

[OffroadX]

The ambient air temperature sensor is mounted right dead center behind the grille on the radiator support upright, to the right (your right as facing the vehicle) of the horn.