Hi, One day it worked - the next it reads

-86 degrees!! (yep - minus 86)

 

My ambient temperture readout now reads as above.... Any ideas which sensor is responsible; The one at the base of the w/screen, or the one in the roof/interior light cluster?

Stolen from somewhere - can't remember where :-

 

300ZX Info - Auto Air Conditioner

The 300ZX has ( can have ) an automatic air conditioner. It's quite a clever system that monitors the outside temperature, the sun load ( how bright it is ) and the high / low ( foot ) area temperatures inside the car, trying to keep them at the set levels.

 

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Auto Air Conditioner - Setting Self-diagnosic mode

 

Lets assume that something lights up on the Air-Con display. If it doesn't then it's faulty wiring or the unit itself. Best you check the wiring for before going to your Nissan parts supplier.

Put the system in self-diagnosic mode. With the engine running and the Air-Con OFF hold down OFF while pressing the AUTO switch for at least 5 seconds.

Check that the Air-Con comes on and SET "00" appears. If not it's more than likely a fault with the OFF or AUTO switch.

You're now in self-diagnosic mode. To exit just press OFF or switch the ignition off.

 

 

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Auto Air Conditioner - Checking the sensors

 

There are a number of temperature sensors that send info to the control unit

 

Ambient temperature sensor

In-vehicle sensor (Upper area)

In-vehicle sensor (Lower area)

Duct sensor (Defroster)

Duct sensor (Ventilator)

Duct sensor (Floor)

Sunload sensor

Water temperature

One of the most useful things you can do is check the readings that these sensors are giving. If the Air-Con system is acting oddly it's more than likely one of the sensors giving odd readings. The readings given are quite interesting anyway but don't have a crash doing this while blasting down the road...

 

Put the system in self-diagnosic mode.

You're now on in the sensor monitor mode. The SET display shows the item you're looking at while the AMB display shows the value. To move between the codes use the HI or LO switch.The codes / possible values are :-

Sensor Monitor Code Item Range

00 Ambient temperature -30 to 45°C (-22 to 113°F)

01 Upper compartment temperature 18 to 30°C (64 to 86°F)

02 Lower compartment temperature 20 to 35°C (68 to 95°F)

03 Defrost outlet air temperature 5 to 70°C (41 to 158°F)

04 Vent outlet air temperature 5 to 40°C (41 to 104°F)

05 Floor outlet air temperature 20 to 70°C (68 to 158°F)

06 Sunload 0 to 900 kcal/h (see note 1)

07 Water temperature 20°C (68°F) or 80°C (176°F) (see note 2)

08 MODE door voltage 0 to 5 volts

09 Internal data Anyone know?

 

 

NOTE 1: The shown figure is one tenth of the kcal/h value.

 

NOTE 2: If the coolant temperature is below 40°C then 20°C is show else 80°C is shown

 

If any of the values vary greatly from the real value then the sensor may be faulty. The Air-Con control unit actually keeps track of faults on these sensors and store the data. This is how to view this data :-

 

 

Put the Air-Con in self-diagnosic mode. Note :You can do this from the step above.

Press AUTO until the SET display reads "50" ( should be 3 presses ). This is the Trouble data memory readout system.

Use the HI and LO switches to move through the error readout data. The AMB display shows "50" if there are no problems with this item, "49" to "01" a problem existed and this is the number of engine start/stops since the problem started and "0" the problem exists now.

On the third digit of the AMD display a vertical bar in the top righthand corner shows a sensor open circuit and a horizontal middle bar a short circuit.

 

Sensor Memory Codes Code Sensor Open Circuit Short Circuit

50 Ambient sensor Less than -70°C (-94°F) Greater than 141°C (286°F)

51 Upper compartment sensor Less than -38°C (-36°F) Greater than 141°C (286°F)

52 Lower compartment sensor Less than -38°C (-36°F) Greater than 141°C (286°F)

53 Defrost outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)

54 Vent outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)

55 Floor outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)

56 Sunload sensor Cannot detect this Greater than 1,534 kcal/h

 

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Auto Air Conditioner - Changing the Upper / Lower temperatures

 

It's possible to set the difference between the upper and lower compartment target temperatures. This can be good if you tend to get cold feet in the car for example. Although the range of change may not seem much it's usually enought to make the required effect

 

 

Put the Air-Con in self-diagnosic mode.

Press AUTO until the SET display reads "40" ( should be 2 presses ).

Use the HI and LO switches to move through values -20 to 20 for °C and -32 to 32 for °F. This number ( displayed in AMD ) is the difference between the Upper and Lower target temperatures DIVIDED BY 10. So the max change is +2°C to -2°C.

 

This stays set until either the next change is done or the power is removed ( e.g. battery removed ).

 

[This message has been edited by AndyP (edited 06-07-2001).]

Andy, I don't think that (other) Andy has the Auto aircon. The auto-aircon system (on the mk2 Z) doesn't have an ambient temperature display, it has a display showing fan power.

 

Andy(GP), is your car a mk1 Z (pre 92)? Are you talking about the ambient temperature display or the temperature setting display?

 

(another) Andy

Good point, initially I assumed it could be one of the error messages, but I've not seen a MK1 Z.

Mine is kind of a hybrid of the two, being mid 92.

 

Still useful info though.

Sorry guys, YEP - it's an 90 import!

And it's the Ambient temperture display/figure...

 

[This message has been edited by AndyGP (edited 06-07-2001).]

The series 1 workshop has pages and pages and pages on diags etc. for a/c on this model. The supplement for series 2 seems a litte slimmer.

 

However, way back somebody posted a link to the on-line manual. Search for that then lookup page HA-112 onwards.

our online manual

 

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UK 92 TT White

Mongoose K&N AVCR

KYB Eibach

Craig,

Could you make an official link to this somewhere ? I think it would save a load of searching. Unless of course there's some legal/copyright reason that would make it unwise to do so.

been undecided about putting it officially live for various reasons

 

but i guess it's okay

 

any problems, email me...

 

it'll be in the tech section

 

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UK 92 TT White

Mongoose K&N AVCR

KYB Eibach

Seen this a few times before.

 

Your ambient temp sensor is faulty or maybe disconected (do you still have your stock front bar?).

 

The thermometer works on resisitance, when the sensor is disconnected or damaged, it reads infinite resistance, and the lowest the climate control can read is -86, so that's what it shows. In theory if you were to short it, the ambient guage would show the hottest value it can (if it doesn't wreck something!).

 

The ambient sensor is located on the inside of the front bumper, accessible via the centre nose panel if you have the stock air box removed. When after market bars are put on inexperienced installers forget to reattach the sensor to the new front (or, relocate it somewhere stupid, like touching an oil line so ambient temp reads oil temp!!)

 

Anyway, I'm going all over the place here Bottom line: your amb temp sensor is missing or faulty.

 

Ben

www.aus300zx.com