Nissan 3.0TD Patrol - Aircon sensor on dash

Submitted: Sunday, Feb 08, 2004 at 19:51
ThreadID: 10366 Views:4173 Replies:5 FollowUps:4
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I was travelling back home from Perth the other day and stopped on the roadside to speak with some people. Left the car running with the air on [fresh as it always is] and up to that time it had been very comfortable and maintaining a constant temp.

Outside temperature was probably about 50 celsius but it was getting later in the day and cooler than it had been. {Was about 4 in the afternoon}

In other words it had been hotter earlier while driving along up to when I stopped. [between Minilya and Nanutarra in NW WA]

After about 15 minutes I finished having a yack and went back to the car to keep on driving. I noticed the cabin area was quite a bit warmer than it had been but thought maybe it was something to do with a rev cutout or something and expected it to cool down after I got going again. Water temp gauge was in its normal place and so I was a bit surprised.

It got a bit cooler in the cab after about 10 minutes but certainly nowhere near as cool as it had been and not enough to be considered effective.

Thought it might just need to completely shut down and let it cool a bit so called into Nanutarra [where diesel costs the most of any place between Perth and here - how the hell can $1.30 litre can be justified escapes me and I would not fill up or buy stuff from the food shop on principle] and let it cool down for 30 minutes while the kids had a walk around in the river bed area.

Got back in the car and but still no more effective. As it got later in the day and cooler outside then the airconditioner became more and more effective.

Got home that night and thought no more of it. Went out again in the hot of the day and the blasted thing is doing the same thing. Went out last night and it was fine again.

In checking out the Owners Manual to find out if there is a thermal cutout when a certain outside temp is reached I saw talk of a airconditioning sensor on the dash, It is a red flashing light.

Mine was covered by the dashmat that was put on it before I picked it up from the dealer. Until today I had no idea it [the sensor] was there. There is a punch out hole in the dash [that had not been punched out] that would expose that flashing light which is right in front of the drivers seat position near the windscreen on the top of the dash.

Can anyone tell me What this sensor actually does and could that be the cause of my problem?

If not anyone got any idea what it might be. I can't get it into the dealers for 3 weeks and its bloody hot up here at this time of year!!



I've posted in a couple of forums so if you answered else where I will see it. Don't waste your time doing the same thing twice - thanks.
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Reply By: Roachie - Sunday, Feb 08, 2004 at 21:29

Sunday, Feb 08, 2004 at 21:29
G'day Dave,
This is my 2nd attempt to answer this question for you. The first one ended up with the site crashing and my lengthy response "lost" somewhere.
So here goes again.....
The light on the dash is to show the NATS is activated (ie: Nissan Anti Theft System); nothing to do with air con as far as I know.
The air con switches off on my 4.2T/D (2000 GU) when the cooant temp in the bottom radiator tank rises to a certain point and triggers a switch. There's another switch on the opposite side of the bottom tank which, when the temp goes a bit higher again, switches on the air con fan (but not the compressor), the idea being to add to the cooling system's effectiveness.
On my truck this only happens when the temp gauge goes up to or past about half way. There has been a lot written about this in previous posts on this forum.
I have serious doubts about the accuracy of factory temp gauges. It would be damn nice to know what the temp is, rather than somewhere between C and H.
Also, the fact that you noticed it after the vehicle had been idling for a while, doesn't surprise me. The cooling system actually has to work harder when you're standing still, because there is no air-ram effect.
AnswerID: 45908

Follow Up By: Moneypit - Sunday, Feb 08, 2004 at 22:27

Sunday, Feb 08, 2004 at 22:27

I thought the same thing about the light [being for the immobiliser] but on reading the owners manual on page 3-8 it says " The sensor on the instrument panel [and there is a picture of the topview of the dash and an arrow pointing at the flashing light I talk of] helps maintain a constant temperature. Do not put anything on, or around, this sensor"

I had a feeling that a lot of other Nissan drivers are going to be outside cutting out the little punch hole in the dash mats.

I don't think I'm getting any closer to the answer although I have no doubt it was initially started by the temperature getting to high. Trouble is it does not work effectively now on any hot day. Thats what is concerning me.

FollowupID: 307887

Reply By: flappan - Monday, Feb 09, 2004 at 09:06

Monday, Feb 09, 2004 at 09:06
The temp sensor is on the passenger side . . .
AnswerID: 45952

Follow Up By: Roachie - Monday, Feb 09, 2004 at 09:14

Monday, Feb 09, 2004 at 09:14
As Pauline Hanson once said....."Please Explain".....
Where abouts on the passenger side? In the cab/on dash or under the bonnet?
I'm learning heaps from all you other blokes (and sheilas too I s'pose).
FollowupID: 307912

Follow Up By: Brian - Monday, Feb 09, 2004 at 10:54

Monday, Feb 09, 2004 at 10:54
There is a blanking plate on the passenger side of the dash, same place as the flashing red light but on the passenger side! Is this the one ?????

FollowupID: 307918

Follow Up By: Roachie - Monday, Feb 09, 2004 at 11:27

Monday, Feb 09, 2004 at 11:27
I don't know for sure, but would assume the blanking plate would be where the same blinking red light would be located on left-hand drive models?
FollowupID: 307924

Reply By: GUPatrol - Monday, Feb 09, 2004 at 14:02

Monday, Feb 09, 2004 at 14:02
The sensor in question is only available in the TI version, the TI has climate control and it uses a sensor to measure the difference between the inside temp and outside temp.
The ST uses a capilary inside the evaporator compartment (behind the glovebox).
UNlike the 4.2, the 3.0L model uses the engine ECU to control A/C compressor and fans however if the A/C is cooling (just not effective) you got to look at something else.
Looking at your description of what happened and the outside temperatures I would guess that the following may have happenned:
The A/C system has a condenser (outside in front of the radiator) which needs to be cooled down when the outside temperatures are high, if not cooled down the pressure buildup gets too high. To protect the system (should the pressure increase above a threshold) there is a fuse (not an electrical one) that allows some gas to escape, if that happens the system no longer performs, so if you are going to be parked in excesive heat, turn it off, not designed to idle for a long time...
Does it work OK first off? when you first start it?
The other problem which occurs is as follows:
If the system has been operating for a long time on high humidity areas, the evaporator (Inside the cabin), builds up a lot of moisture, which at times start to freeze, the more it freezes the less the capilary can measure temperature, and the more it freezes again, when this happens air cannot flow through the evaporator and no exchange takes place. Solution is to turn it off and wait to defrost, if it is OK first thing, that is what the problem is.
Anything other than that could be the capillary not working properly or the TX valve not working properly, both diagnosed by attaching pressure gages to the system.

Hope this helps...
AnswerID: 45979

Reply By: jeff-wa - Monday, Feb 09, 2004 at 15:25

Monday, Feb 09, 2004 at 15:25
I agree with money pit, I would say it's a combination of your air con "icing up" and the fact that you had no air comming through the front of your car to take the heat away from the air con. The reason it took awhile to start working again was that you kept the air on switched on so the ice did not have a chance to melt until you let it sit for a few hours off. Switch it back on once the ice has melted and drained away and HEY PRESTO it works again.
So if it's working fine again now, I wouldn't worry about it.
AnswerID: 45999

Reply By: Michael_FNQ - Monday, Feb 09, 2004 at 20:40

Monday, Feb 09, 2004 at 20:40
I am no expert but I do know that airconditioners with the new R134A gas have problems with high head pressure in the system if there is not sufficient airflow over the condensor in high temperatures. If you have too many accessories (lights, intercooler) and at idle (especially on fresh air) on a hot day then the pump will just turn off but will automatically start again when the pressure drops.

I have seen a 100 Series with auto oil cooler and aftermarket intercooler fitted sit at idle in 35 degree heat and have the air con pump cycle in and out due to excessive head pressure. This can be fixed by dropping the gas pressure slightly but you would want this done by an expert!
AnswerID: 46050

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