Outer Limits 4x4 Board

we have a 2002 GU wagon with a TD42 intercooled motor .
the problem is
when you lay the boot in the air conditioning seems to turn itself off.

does the GU have a switch to turn the ac off if you need the power?
if so what turns it back on cause mine can take 10 minutes or so b4 it comes back.
another thought was a vacuum problem and the heater flpas are changing by themselves?
i have just had the a.c serviced and they regassed it and said eveything was ok

anyone got ant ideas??

Normally occurs because the engine water temp increases, and the air con switching off is the first warning, when not watching the guage.

krimnl wrote:we have a 2002 GU wagon with a TD42 intercooled motor .
the problem is
when you lay the boot in the air conditioning seems to turn itself off.

does the GU have a switch to turn the ac off if you need the power?
if so what turns it back on cause mine can take 10 minutes or so b4 it comes back.
another thought was a vacuum problem and the heater flpas are changing by themselves?
i have just had the a.c serviced and they regassed it and said eveything was ok

anyone got ant ideas??

Darren, there should be a switch in the bottom of the radiator (there is one on each side but i cant remember which one it is, possibly the drivers side) that is a thermal cutout for the A/C. Nissan calibrated the earlier ones fairly low and then later released a differently calibrated switch as a spare part, this switch may fix the problem but i would have thought your's being an '02 would have already had the higher temp switch. Maybe a job for the Nissan parts man....

I have the same problem with mine which relates to the engine getting hot.
In hot temperatures, 35+, and heavy driving or towing, the engine temperature goes up. The air con switches off first and you can see the engine temp guage go up. If I back off the accelerator and drive easy, the temp goes down and air con comes back on again.

Keep an eye on the temp guage next time. Take it for a drive on a hot day, find a big hill and give it heaps. Watch the temp guage.

I'm still searching a remedy to fix it as I don't want to spend hard earned dollars on trying to fix things which aren't the problem. I believe changing the radiator to a 3 core will fix the problem.

Do a search as simular vehicles have the same problem. Let me know if you change the cut out switch and it fixes the problem.

I have an 03 3lt GU that turn the A/C of on bumps , the water temp stays the same never moves, seem's to work fine in days under 30c temp also but still intermitant on bumps some times?. any one have an answer? nissan has not a clue on this they keep telling me it's fine
Cheers
DP

cool , looks like its time to bypass the thermal switch and see if it fixes the problem. maybee the switch has failed or maybee the big JPC inteercooler is just restricting the air a little bit more than factory,

now i know where to start looking anyway

guys the air con sysytem is a very easy thing t understand, is the same principles as a fridge, if you leave the doors open it gets hot if you put hot stuff it gets hot if yur in hot conditions it gts hot. If you think about it the back of the fridge is the same as the front of the car, it dispenses the heat from inside if it cant cool down on the outside it has no chance of cooling inside your car

4by wrote:I'm still searching a remedy to fix it as I don't want to spend hard earned dollars on trying to fix things which aren't the problem. I believe changing the radiator to a 3 core will fix the problem.

PWR make a bolt in alloy radiator to improve the cooling capacity, but it isnt a fix on its own, because the air flow through the radiator inst a strong design point on the nissan.

matto wrote:guys the air con sysytem is a very easy thing t understand, is the same principles as a fridge, if you leave the doors open it gets hot if you put hot stuff it gets hot if yur in hot conditions it gts hot. If you think about it the back of the fridge is the same as the front of the car, it dispenses the heat from inside if it cant cool down on the outside it has no chance of cooling inside your car

its nothing to do with understanding the way refrigeration works . heat transfer and a pressure / temp relationship has nothing to do with this problem. i am a refrigeration mechanic by trade but this one has me stuffed as the refrigeration side of things is spot on.

ats4x4dotcom wrote:

4by wrote:I'm still searching a remedy to fix it as I don't want to spend hard earned dollars on trying to fix things which aren't the problem. I believe changing the radiator to a 3 core will fix the problem.

PWR make a bolt in alloy radiator to improve the cooling capacity, but it isnt a fix on its own, because the air flow through the radiator inst a strong design point on the nissan.

i have a fealing that there is no condenser fan on my patrol but i have seen them on other gu's maybe that might fix the problem. another job for the weekend.aswell as pulling the radiator out and giving is a wash

Have you tried bypassing the pressure switches,

If you regassed your system was there a leak, did they find the leak, did they vac out the system or just top it up with gas, contaminated gas will give you all sorts of trouble. but you would know that being a fridge mech.

I had the same happening to my 01 gu tray, I fitted self adhesive foam strips between the radiator and radiator support panel (all outside edges)so as to stop any air flow going around the radiator and had to go through it, also as been sugested pull your radiator out and wash between the fins, I have tryed to wash them while still in the vehicle but it isn't very successful, good luck.
ps it only takes a small temp change to make the a/c to cut out. since I did this Ive had no trouble.

Some GU;s are sensitive to driving lights fitted to a bull bar reducing rad airflow. This increases heat just enough for the switch to operate. Remove lights if fitted and check.

Bazzle

The GU has two sensors on the bottom of the radiator one each side . One for the air con the other I am not sure about.
When the outdoor temp is up and the vehicle is working hard, towing or up long hills the temp rises so the sensor turns the air con off and when the temp cools down it will turn itself off.
I tow an off road van and when the air temp is up, about 35% and I am climbing a long hill the needle starts to rise and the air goes off. When over the top and the engine cools a little it turns back on.
I have learnt to live with it, however if it is really hot and we want the air then I just ease up and travel about 85kph which does not make the journey much longer about 30min on average.
Ron Moon went to the PWR radiator so that he could maintain the speed limit as reported in the 4x4 Australia mag. Feb 2006 out now.

Very very simple fix .. clean out your radiator .. it will be packed full of mud dead bugs, parts from hyundais and kia's you have run over in the past XXX,XXXXKms,

Last year (summer) mine was doing exactly what you are experiancing, early this summer I pullled the radiator out to find that it would have less than 10% of the avalaible surface area able to flow air .. after a few nice gentle washes and a long soak or two it was 95% clear ... on a few days on the way home from work this summer when it has been 45+ degrees, the AC still blows icy cold air ...

That would be my first port of call in the cases above and it was pretty cheap fix as well, the all up cost was about $12 for the 6 pack of carlton draught I drank in the few hours it took me to do the job

Well how come my GU has never over heated or shows any sign of being hot, temp guage moves to normal position,and never moves towing camper trailer,and the A/C works if put on from cold start up ??????? when the A/C works it's bloody cold!,and will work for a short time after a big hit from a pot hole???

Dirty Patrol wrote:Well how come my GU has never over heated or shows any sign of being hot, temp guage moves to normal position,and never moves towing camper trailer,and the A/C works if put on from cold start up ??????? when the A/C works it's bloody cold!,and will work for a short time after a big hit from a pot hole???

In english would be more helpful

I am guessing that your AC will work if you turn it on when you start the motor from cold, but will not work if you switch it on when the motor is up to operating temprature .. but will work for a short period after the vehicle hits a pothole ... is that it ??

Love_Mud Sorry me English is not up to your Standard, hows your Spanish?

Nissan has ? fixed a lose relay on A/C seems to be working fine at the Mo.

Very very simple fix .. clean out your radiator .. it will be packed full of mud dead bugs, parts from hyundais and kia's you have run over in the past XXX,XXXXKms,

this only helps to a point. Ours still gets pretty warm when towing the horse/s in 35*+ weather on big hills. (and the A/C switches off)

I'm starting to think it's an airflow problem, an air exit problem.
I'm going to start experimenting with louvres in the bonnet to get the hot, high pressure underbonnet air away.
In race cars and aircraft, the exit ducting is the most critical area for airflow. Look at old subsonic warbirds like P51's. They vary the radiator duct exit to control flow and temperature.

Air, like water follows the path of least resistance. The radiator frontal area of a GU 4.2 is huge, and yet the things have a marginal cooling capacity (which Nissan deny )
The under bonnet area is a known high pressure zone. Even cars that have front hinged bonnets (eg. Jag XJ6 ) will pop open the bonnet if the catch fails near the windscreen.
So, my cunning plan is to cut holes and have either a series of louvres or a rearward facing scoop or NACA ducts in the bonnet. The only sticking point is getting the missus to allow me to cut up her pretty, unblemished Nissan bonnet for the sake of science. If it works, I'm a hero, if it doesn't, I'm in the dog house (again).

So, if anyones GU bonnet goes missing, don't worry, its gone for a good cause....