Trouble Shooting A/c In R33

[sadr33]

iv had the trouble in my R33 of my ac switching on and the often (but not always) off again after only 5-10 secs of being on (this is in A/C on mode with 18 degrees selected so technically should run indefinately in warm weather as the interior isnt 18degrees before it switches off sometimes). Sometimes it doesnt even switch on.

THo there is no constant situation (like hot or cold ambient) where it runs, is intermittent or doesnt switch on in.

There is plenty of refridgerant as the view glass is nice n green when on and the air is nice and cold.

Iv run the diagnostic mode and no faults.

anybody know what might be the cause of this or experienced it?

otherwise can you access all of the cars sensors via a consult cable and program? im sure that one of the sensors must be shitty and so going outside its operating range quickly and then switching the AC off. Tho its problem doesnt show in diagnostic mode...

Anybody? (i cant go another summer without it working)

I've got the same problem sometimes also. A lot of on/off click clacks that dont seem to be related to temperature eg it will switch off when its hot but stay on when its cold. Its definitely electrical related. Putting new or more gas would just make the on states cool better.

I'm a bit pissed manufacturers dont allow control over an always on a/c state

For example you have 18 degrees and then pressing the down arrow again for temp sets it to "Cool" which is always on. That way we can take any sensors out of affecting anything.

I wonder if there is a way to modify anything to disable the sensors or report an always hot state.

[jjman]

yeah this is my rationale too- some sort of a mod to get it to just stay on when AC is selected.

if it isnt on Auto and its is selected at 18degrees with AC on then it should run indefinately. Which it does when working correctly (my other skyline did this fine).

I might get it this week and put it in diagnostic mode after running the AC as much as i can and then put it in diagnostic mode when it is playing up. Hopefully then the system or sensor that is problematic might show up...

Edited November 5, 2012 by jjman

[t_revz]

Not a good idea.

Running indefinitely will freeze the core solid

If its low on gas the compressor will seize

[jjman]

ah.

cheers for that then.

Is that maybe a reason it is turning itself off that it thinks the core is already cool enough?

or conversely that it thinks the system is overheating?

otherwise do you have any idea what might be the most likely fault to cause this temperamental on-off behaviour (when the AC diagnostic mode indicates no faults...)

it seems to be a common enough problem that im sure someone has resolved it in the history of SAU...

Edited November 5, 2012 by jjman

[t_revz]

iv had the trouble in my R33 of my ac switching on and the often (but not always) off again after only 5-10 secs of being on (this is in A/C on mode with 18 degrees selected so technically should run indefinately in warm weather as the interior isnt 18degrees before it switches off sometimes). Sometimes it doesnt even switch on.

THo there is no constant situation (like hot or cold ambient) where it runs, is intermittent or doesnt switch on in.

There is plenty of refridgerant as the view glass is nice n green when on and the air is nice and cold.

Iv run the diagnostic mode and no faults.

anybody know what might be the cause of this or experienced it?

otherwise can you access all of the cars sensors via a consult cable and program? im sure that one of the sensors must be shitty and so going outside its operating range quickly and then switching the AC off. Tho its problem doesnt show in diagnostic mode...

Anybody? (i cant go another summer without it working)

Cutting out 5-10 secs after startup is typical of low gas usually.

The compressor will suck the suction line into a vacumn and pressure switch will cut out.

Try bridge switch and see if it continues.

Or bridge high pressure switch incase it has a blockage.

[jjman]

yeah i was thinking that. But the inspection glass is nice n green when running n sometimes the AC will run for long periods too...

What is the bridge switch/bridge high pressure switch and how does it work?

[t_revz]

I meant bridge/bypass the switches. Low pressure switch should be in the compressor and high pressure is in the dryer (aluminium canister) near the radiator.

The days it works could possibly due to the vehicles heat pressurising what little gas is left enough to not cut out. Hard to say over the net.

Perhaps get a shop to put gauges on it and ensure there is enough pressure. If so then you can continue troubleshooting.

[jjman]

I meant bridge/bypass the switches. Low pressure switch should be in the compressor and high pressure is in the dryer (aluminium canister) near the radiator.

The days it works could possibly due to the vehicles heat pressurising what little gas is left enough to not cut out. Hard to say over the net.

Perhaps get a shop to put gauges on it and ensure there is enough pressure. If so then you can continue troubleshooting.

ah yep.

too easy, will do.

cheers for that mate.

[sadr33]

If its low on gas obviously there is a leak somewhere. Is it possible to introduce a leak by tugging on ac lines in the engine bay. If so anyone know how long it takes for the slowest leak to loose gas to a point the ac system doesn't cool whatever.

I had a car once that would loose gas every year and no one found the leak even with the dye in it. They wanted 3k to open up the dash. very anoying.

[Bloodnut]

jjman I have a similar problem on my S2 R33 gtst, but it lasts longer. All sensors say it is fine and temperatures being read are fine, but if it is a 35-40 degree day and I put the climate control on when driving it will blow cold for 5 min if on auto or full or up to 20 minutes if fan only on 1 or 2, but then revert to ambient temp air. I assume this is to do with a sensor being OK during diagnostic mode and then buggering up when actually being used.

Another thing I noticed and can't think of why is that the air stays cold for much longer if the car is idling, but if I take it for a drive it will go to warm quite a lot lot quicker. Again, I don't know if this is a sensor playing up. I've tried driving it around until it blows warm, then turning the car off and on and running diagnostics - still all looks normal (no faults, temps all ok).

I wonder if I can cheat the system by leaving the car on diagnostics - 42 (full cold) constantly while I'm driving around? Gonna give that a try today. Anyone got any thoughts?

Edited January 5, 2013 by Bloodnut

[t_revz]

Sounds like its freezing up. Next time either try with fan on max and it will prob last longer. Or when it goes warm, turn the air con off but fan on max. After a minute shitloads of water will prob pour out the drain onto the ground as it melts. There will always be water dripping from the drain but if its freezing it will be excessive

[a2z]

Still chasing the problem of the a/c compressor not switching on at all. it will cool if bridged/bypassed at pressure sensor or at relays. The problem I am thinking it could be is a wiring stuff up in/around the relays, or a sensor I have missed. I have checked sun sensor(windscreen) cabin sensor(dash near steering wheel) outside sensor (at front of car) I have changed and checked the sensor that has the heat sink on it at the fan box (behind glove box). Is there another sensor I have missed? possible on the core under the dash or something. I don't want go and pull the dash apart more if there is not one there. And on the wiring side of the problem could the relays be possible wired wrong. with out a proper/complete wiring diagram I feel I have been running blind with the parts of diagram that are available. I feel I have checked this system over and over still no luck though.

Edited January 7, 2013 by a2z

[a2z]

And another thing. Shouldn't the A/C switch activate the relays when pressed on and off?

[jjman]

jjman I have a similar problem on my S2 R33 gtst, but it lasts longer. All sensors say it is fine and temperatures being read are fine, but if it is a 35-40 degree day and I put the climate control on when driving it will blow cold for 5 min if on auto or full or up to 20 minutes if fan only on 1 or 2, but then revert to ambient temp air. I assume this is to do with a sensor being OK during diagnostic mode and then buggering up when actually being used.

Another thing I noticed and can't think of why is that the air stays cold for much longer if the car is idling, but if I take it for a drive it will go to warm quite a lot lot quicker. Again, I don't know if this is a sensor playing up. I've tried driving it around until it blows warm, then turning the car off and on and running diagnostics - still all looks normal (no faults, temps all ok).

I wonder if I can cheat the system by leaving the car on diagnostics - 42 (full cold) constantly while I'm driving around? Gonna give that a try today. Anyone got any thoughts?

Iv worked out with mine that the AC will actually start running quite well if i just leave it on (18 degrees, AC, 3/4 or full blow).

Initially it isnt too cold but it then seems to start blowing cooler and more consistently after a while and will get really cold after quite a while

No idea why...

Tho the air-con compressor was replaced just before i bought the car and i think it is an aftermarket unit or a non-R33 specific compressor. I wonder how this might be affecting things..?

Edited January 9, 2013 by jjman

[a2z]

I was talking to an auto electrician today and because the air con compressor does not even kick in he said there could be another control unit between the climate control module and the ecu and compressor. I even tried taking the ewcu out of the equation by bypassing it but no change. Does any one know if there is another control unit somewhere or something I'm forgetting to check??

[jamesdt]

Ever get a fix to this a2z? Got the exact same aircon issues. A/c compressor won't cut in unless I bridge the aircon relay or bride two of the 4 wires on the pressure switch on the receiver drier. If I bridge the other two wires on the switch it powers the condenser fan relay.

Everything operates as it's ment to, aircon gets cold when bridged. it's just been re gassed with the correct amount of r134a. The idle increases as it's ment when switching the aircon switch on and off as the ficd relay powers up. there is no signal being sent to the aircon relay to switch the clutch in. Annoying!!

[a2z]

No luck. Still looking for an answer.....

[89CAL]

If you can get it to work by bypassing the pressure switch, then is it likely that your pressure switch is no good? They do stop the AC system running if the pressure is low to prevent damage to the compressor

[PuppaDuck]

Hi guys.

A lot of you seem to be having the same problem as myself. That is, you have ruled out the basics being gas or issues raised in the climate controls diagnostics menu.

The culprit could be the thermister.

This is a temperature probe that monitors temperature of the internals of the a/c unit (the heater core) that is in the cabin behind the glove box.

If the temperature is too cold, it tells the a/c clutch to disengage so it doesnt freeze up. One of the symptoms if this part isnt working correctly, is a random on/off activity regardless of the state of your cars movement, weather, temperature settings, etc.

Nissan says they dont stock the part any more, (Nissan FAST part number is 27675X or 2765XA depending on your car) and with so many people having problems with their a/c, you wouldn't use a second hand one.

It is possible to install a generic thermister (around $50) in a new hole next to it and reuse existing wiring. The original clip has 3 wires in it, one for power and the other 2 are for the readings.

If you replace the original, you have to degas, open everything up, remove the 2 wires from inside the unit. If you instead add a new thermister next to the other, you just drill a tiny hole in the unit, and mount it inside the casing near the heater core. Then reuse existing wiring. As the case stays closed, no need to dismantle and degas/regas. Saves $200.

Others may have more experience in this topic and feedback or corrections are welcomed, including prices and stockists.

[89CAL]

The nissan part number doesnt look right. I can check it tonight if I remember