A/C compressor.

Does anyone know what could prevent the AC compressor clutch from engaging? I've checked the fuses related to AC in the main panel and they are all OK.

I havent had a look in the mysterious 2nd fuse panel over on the passenger side but will check tommorrow.

if your waiting for the engine note to change when switching it on, it could be that the system is low on gas or worse, got a leak and gone totally flat .this is what has happened to mine

I'm watching the compressor when im turning the a/c on and off... when the compressor clutch engages the centre of it will start to spin instead of just the outside of the pulley.

AFAIK being low on gas won't cause the compressor not to spin... it's most likely some electrical fault... there was a how-to on that hilux site for fixing bad earths in the AC controller... I wonder if hte 'ace also suffers from this?

Hi, If your system is low on gas the compressor/ clutch won't cut in at all. There is a pressure switch that will stop clutch engaging if there is not enough gas/pressure in the system.
Dill.

The air con only works with the blower on, also it will switch off & on to maintain the temperature. The engine revs should also increase when the a/c compressor clutch is engaged.
Also it is vacuum controlled, if you remove the drivers seat/ floor panel, you will see the 2 vacuum pipes attached to the electrical switch.
I suspect it is something simple possibly the vacuum pipes/ vacuum pump. Are the brakes OK? The vacuum pump on the alternator drive gives your brakes the power.

When I first read that... I was like wtf vacuum pump?? Then I remembered it's a turbo diesel!... they make boost at idle!

The revs don't change at all when switching the AC on and off (with the blower on)... I just found the idle control solenoids were all piped arse about but that doesnt seem to have changed the idle at all.

I'll have a look at the pump but judging by the brakes the vacuum is fine... if anything the brakes are too touchy! If I can locate that solenoid I can test it out and see if the problem is electrical or pneumatic.

Thanks for the info!

HI There,

I found on my previous car with A/C, that it didnt work and the A/C compressor clutch did not engage when the A/C button was pushed. The problem was a leak in the system which meant there was not enough pressure to activate the pressure switch. The pressure switch is linked to the electics which control the A/C clucth engagement. Basically the pump is supposed not to run with insufficient gas pressurein it. As per previous post regarding Pressure switch.

Martin

Hi, the vacuum system is just to operate the engine idle-up system (raises the engine idle speed when the A/C in on to compensate for the extra load on the engine), it does not controll or have any effect on weather the compressor cuts in or not, the idle-up system will operate when the compressor cuts in, not the other way around. You really need to get someone to put some pressure gauges on the system and start from there.

Just to clear something up (from Abaddon's last post) , diesels have a vacuum pump because they dont produce their own vacuum, because they don't have a throttle butterfly like a petrol engine. Not because they produce boost at idle, they dont, non turbo diesel engines also dont have any vacuum.
Before anybody corrects me, The 1kz-te does actually have a type of throttle butterfly but it is wide open when ever the engine is running, it only closes (and produces vacuum) when you switch off the engine. (this is the release of gas noise that you here a couple of seconds after the engine stops, the noise is the butterfly opening again). This system is there to make the engine shutdown smoother unlike older diesels that come to a stop with a big thud (because of the high compression). Hope this makes sence to everybody.
Cheers Dill.

Hi , I do car air con for a living and generally the Hiace has a excellent a/c system.
Sounds like yours could have a leak and has cut power to the compressor through the hi / lo pressure cut out switch. For a quick DIY check you can hot wire the compressor to the battery to see if it cuts in and runs and hold the bigger diameter alloy line going to the comp and feel if it is getting cold .This is the suction line , the other smaller diameter line is the discharge line and gets very hot so be careful. If compressor is running and the line is not cold it is low on gas and has a leak somewhere.
If the suction line gets cold you could have an electrical problem.
Pretty hard to tell without gauges but good luck.
cheers tony

Tony I have a question, our aircon works well and at idle or low revs cuts in and out without any noise but anything over 2 thou it gives a squeal at cut in. The belt feels tight enough and seems to be sitting in pulley OK.Any thoughts ?