Quick a/c question

[Seeker]

I have inherited my Dad's 1.33 Yaris and I have just noticed the a/c doesn't work.  On cars I've owned before when the a/c is switched on you can hear the a/c compressor clutch operate (with the bonnet up) and the idle speed increases slightly, is the Yaris the same?  I suspect the compressor clutch is frozen or I have a blown fuse/other miscellaneous electrical problem.

 

[Parts-King]

In order of likelihood on the Yaris

1: Low on gas-needs recharging

2: Leak from the high pressure pipe-replace pipe and regas

3: Leak from the condenser-replace and regas 

4: Compressor issues are very uncommon 

A specialist will check for leaks, probably best to seek somebody out who can pressurise and test for you 

All the best 

[Seeker]

Thanks for the info P-K.  At the moment, though, I just need to know if switching the a/c makes any noise from the engine.  I used to live in the US and every vehicle I owned over there (including a Corolla and a Camry) gave an audible "clunk" from the compressor clutch  (when the a/c was engaged) and would continue to clunk on/off if the system was on for a while - just like a fridge cycles.  In addition the idle control valve was called to raise the idle speed (automatically) when the compressor was running.

Also, if you were running at low speed you could feel the compressor kick in as you were driving. Having said all that, switching the a/c on in my Yaris does nothing except turn the (a/c) light on, it may well have lost all its freon, but I think I have other issues too.  So, if someone could just let me know if switching on the a/c makes a noise/raises the idle speed slightly, I'd appreciate it.

 

[Parts-King]

If it is working, you should hear the idle speed increase slightly. If it is empty on gas the compressor won't run to protect it, so listening out for it working is not going to help you. As above, get it booked in with your dealer or a car air con specialist who will be able to run dye through the system and check the vacuum for leaks, if all is OK then it might just need gassing up

 

[m456an]

My yaris had no pressure and avensis had low pressure, I just used the stp kit which also stops leaks and did both cars with some gas to spare. The only way to test it is to check the low pressure. Though ac specialists also test the high pressure and can give an overall indication but the revs would increase even with low pressure on the avensis.

If you get cold air it is working, I would leave it as it is autumn. Though yesterday I used it as car was hot and sun was shining.

[furtula]

Easier way would be just to open the bonnet, and check if a/c engages. AC would be beneficial even in winter for defogging.

Yes, there should be a clunk, but maybe the insulation is good so you don't quite hear it. Have someone push the button while you check the pulleys and see if the electronic clutch engages and the ac starts to spin.

[yossarian247]

On our Auris and Avensis there is no noticeable 'clunk' when the aircon is switched on, but the engine revs do change slightly. Many recent aircon systems have dispensed with the clutch in the compressor pulley, instead the compressor shaft spins all the time the engine is running and the aircon load is controlled within the compressor itself. As a result there is no characteristic clunk sound when the aircon switches on. 

[mrpj]

There is a possibility it has a clutchless compressor drive. I recall my 2010 Yaris did. The flow of refrigerant is controlled by a swashplate, within the compressor, operated electrically by a solenoid.

[Seeker]

Thanks for the comments/suggestions.  There's no change in idle speed or any cold air I just have the light coming on the a/c button.  It is due its service at the end of September, I'll mention it then.