Air conditioning behaviour at low temperatures

[74hct04]

Hi all,

 

My current car is the first I have had with A/C. During the summer months, I would press the button, hear a slurping / hissing noise for a few moments (no more than a minute, perhaps) as well as the distinctive noises of the A/C clutch and cooling fan. After a few more moments, the airflow would start to chill. A little while later, the clutch dropped out and fan shutdown until the A/C cycle repeated.

Unfortunately my car was mostly off the road between October and December so I didn't run the A/C (to maintain the system's seals).

I recently tested the A/C in ambient temperatures of perhaps 8C. What happens now is that the hissing / slurping doesn't completely go away (although higher engine revs make it quieter) and the compressor and fan keep running (the engine performance is also slightly reduced - exactly as it was in the summer). The A/C pipes under the bonnet remain at around ambient temperature (and, from outside the car, the compressor buzzes slightly at idle revs - I am not overly worried about this bit).

I read somewhere that automotive A/C doesn't work below about 9C but is this what others experience - a continuous hissing / slurping and the air not getting chilled? I have a couple of weeks of my warranty remaining so would appreciate any input - even a spell for warmer weather! ;).

Thank you,

R

[Cjohnston1982]

The a/c should work down to about 2c ish after which the compressor won’t come on. It probably won’t be able to chill the air much if it’s cold outside but it can be used to demist the car (with the heater on too). 

How old is the car? As long as the compressor comes on then I wouldn’t worry too much.

 

[74hct04]

Thank you very much for your reply, Craig.  I am worried that running the compressor without full pressure isn't a good idea. The car is a late 2011 model and I've no evidence of a regass in the service history. I spoke to the dealership this afternoon who have booked me in just 2 days before the warranty expires. They claim that some loss is natural and regasses are occasionally required - hmm.

I have been careful to request a full investigation but we will see what actually happens.

This morning (ambient about 8C), I got the interior nice and toasty then switched to recirculate and hit the A/C switch - still no change :(.

I need to confess that it's actually a C1 rather than an Aygo. I recognise a couple of members from C1OC and have been a long-time lurker here as it tends to have a good technical croud (I am an Engineer and probably one of the most technically minded fans of these little cars). I hope I haven't broken any rules...

If someone could test the A/C of an old-style Aygo and prove it *does* work in cold weather, going cold and quiet I would be very very grateful and will feel a lot better about potentially handing over a wedge of cash to the dealership.

[Micra2Aygo]

Did a wee test this morning on my early 2011 aygo

Outside temp was 1.5C  and on pressing the AC button........Nothing

A 5 min drive and pressing the AC button  you herd the usual compressor clonk and hiss and the AC fan whirr noises but as the outside temp was so low there didn't seem to be a difference in what came out of the vents, I wouldn't expect a change at such a low temp anyway.

If you do need a regass then Kwik Fit in the past have had offers over the winter for AC regass  ( £30 rings a bell)   My old micra had non- working AC, nothing happened when the button was pressed and they diagnosed the there was a leek ( the machine does a pressure test before the regass) and as they don't to repairs there was no charge.  Best check your warranty small print as it may allow for a certain amount of "leakage" 

good luck!

[74hct04]

Thank you so much for trying this. Did the hiss continue as mine does or fade away?

I will have a look for quik fit offers.!

[Cyker]

IIRC the Aygo's aircon is a bit weird in that when you turn it on it doesn't actually turn on in certain situations; IIRC if the car is under acceleration load it won't run for instance, and if it's been running for a bit it'll switch off for a bit then switch back on again after a while.

I assume it's to save fuel instead of running it continuously and 'wasting' fuel or sapping power form the engine when actually want that power for making the car go forwards 

Well, I say just the Aygo, but I think my New Yaris has a similar system too; When I turn it on I don't feel the air getting particularly cold or the engine note changing or any drag on the car's performance which I'd expect to be very noticeable on such a weak engine.

I have noticed it cuts in more noticeably if I am coasting in gear towards e.g. lights. It certainly doesn't function like the AC in my old D4D - When you pressed the AC button on that car, it came on so hard I could use it to help slow the car down on e.g. hills so I wouldn't have to brake or downshift so much!  Had surprisingly little effect on fuel economy too! I'm curious how New Yaris's will affect it come summer (Must admit I'm not optimistic given how much this new engine hates any kind of load!)

 

 

[74hct04]

Cyker,

Thank you for an interesting and informative post. Was the Aygo you had the first generation model (2005-2014) ?

[Cyker]

Err, sorry, no all my cars have been Yarisususesises!  My main experience with the Aygo aircon was when I had one as a courtesy car, and technically I think it was actually a C1, but back then the 107, C1 and Aygo were actually the same car anyway...
 

[Micra2Aygo]

11 hours ago, 74hct04 said:

Thank you so much for trying this. Did the hiss continue as mine does or fade away?

I will have a look for quik fit offers.!

Did another round of tests       dont know the actual ambient temp but Torque had the air and engine temps at 6C   

On pressing the AC button I get a clonk and hiss that lasts for a second or so then the whirr of the fan  masks any other noise.  The interior light dims for a few seconds as well.

Surprisingly did notice a temperature difference when driving when the AC was on or off.  Got the interior nice and warm then slid the temp selector to cold, it took a min or so for the air out of the vents to be fully cold.   Got the car warm again then slid the temp selector to cold and switched on the AC, the vents went quickly cold and the air did seem colder. 

In summer months I do notice that the AC does cycle on and off and at 70mph or so you can feel a slight dip in speed when it kicks in. Don't notice it at low speeds but do hear the compressor clonk.  On the Micra if you were at low speed and pressed the button the car noticeably slowed and the accelerator peddle did drop slightly as the the car was trying to adjust for the  extra load.

AC does need to be used to stop the seals from drying out, the gas in the system also has oil mixed in and that keeps things lubricated.  If its not used then the seals dry out and the gas escapes.  Worse case is if the now dry seals then perish and then after a regass the AC will work for a short time but the gas will escape again via the now perished seals. 

The Micra had an actual leak as the AC radiator needed to be moved slightly to allow the engine radiator to be replaced. The mechanic (a neighbour helping out) thought he managed to replace the radiator with out disturbing the AC radiator to much,  but it was months later I noticed that the AC wasn't working. Thankfully the sun roof still opened  

If your dealer does offer a regass then haggle with them, they may drop their price especially if they have a regass machine on site and they don't have to take the car to an local garage that does. 

[FROSTYBALLS]

4 hours ago, Cyker said:

.....back then the 107, C1 and Aygo were actually the same car anyway...

As they are now, only differences being the front and rear styling.