Luke717

Air conditioning fault Corolla HB 2020 ?

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I've had my new Corolla for exactly one week, thrilled to bits so far! A delight to drive.

Today was the first lengthy trip as opposed to the short journeys I've done so far. 130 miles, a lovely warm sunny day, great to get to know how the car is on this kind of trip, mostly motorway. Only one thing not good - the air conditioning doesn't deliver chilled air as you'd expect.  The setting's as it came from the dealer with the A/C lit, the setting for air to front seat areas lit. Turn the car on, air comes out of the vents.

I guess because today is the first longish trip and a warm day, it's the first time I noticed this - lots of air coming out of the vents but not cooled, just ambient. Temp set to 20; if I dial it down to 17 or 16, no difference at all. It makes no difference if the system is set to Auto or Dual. Not only that, but I noticed that the light under the A/C button kept going out. If I pressed the button, the light came on. But after 2 or 3 minutes, it went out.

It seems to me that this must be a fault. I can find no information  in the manual. Googling the term gives me no useful results. I see nothing at all in the MID menus. So I guess this means a call to the dealer. Mentioning it here, though, in case anyone has any insight as to what it might be or what I can do to investigate it.

Appreciate any advice, thanks.

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Are you using the dealer supplied, abbreviated owners manual or the full owners manual which you can download from My Toyota?

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Just now, FROSTYBALLS said:

Are you using the dealer supplied, abbreviated owners manual or the full owners manual which you can download from My Toyota?

I've got the full manual, a 668-page PDF I downloaded from the MyT area on the website. There is a section on the air conditioning system starting on page 476. But it's a how-to explaining what each setting is, what the switches are, etc. I didn't find anything there that helps me address my issue unfortunately.

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On my car if you dial down the temp as far as possible so it shows "Lo" (and not a number) then it blows chilled air. On a really hot day and in a baking car it can take a couple of minutes to begin to feel the benefit but it does work. Seems to me that if you are setting a temperature like 17 then that is soon going to be reached so maybe that's why it cuts out so quickly?

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24 minutes ago, Velvet--Glove said:

On my car if you dial down the temp as far as possible so it shows "Lo" (and not a number) then it blows chilled air. On a really hot day and in a baking car it can take a couple of minutes to begin to feel the benefit but it does work. Seems to me that if you are setting a temperature like 17 then that is soon going to be reached so maybe that's why it cuts out so quickly?

Thanks for this suggestion. It's most interesting, if not really intuitive. I wonder why this isn't explained in the manual. In my experience with other cars, you dial in a temperature number and the system delivers cooled air that I imagine matches the number or something close to it. I get 'Lo' but how is the car's system determining what 'Lo' means?

But I will try it! Thanks for the tip.

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On my Avensis, the lowest temp is 16°C.  After that it shows LO.  The difference is that if you set it to 16° or higher, the HVAC controller will get it to the dialled in temp and keep it there.  If one sets it to LO, there is no lower limit.  The system will just keep pumping out chilled air.

If one sets their heater to Hi, the opposite will happen i.e. it will keep pumping out unlimited heat.

When I put the A/C on, I can feel chilled air from the vents after only 5 seconds.

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If the light under the A/C button goes out after a few seconds then that suggests a fault. Possibly low gas. Back to the dealer....

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Never had the light from the ac button go off, would be a good idea to check it out.

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9 hours ago, Stivino said:

On my Avensis, the lowest temp is 16°C.  After that it shows LO.  The difference is that if you set it to 16° or higher, the HVAC controller will get it to the dialled in temp and keep it there.  If one sets it to LO, there is no lower limit.  The system will just keep pumping out chilled air.

If one sets their heater to Hi, the opposite will happen i.e. it will keep pumping out unlimited heat.

When I put the A/C on, I can feel chilled air from the vents after only 5 seconds.

Yes, @Velvet--Glove suggested similar. I do wonder, though how the car system defines what Lo and Hi are. But I will try it!

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@mrfixer @King Crimson that's what's been going round in my mind - however this is supposed to work, surely the A/C light wouldn't go out. That would mean the system is off, right? I am going to try out others' suggestions re Lo and Hi. But, I will call the dealer. Thanks for your comments.

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As well as being a tell-tale that the air conditioning is switched on unlike say, a heated window tell-tale, the air conditioning light is also an indicator that it is working satisfactorily - this aspect of the light's operation is not similar to all the other dash indicators.

For example, if refrigerant the gas has leaked out, then the tell-tale will not come on at all - it's effectively a simple 'diagnostic pass' light.

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The A/C system will only have one output temperature. The outside air temperature (or cabin if you're on recirculate) will impact the vent output temperature somewhat as it mixes with the A/C output but the vents can basically only blow air out at one of two temperatures: Ambient or whatever the compressor is capable of.

The cabin temperature is regulated by switching the compressor on or off and adjusting the fan speed. This will eventually lead to the cabin temperature oscillating between <some value above> and <some value below> the actual target temperature. 'Lo' will just run the compressor forever so eventually the cabin will be down to whatever the A/C output is.

I have noticed that modern cars don't seem to cool as aggressively. The first two A/C cars I had - Honda Civic then a Jazz - had an arctic blast coming out of the vents. But the cars I've owned over the last ten years seem quite lack-lustre. My guess is that modern efficiency demands mean they have small compressors and perhaps the A/C output isn't as cold. With my last couple of cars it was sometimes unclear if/when the A/C was actually blowing cold whereas the first two you'd be worried about getting frostbite.

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With a weather of around 38 - 40 celcius i keep the ac on at 23 celcius at the eco mode, the cabin cools nicely and the ac doesn't make a lot of noise unless i of course increase the fan speed, it usually takes about 10 seconds for the cabin to cool down

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If you have the aircon on but set the temperature to 20.C then you will not get much chilled air. The system is trying to keep a constant 20.C inside the cabin. The aircon light coming on and going off would suggest this is exactly what the system is trying to do ie, keep a constant 20.C May I suggest you set the temperature to low with the aircon on. Go for a drive and see if you get very cold air coming through the vents. The aircon light will stay on all the time with this setting. If the aircon light goes out when set to low then you may have a fault.

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I can confirm that the Air con light stays on if you press it, and won't go out until you switch it off, regardless of whether it has cooled ( or warmed) the cabin to the set temperature.

Light going off of it's own accord suggests a fault.

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29 minutes ago, Timmon said:

I can confirm that the Air con light stays on if you press it, and won't go out until you switch it off, regardless of whether it has cooled ( or warmed) the cabin to the set temperature.

Light going off of it's own accord suggests a fault.

I agree.  The light in the switch is just a reminder that you have the A/C switched on and it neither confirms nor denies that the A/C is working.  The only thing it confirms is that the little bulb inside the switch works.

If it is flickering or going on and off, either the switch or the bulb inside it is faulty, nothing else.

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8 hours ago, AndrueC said:

I have noticed that modern cars don't seem to cool as aggressively. The first two A/C cars I had - Honda Civic then a Jazz - had an arctic blast coming out of the vents. But the cars I've owned over the last ten years seem quite lack-lustre. My guess is that modern efficiency demands mean they have small compressors and perhaps the A/C output isn't as cold. With my last couple of cars it was sometimes unclear if/when the A/C was actually blowing cold whereas the first two you'd be worried about getting frostbite.

I'm learning more about car air conditioning than I imagined I'd need to 😉

My previous car, a 17-plate Ford Focus Titanium, had air conditioning that, when you dialled a specific temperature, produced cooled air that I guess was close to that temperature. Pretty instant too. My car before that, an 06-plate Audi A4 SLine, was the same. If you dialled the temp right down, you would get that Arctic blast. What I'm understanding in this thread is the air con in a Toyota Corolla isn't like that at all.

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2 hours ago, Timmon said:

Light going off of it's own accord suggests a fault.

That's what it seems to me too. It did that again today. I have the car booked in with the dealer in a few days, hope to get to the bottom of this.

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8 minutes ago, Luke717 said:

air con in a Toyota Corolla isn't like that at all.

It should be

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Hi, definitely something wrong with the air con. The green light should stay ON all the times when air con is turned ON no matter if the compressor works or not, if there is no gas in then will light up for a,second and goes out, or no light at al and the compressor will not start.  When settings are at Low use a thermometer and put it on the vents and readings should be between 4C°to 6C°. You can also ask the dealer to open another Corolla for comparison., only compare at the Lowest settings, not actually temperature like 20-22 or whatever degrees. 
Good luck 👍

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23 hours ago, Stivino said:

I agree.  The light in the switch is just a reminder that you have the A/C switched on and it neither confirms nor denies that the A/C is working.  The only thing it confirms is that the little bulb inside the switch works.

If it is flickering or going on and off, either the switch or the bulb inside it is faulty, nothing else.

The light going out could also be an indication that there is a fault. In the USA, 2018 Corolla users have reported this, as have other Toyota model owners.Usually indicates the compressor is not firing up. If it is just the switch led, should be easy to fix, but since the Air con does not seem to be working properly in this case, sounds like the system is not firing up.The switches only send a signal to the computer, they don't do any thing physical locally, like they used to in the good old days.

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2 hours ago, TonyHSD said:

Hi, definitely something wrong with the air con. The green light should stay ON all the times when air con is turned ON no matter if the compressor works or not, if there is no gas in then will light up for a,second and goes out, or no light at al and the compressor will not start.  When settings are at Low use a thermometer and put it on the vents and readings should be between 4C°to 6C°. You can also ask the dealer to open another Corolla for comparison., only compare at the Lowest settings, not actually temperature like 20-22 or whatever degrees. 
Good luck 👍

As low as 4c? Wow. That's a lot lower than I'd expect and makes me wonder if my A/C is working properly. The most I've ever felt coming from the vents is a chilly breeze. 4c should make me fear for frostbrite.

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3 hours ago, TonyHSD said:

Hi, definitely something wrong with the air con. The green light should stay ON all the times when air con is turned ON no matter if the compressor works or not, if there is no gas in then will light up for a,second and goes out, or no light at al and the compressor will not start.  When settings are at Low use a thermometer and put it on the vents and readings should be between 4C°to 6C°. You can also ask the dealer to open another Corolla for comparison., only compare at the Lowest settings, not actually temperature like 20-22 or whatever degrees. 
Good luck 👍

Hi Tony, thanks for adding to this discussion. Today I experimented with dialling down the temp to the LO setting as others have suggested. It got slightly cooler air from the vents but absolutely not chilled air at all. All the system is delivering is ambient-temp air from outside. Someone previously mentioned getting Arctic air at the LO setting. Well, not in my Corolla! I have the car booked into the dealer on Thursday, thanks for the tip re comparing with another Corolla, let's see what transpires.

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Hi, yes should be chilly cold air coming out the vent when settings are at low, the description of the issue sounds like low gas pressure, something that usually happens after years of use without regas, but could be compressor fault or something else since light comes on and goes out after a while, plus it’s a brand new car. Dealer should be able to find and fix the issue for you. We did recently regased our two old Toyota’s, my one ac was good, but the other one similar to yours, mine took less gas than the other, now both cars has an icy cold AC.
Regards 👍

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4 hours ago, TonyHSD said:

Hi, yes should be chilly cold air coming out the vent when settings are at low, the description of the issue sounds like low gas pressure, something that usually happens after years of use without regas, but could be compressor fault or something else since light comes on and goes out after a while, plus it’s a brand new car. Dealer should be able to find and fix the issue for you. We did recently regased our two old Toyota’s, my one ac was good, but the other one similar to yours, mine took less gas than the other, now both cars has an icy cold AC.
Regards 👍

Appreciate your insights, thanks.

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