Byzii

Car's A/C during winter

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Hey everybody,

Have run into a bit of an issue with the car's A/C system. It was working fine for the past year or so, then the car was sitting in a warm garage for 2 weeks for clutch master and slave cylinder replacement, and now the it seems there's an issue with A/C working in below-freezing temps.

Now it's mostly below-freezing temperatures in my country so most of the time the A/C doesn't turn on, meaning - when I press the AC button on the console (doesn't matter if in AUTO mode or not), I can just feel that the compressor clutch doesn't engage - simply nothing happens. And I can keep hammering the AC button for hours and it won't engage. It also doesn't matter if the car is warmed up or just started.

Now, one day it was around +2 Celsius and for the fun of it I pressed the AC button - lo' and behold, I feel the clutch engaging and feel the AC starting. But here's the catch - it seems to be "grinding" more than it did for the past year. The grinding is nothing too bad, it's just louder than it was. But the whole drive belt area is kind of grinding even with AC off, I guess one of the pulleys is going bad.

 

To make a long story short - how is it with Toyota's AC systems in winter? Is it possible that a sensor detects the ambient temperature is below freezing and thus simply doesn't engage AC at all? I can't remember from last winter if it worked or not.

Or maybe it's a problem with freon gas? I'm guessing it's the same as with tyre pressure - once it's below freezing, the gas compresses and there's "less" of it - and so AC doesn't engage so that the compressor doesn't get damaged? I guess in this case it could be simply an issue with refrigerant amount.

Hope you guys can help me out here before I consider where to take the car. I guess removing the drive belt and feeling the pulleys could work but is it possible that a problem with AC pulley somehow doesn't let the clutch engage?

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Yes , when air temperature below 0 the air con will not start , it’s a norm for any car don’t worry. If any grinding noises coming from your serpentine belt it’s likely wet due to a cold damp weather and salt that most likely been spread on the road. I don’t know if the belt is auto tension or you may have to adjust manually, you can have look yourself and adjust if you need it. It’s also a good idea to service your air con if you haven’t done so in the last two years but outside temperature should be above 5c at least to do so or even over 10c. 

Good luck 

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You can try the self test method. Look at the following link - 

Toyota/Lexus have had the self test method for a while. This will give you some information for free. Also may give you a clue to the state of your system.

I would find an auto A/C specialist to check the condition of the system, and confirm if the noise is a worn component, or just needed a little clean.

 

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Hey Konrad,

Thank you for the information, didn't know such diagnostic mode even existed.

It gave me two codes, 21 and 24, former being for the sunlight sensor and latter apparently for the solar sensor. I haven't heard anything about such sensors so I don't think my T25 has those things.

The whole thing is difficult to diagnose since sometimes it works, sometimes it doesn't. For example, today just after cold start at +2 Celsius the AC started working immediately, then after driving for around 10 or 15 minutes it suddenly stops working while the car is just cruising. Then sometimes I can start the car, press the AC button and it doesn't engage, I leave the button pressed and suddenly 10 miles later on the road while driving I feel/smell the AC start working. Sometimes it starts and continues working, sometimes it only works for half a minute.

Really strange,  this makes me think the clutch since it can make a rather unpleasant sound when AC is actually working. But again, that sound doesn't appear always and of course when you're with a mechanic it works wonderfully.

Looks like I'll have to live with it for a while and see if anything else related pops up, if not then when the rainy season comes I'll have to splurge for an extensive diagnostics, leaving me without a car for a while.

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