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I drive a 1.3 liter 2009 Toyota Corolla. I'm the first owner of my car. I've never ever touched the AC/compressor/gas. Everything is genuine. But I have this weird problem with the a/c where it stops cooling when I try going above 80kmph. The a/c cools just fine under 80kmph. But when I go over 80kmph, or accelerate above 2800rpm, it stops cooling. And once I go under 80kmph, it starts cooling again.

Would appreciate if anyone could come up with a solution. Thanks!

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    A number of vehicles override the A/C compressor under a certain % of throttle. Is this a new problem or has it always done this?
    – Zshoulders
    Mar 30, 2017 at 15:49
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    @Zshoulders Interesting, I've never heard of that before (because what happens at idle?) I was wondering if perhaps the higher RPMs were causing an overpressure situation in the compressor, causing it to open a bypass which would inherently prevent any cooling action in the cabin.
    – Hari
    Mar 31, 2017 at 20:40
  • @HariGanti Sorry, the language in that might be confusing. I meant 'under' as in "under a certain condition," not "less than." Wide open throttle will disconnect the A/C on some cars. The idea being that you need all the power you can get at WOT. There is usualy some throttle percentage that will cause the A/C clutch to disengage, depends on the car. OP's situation seems low for a cutoff, but 1.3 is a small engine. His car might be above the throttle % needed to cut the A/C at 80km/h. I don't know much about internal compressor workings but what you say makes a good deal of sense
    – Zshoulders
    Mar 31, 2017 at 20:56
  • @Zshoulders My apologies! Glad we do agree, however, and that it was just a simple case of poor interpretation. Because most AC compressors are belt driven, their power input varies wildly with engine conditions. My guess is that they're "tuned" for cruising RPMs, but capable of generating enough pressure at idle as well. This, however, means that at higher RPMs, they are overdriven, which can lead to an overpressure failure, thus a bypass valve would be needed to compensate (like a wastegate, in a way).
    – Hari
    Mar 31, 2017 at 21:01
  • @Zshoulders I have been facing this problem from last year. Last month my car mechanic recommended me to change the clutch plate. Is there any connection between clutch and that weird a/c problem?
    – Huzayl WS
    Apr 1, 2017 at 15:06

1 Answer 1

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You likely need to charge the AC in this vehicle. Over time the refrigerant can leak out of the AC circuit. That is the leading cause of a reduction in cooling capability. The system can get a pressure test to confirm that condition.

AC compressor disengage is a computer driven event. The AC pulley pulls horsepower off of the engine from the serpintine belt and it is assumed that you were doing wide open throttle for an emergency acceleration at which point you do not want any additional loads on the engine in that situation.

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