Air-conditioning issues

Our tech guru has the answers to your car questions
by Ferman Lao | Jan 18, 2014


Good day, sir Ferman. I have learned a lot from your online column and have been a subscriber to your magazine for three years now.

Something is bothering me: The Toyota Innova V has an "A/C" button, while our Innova E has none.

From my understanding, the A/C button switches the aircon on and off. What confuses me is that, I can also turn my aircon on and off in our Innova E by setting the fan speed to off or the temperature to lowest. My question is: What's the difference between turning the aircon on and off via the A/C button and doing so via the fan speed and temperature buttons?

Was the A/C button created to make things simpler?

Thanks and more power, Top Gear Philippines!

Patrick Julaton


Hi, Patrick. I don't remember how the HVAC controls in Toyota Innovas look like. However, your description of the E model's switch gear reminds me of how most aircon controls had been like for years before the advent of electronics.

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One mechanical switch controls the fan speed by regulating the amount of electricity getting to the fan, while another controls the temperature. The temperature control switch also happens to incorporate the off switch for the aircon compressor. It effectively turns the compressor on and off as needed, controlling the temperature by turning on the A/C compressor once a certain threshold is reached (or off when another is) to maintain the temperature you've set for the passenger compartment.

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More modern HVACs are now controlled electronically, making it a little more precise compared to the older systems. It also allows for individual settings for the driver and the passengers. I don't really know why the A/C compressor activation was given its own switch, but it seems to me that it's for the convenience of the occupants. You no longer have to keep resetting the temperature to what it was before, as you only need to hit the switch to turn off the A/C. Another reason would be to make it a little more reliable as you no longer have to subject the rotary switch to unnecessary wear when you want to have the blower on but the compressor off.

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In a way, I suppose that it does make things simpler for the vehicle's driver and passengers. It's one of those things that we as car owners and consumers don't really think about or question, and just take for granted until someone asks.

I hope I've answered your question.


My A/C died again for the seventh time, and Mazda replaced the blower under warranty, again. After having it changed, it died again last year for the eighth time. However, it was no longer under warranty as expected.

So I brought it to NAA, owned by Mike Cheng. I don't know if you remember him, but he was a former Ford/Mazda dealer. They cleaned the A/C and replaced several parts, including the blower. Then, after another four months, it broke down again.

After doing a thorough review, they found the culprit: the connector that connects the A/C blower to the wiring harness was loose. They "fixed" it again, and it was fine for about two weeks before dying again. I just got it back, and the verdict is that it comes loose after usage.

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My main question--and I would really appreciate the help here--is: Where can I source the connector? It is a part that is not carried by the dealerships. And if you order one from dealerships, it takes about six weeks and you need to get the whole harness (really expensive at around P35,000 plus P17,000 for labor). I've consulted Rey's Auto Electrical, and I was told that they could fix the issue if a part could be sourced.

 Is there a shop here that specializes in this part? Would you know anyone in Yazaki Torres? I recall they used to supply Ford Philippines with the harness.

Thanks a lot!

Paolo David


Hi, Paolo. It's unlikely that you can source the connector or harness from Yazaki Torres without going through the normal supply chain.

Anyway, given that the vehicle is already out of warranty and the dealer (I'm assuming) has not been able to address the problem properly prior to the warranty's expiry, I would not have any issues taking a different route to fixing the problem.

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If it were my car, I would talk to Rey's Auto Electrical and ask them if it would be possible to just bypass the supposedly faulty connector altogether. I would have them cut the wires before the connector or connectors, and fit a new set of terminals and connectors--a set that hopefully will not be as prone to loosening as the existing one.

I certainly would not want to shell out the cash to pay for the harness, which should've been replaced under warranty to begin with (if that is really the problem), nor the labor cost involved to do so.

Now, I can't say for sure if what I would have them do is actually easily doable, as there are many ways an electrical connector can be made. But if it is, then I certainly would explore the option after I'm made aware of what some or all of the possible drawbacks might be.

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Definitely, the harness or the car as a whole won't be as original as I would've preferred it to be, but I wouldn't have any issues having such a conversion done if it were my car.

Of course, you might not have the same sentiments. If you decide to have your problem fixed by modifying the car in such a manner, it may or may not cause other problems, which may not be so evident at this point in time. The electrical shop you've talked to should be able to inform you more on the possible issues that may arise with such a conversion.


Best regards,

Ferman Lao
Technical Editor 

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