[Diesel lover]

Hello members!

I own a 2012 Dzire with a 1197 cc K series petrol engine mated to a 4 speed torque convertor automatic transmission.

It has a very strange behaving AC. When moving at crawling speed (when no accelerator input is needed) in stop go traffic (say in a traffic jam) or while reversing, the AC cuts off whenever I release the brake pedal.

When crawling forward, on releasing the brake, the AC compressor gets cut off. If I brake again, it switches on and on releasing the brake pedal, the compressor gets cut off again.

Same thing happens while reversing. When I release the brake, the AC compressor gets cut off and remains like that till I press the brake again.

Does anyone out there has a solution to this weird problem? What really could be causing this to happen?

[Flyer]

Originally Posted by Diesel lover

Does anyone out there has a solution to this weird problem? What really could be causing this to happen?

That's definitely weird! Does the AC work while idling, without brakes depressed? If so, then it might have something to do with engine rpms and not brakes.

[pkulkarni.2106]

I guess you should ask this in the Automotive air conditioning thread.


Is this behavior from the day one you purchased this car?
If so, I think this may be similar to my post here: https://www.team-bhp.com/forum/techn...ml#post4395874 (Automotive air conditioner servicing & maintenance)


As soon as you release your brake, engine gets loaded (both in forward and reverse gears). Because of that, the ECU might be cutting the AC off. At least this is the behavior in my case. Only difference is: mine is manual transmission. So, for me it happens when I release the clutch while starting off.

[Diesel lover]

Originally Posted by Flyer

That's definitely weird! Does the AC work while idling, without brakes depressed? If so, then it might have something to do with engine rpms and not brakes.

Yes, A/C works fine with brakes depressed in N or D or R gear. It's only when brake is released in D or R, the A/C cuts off.

Originally Posted by pkulkarni.2106

I guess you should ask this in the Automotive air conditioning thread.


Is this behavior from the day one you purchased this car?
If so, I think this may be similar to my post here: https://www.team-bhp.com/forum/techn...ml#post4395874 (Automotive air conditioner servicing & maintenance)


As soon as you release your brake, engine gets loaded (both in forward and reverse gears). Because of that, the ECU might be cutting the AC off. At least this is the behavior in my case. Only difference is: mine is manual transmission. So, for me it happens when I release the clutch while starting off.

I am not sure if it was from day 1 as the vehicle is primarily driven by my father. However ineffective cooling issue has been there since the very beginning.

[Rahul Bhalgat]

Have you confirmed with MASS?

If this behavior is by design and if MASS cannot re-program this officially, then it is better to leave it as it is.

One solution in the stop-go traffic is to keep the car at neutral (or P mode) between the crawls, to get some cool air.

[paragsachania]

We all would have come across this situation a lot many times during our everyday drive (In traffic) where the Brake Pedal sinks in a bit as you notice the compressor kicking in again.

At least in first few Gen Marutis, the Idle Speed would get bumped up by around 50 RPM as soon as the AC (compressor) kicked in to compensate for the load at low RPMs and as a cycle the RPM would reduce by 50 when the compressor shuts off. It is exactly here that the engine vacuum would slightly increase and hence a slip in the brake pedal.

As per your explanation, you say that the compressor cuts off as soon as you release the brake pedal. This is certainly not a normal behavior unless the ECU wants to cut off the compressor as you move fro standstill (Still weird).

However, to check if things are indeed normal, you may also want to try this in B2B traffic by keeping your leg pressed on the Brake pedal and you will mostly be able to notice the pedal sinking in as soon as the compressor cuts off.

[audioholic]

Does the AC work fine when the car is running normally in other gears?
If you repeatedly press and release the brake, does the compressor follow the same pattern?
If this issue happens only when crawling in D or R, it could be due to the fact that the engine speed is dropping lower than expected which makes the ECU cutoff the compressor to prevent a stall. Check the drop in idle speed when you release the brake. If it is falling below 700RPM, then there is an issue elsewhere which is just influencing the cutoff.
If there is no logic to this problem and the AC just follows the pattern of the brake application, then there will be some wiring issue.

[pkulkarni.2106]

Originally Posted by audioholic

it could be due to the fact that the engine speed is dropping lower than expected which makes the ECU cutoff the compressor to prevent a stall.

I guess this is the reason behind AC being cut off.
The car in question is an auto transmission. So, as soon as he releases the brake, the car starts to crawl. Hence, the engine RPM drops. So, probably, to avoid a stall the ECU may be cutting off the AC compressor.

[kat]

One of the links between the brake press/release and AC compressor ON/OFF is the vacuum brake booster. Mentioned below is the usual working of the vacuum brake booster and its possible link to the AC compressor.

- When the brake pedal is pressed, the brake booster gives mechanical advantage by releasing air from one side of the booster to the vacuum side thereby resulting in higher pressure in vacuum side of the booster. This phenomenon causes mechanical advantage and hence relatively lower pressure to be applied by the driver on the brakes.
- Now, this high pressure on the vacuum side needs to be released as soon as possible otherwise the brake pedal will be hard to press again.
- The vacuum side of the brake booster is usually directly connected to the air intake path. So, if there is a lower pressure in the air intake path, the high pressure which was developed on vacuum side due to previous braking will be released into the air intake path automatically due to pressure difference. Thus vacuum is restored in the vacuum side of the brake booster.
- In case the pressure difference between the vacuum side (high pressure due to brake press) and the air intake path is negligible, then the ECU automatically tries to reduce load on the engine which in turn can possibly close the throttle thereby resulting in lower pressure at air intake path, thus restoring vacuum at the vacuum side of the brake booster.
- One of the easiest action that the ECU can do is to "Turn off AC compressor temporarily" - reduces engine load and hence results in lower idling speed, thereby closing throttle relatively. And now, the vacuum is most probably restored on the vacuum side.
- Once vacuum is restored, the AC compressor is switched on again. This whole process takes place in a matter of hundreds of milliseconds (typically less than 1 second) so that the driver does not notice this.
- Pressure sensors at different places in brake booster and air intake path are used as feedback to ensure this works correct and fast.

In your mentioned scenario, I think that, when creeping is active in an AT, which basically works with the brake pedal press/release, this phenomenon occurs very frequently and might become all the more noticeable to the driver. So, I assume it is a normal behavior that you are noticing.

But I can be totally wrong if the mentioned scenario has never happened so far and it is happening from sometime in the recent past only.

[SS-Traveller]

Originally Posted by Diesel lover

It has a very strange behaving AC. When moving at crawling speed (when no accelerator input is needed) in stop go traffic (say in a traffic jam) or while reversing, the AC cuts off whenever I release the brake pedal.

When crawling forward, on releasing the brake, the AC compressor gets cut off. If I brake again, it switches on and on releasing the brake pedal, the compressor gets cut off again.

Very likely, your car is overheating marginally, especially with the AC on.

What you can do:

1. Wash the radiator and AC condenser with a water jet;
2. Have an AC technician check if the refrigerant level is fine;
3. Have him check if the cooling coil inside the cabin is fouled with dirt;
4. Check if the AC compressor drive belt is fine or slipping;
5. If the AC has not been serviced since the car was bought (or in the last 3 years), have the system completely serviced, including disassembling the dashboard & cleaning the cooling coil;
6. Replace the coolant if more than 4 years old, and wash out the innards of the radiator as well.

That will sort out your problem.

[Diesel lover]

Originally Posted by SS-Traveller

Very likely, your car is overheating marginally, especially with the AC on.

What you can do:

1. Wash the radiator and AC condenser with a water jet;
2. Have an AC technician check if the refrigerant level is fine;
3. Have him check if the cooling coil inside the cabin is fouled with dirt;
4. Check if the AC compressor drive belt is fine or slipping;
5. If the AC has not been serviced since the car was bought (or in the last 3 years), have the system completely serviced, including disassembling the dashboard & cleaning the cooling coil;
6. Replace the coolant if more than 4 years old, and wash out the innards of the radiator as well.

That will sort out your problem.

This happens every time, even during first cold start in the morning while reversing the car out from the garage till the main gate of our house (a distance of about 10 to 12 meters.)

Originally Posted by Rahul Bhalgat

Have you confirmed with MASS?

If this behavior is by design and if MASS cannot re-program this officially, then it is better to leave it as it is.

One solution in the stop-go traffic is to keep the car at neutral (or P mode) between the crawls, to get some cool air.

MASS is working on it as I had reported this to them. They say this should not happen as the cars currently being sold with the same automatic gearbox (discontinued ciaz 1.4 which are still unsold at dealerships and current 1.5 L ciaz) do not show similar characteristics.

Originally Posted by paragsachania

We all would have come across this situation a lot many times during our everyday drive (In traffic) where the Brake Pedal sinks in a bit as you notice the compressor kicking in again.

At least in first few Gen Marutis, the Idle Speed would get bumped up by around 50 RPM as soon as the AC (compressor) kicked in to compensate for the load at low RPMs and as a cycle the RPM would reduce by 50 when the compressor shuts off. It is exactly here that the engine vacuum would slightly increase and hence a slip in the brake pedal.

As per your explanation, you say that the compressor cuts off as soon as you release the brake pedal. This is certainly not a normal behavior unless the ECU wants to cut off the compressor as you move fro standstill (Still weird).

However, to check if things are indeed normal, you may also want to try this in B2B traffic by keeping your leg pressed on the Brake pedal and you will mostly be able to notice the pedal sinking in as soon as the compressor cuts off.

When in B2B traffic with gear in D mode and brake pedal pressed, the A/C does not cut off. It only cuts off when cabin temp drops considerably. It is when brake pedal is released to make the car move, the A/C cuts off and starts again after 1 or 2 seconds. If I brake again, the A/C remains on and on releasing the brake again to get a move, the compressor cuts off again.

Originally Posted by audioholic

Does the AC work fine when the car is running normally in other gears?
If you repeatedly press and release the brake, does the compressor follow the same pattern?
If this issue happens only when crawling in D or R, it could be due to the fact that the engine speed is dropping lower than expected which makes the ECU cutoff the compressor to prevent a stall. Check the drop in idle speed when you release the brake. If it is falling below 700RPM, then there is an issue elsewhere which is just influencing the cutoff.
If there is no logic to this problem and the AC just follows the pattern of the brake application, then there will be some wiring issue.

At cruising speed, it cannot be judged if the compressor is cutting off when brake is pressed as on and off clicks of the compressor aren't that audible. Maybe it would be happening at that point too.

Originally Posted by pkulkarni.2106

I guess this is the reason behind AC being cut off.
The car in question is an auto transmission. So, as soon as he releases the brake, the car starts to crawl. Hence, the engine RPM drops. So, probably, to avoid a stall the ECU may be cutting off the AC compressor.

Had this been the case, this should have been happening in other maruti automatics as well (like in ciaz or AMT vehicles). I own a Celeiro AMT and it never cuts off A/C like it does in dzire.

[Jaggu]

Originally Posted by Diesel lover

Hello members!

I own a 2012 Dzire with a 1197 cc K series petrol engine mated to a 4 speed torque convertor automatic transmission.
===
Does anyone out there has a solution to this weird problem? What really could be causing this to happen?

Let me see if I get it right, every time you take the legs of the brake pedal, to crawl, the AC compressor cuts off? Forward and reverse. Then it switches back on and continues to work normally?

I have driven similar car and never noticed such a behaviour. So it is definitely not normal. AC compressor cuts off only when the temperature has fallen to cut off levels OR under sudden acceleration.

Ask your dealer to check 1- the accelerator pedal ac cut off switch, it is a small switch that sits under the dash linked to the accelerator pedal, this activates when you fully press the pedal. If it is shorted, could be the cause. 2- check the wiring circuit for that and brake lights, for any mess up.

Curious to know if this is a recent phenomenon or has always been there?

[audioholic]

Originally Posted by Diesel lover

When in B2B traffic with gear in D mode and brake pedal pressed, the A/C does not cut off. It only cuts off when cabin temp drops considerably. It is when brake pedal is released to make the car move, the A/C cuts off and starts again after 1 or 2 seconds. If I brake again, the A/C remains on and on releasing the brake again to get a move, the compressor cuts off again.

This looks like excessive drop in idle RPM to me, hence the ECU cuts off AC compressor. Ask the dealership to check if the torque convertor is working fine, since it should not ideally cause a drop in the engine speed when the car is crawling. In the AMT, its a different mechanism at play. The ECU voluntarily increases engine speed to more than 1000 RPM when it starts releasing the clutch. In the Dzire automatic, there is no such thing done since the gearbox is mostly mechanical.

Originally Posted by Jaggu

Ask your dealer to check 1- the accelerator pedal ac cut off switch, it is a small switch that sits under the dash linked to the accelerator pedal, this activates when you fully press the pedal. If it is shorted, could be the cause.

Jaggu, there is no such switch in the car. Some automatics have kickdown switches in this way, especially those who have mechanical throttle. But the Dzire does not have one in the automatic to shut off AC. ECU controls it based on the accelerator position since its anyway electronic.

[Diesel lover]

Originally Posted by Jaggu

Let me see if I get it right, every time you take the legs of the brake pedal, to crawl, the AC compressor cuts off? Forward and reverse. Then it switches back on and continues to work normally?

I have driven similar car and never noticed such a behaviour. So it is definitely not normal. AC compressor cuts off only when the temperature has fallen to cut off levels OR under sudden acceleration.

Ask your dealer to check 1- the accelerator pedal ac cut off switch, it is a small switch that sits under the dash linked to the accelerator pedal, this activates when you fully press the pedal. If it is shorted, could be the cause. 2- check the wiring circuit for that and brake lights, for any mess up.

Curious to know if this is a recent phenomenon or has always been there?

Hi there,

Glad to find someone who has driven the exact same vehicle as the one I own.

To be double sure is it the one - https://www.team-bhp.com/forum/test-...ml#post2666021 (Review: The 2nd-gen Maruti Dzire)

To check closely the cut on and cut off of the compressor when releasing brake pedal in D or R, you need someone at the wheel and another guy with the bonnet open looking towards the compressor.

Do you know someone who owns a similar vehicle? If yes, I would be glad to talk to him on phone and take some inputs.

Also MASS guys visited my place yesterday and they said that for this particular 1.2 L engine with torque convertor automatic, this cut on and cut off is normal as this is hard corded in the ECU. Since 1.2 is a tiny engine and torque convertor needs a lot of initial torque so it cuts of compressor when moving forward. He however said that this should not happen while reversing.

I told him that this does not happen in 1.4 ciaz or 1.5 ciaz. He said that these are bigger engines with more torque available on tap.

I insisted that he should still write internally to someone so that they develop some solution to this (maybe ECU flash with some updated firmware). He replied he will do it. I am not too sure about this though.

Since these similar variants weren't sold in large numbers, so finding one is a tough job as this vehicle is now discontinued.

[Jaggu]

Originally Posted by Diesel lover

To be double sure is it the one - https://www.team-bhp.com/forum/test-...ml#post2666021 (Review: The 2nd-gen Maruti Dzire)

Yes this is the same model my friend had, unfortunately she has now sold it. So no way to go back and refer. Ask dealer to run scan and update the software to latest and see if it helps.