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-   -   Why Santro Xing AC not effective at low speed ? (https://www.team-bhp.com/forum/technical-stuff/104122-why-santro-xing-ac-not-effective-low-speed.html)

I have been facing this issue since I bought my Santro 4 years ago. Its AC works fine when I am at a speed above 30 KMPH but once I am stuck in Jam or an bumper to bumper traffic its AC's performance is pathetic. Even though the compressor is running but no cool air. Sometime I get so frustrated that I stop the AC and open the window glasses to breath fresh air.

There is no issue at all with AC when car is running above 20-30 + KMPH.

Can any one suggest how this issue can be rectified ?

This is a common issue among all santros. I believe the compressor is small and at lower RPM's does not generate enough cooling. The issue is somewhat gone when the engine RPM increases. Not sure if there is any fix to it. If not doing already, maximize the use of internal air circulation option. You can still get the ac cooling checked to ensure it's working as normal. I am saying the above based on my experience with 2 santros we have/ had in the immediate family.

I suspect that the heat exchanger is more efficient at speeds above 30 kmph due to increased ram air cooling. As the speed increase more air passess over the heat exchanger and takes greater amount of heat away. This is noticeable in Santro, but is true for many cars.

One option that should work well is to install good quality - premium - solar film on the windows, including the front win-shield. Arctic series from Blaupunkt or V70 from vKool should do the trick. You need to carefully look at heat blocking film that you choose.

This should reduce the heat build up inside the car, and therefore tip the balance in favour of cooling.

This is because at low speeds the AC condenser is not getting enough air to cool the hot refrigerant, and hence the systems efficiency in cooling the cabin air goes down. Where as, at speeds, the the ram air is sufficient to cool the condenser.

Regarding a solution to the problem, 1st you have to check if all santros have this issue. If not, get your AC serviced, and gas refilled. If yes, then you might have to install an additional fan or go for a bigger compressor. However, I'm not sure how practical the 2nd suggestion is.

Make sure the radiator fins are not choked with foreign materials like tree leaves, debris etcetera. A/C does not perform effectively at low speeds as the hot air needs to escape the system quickly and this is not possible at idling or low speeds. But it doesn’t mean that the A/C will not cool. Get your A/C checked from independent A/C workshop.


I don't think that it is possible to go for a bigger compressor. This will require changing of other components and will overheat the engine.

How is the engine temp. usually? Do you find the temp. guage needle in the middle often? If that is the case, check if there's enough coolant.

Also being from Delhi, assuming that you've used the a/c quite a bit, do get the refrigerant level checked and a/c filter cleaned.

This is common to all santros, you should just switch off the fan once and then switch it on. The compressor turns off at low speeds to reduce load on the engine to enhance pick-up.

I noticed this mechanism a few years back in bumper to bumper traffic.

+1.

I just came back from a 300km trip in a Santro Xing, and it had the exact same issue. Ineffective AC at low speeds.

I guess one will have to live with it.

+2

I remember the driver doing the same thing(switching off the fan and switching on) on a 1999 Santro when we were on a trip to Dahej.

But the logic of cutting of a compressor at low speeds seems weird ; on the old cars like Fiats,the ac would cut off when you pressed the accelerator more

I own an 8-year old Santro Xing that I drive only within city-limits. I do switch on the AC occasionally, and I have noticed that the AC is not quite as effective at low speeds. Although it isn't really a cause for concern, do get a thorough diagnosis of the entire AC and all its components.

I do find myself switching on the AC at traffic-lights, and I have noticed that the performance of the AC improves once the car picks up speed. However, it isn't a huge difference, and does a decent job at lower speed.

Perhaps, there could be an issue with the condenser. Do check the coil as well, if there is any damage to it, as I've heard that it might need replacement after some time. I've never been asked to change it, the service personnel haven't suggested I do, so I'm guessing it's alright.

If you aren't happy with the AC's performance even after a check-up and correction, do take it to another service-center and compare notes.

Also, I suggest you don't switch on the AC immediately. Wait for the car to warm up a bit, and after a 10-15 minute drive, switch on the AC. It should be alright. :)

EDIT: Santros have great ACs, actually. They're very effective and quick to cool. It's only the initial hiccup that is noted.

Never seen this problem in Automatic Santro that I owned for 7.5 years. May be this is common to only manual Santro.

This occurs in all cars. In smaller cars it is more apparent due to their smaller engines, compressors, heat exchangers, etc. It happens in the Bolero too, even though it possibly has the best aircon ever fitted to a car this side of 10 lacs. Also, if you do not use sunfilm (I don't) then your AC will struggle even more when the car is not moving.

I don't think it has anything to do with it being a small car.

The only effect the AC will have on the car is the sap in power. The AC will consume some of the power the car makes, making it even more sluggish. But the AC should work normally. Only the car would feel slower once the AC is switched on. :)

True but on the first part I beg to differ. This is not true for Alto even with the 800 cc engine. It cools well even in idle, at signals, and the real problem is the lack of power of the engine to move swiftly once the signal clears.

Same here. Even if I let Alto idle for 1 hour with A/C, the cooling is not compromised.

In Santro, the fan is not powerful enough to throw the hot air out of the condenser coil. Either this or the condenser fins are a bad design that don't have good air flow.