Can you make a climate control system

[tsk1979]

On the Verna thread many people have said that a climate control system should be given.
Same on VXi vs LXi debate in case of Baleno.
And why not, using the best parts, it would cost not more than couple of thousand rupees.

We have lots of installer and modders here who have the knowhow of installing AC systems, headers, engine ECU remaps, NOS kits etc., etc.,

This will make an interesting project.
The theory is very simple.

All you need is a dual temparature control switch. If temparature falls below 0.5 degrees of the set temparature, activate heater and if it goes 0.5 degree above the set, activate AC.
At set temparature, switch off both.
So in summers you will see AC activating occasionally.
In winters you will see Heater working.

On the practical front, you will need to disconnect the AC and heater switches and replace them with this dual switch.

If need not be electronic, you can have a caliberated dial sitting somewhere hidden.
the cost should not be more than few hundred rupees in this case.

Anybody here done this? Is this really a big deal? DIY guys why not make a prototype. If your cars are not in warranty, this wont harm at all.

[a4_attitude]

very intresting,,,, any volunteers?

[Su-47]

Originally Posted by tsk1979

The theory is very simple.

All you need is a dual temparature control switch. If temparature falls below 0.5 degrees of the set temparature, activate heater and if it goes 0.5 degree above the set, activate AC.

At set temparature, switch off both.
So in summers you will see AC activating occasionally.
In winters you will see Heater working.

Practical problem: Where to place the temperature sensors? If you put it on the grill, the grill temperature is way below the cabin temperature when the AC is running.

Does anyone know where the sensors are in Swift Zxi or Baleno Vxi? If they are on the grill, then what is the correlation function used between grill and cabin temperature ?

Cheers,
Su-47

[tsk1979]

Originally Posted by Su-47

Practical problem: Where to place the temperature sensors? If you put it on the grill, the grill temperature is way below the cabin temperature when the AC is running.

Not so tough, put it in the space above the seat belt and take the wiring from within the frame.
Or it can be near the seat adjustment controls, or in the headrest, but then wiring will show.

Does anyone know where the sensors are in Swift Zxi or Baleno Vxi? If they are on the grill, then what is the correlation function used between grill and cabin temperature ?

Definately not on the grill. Must be someplace else.

[a4_attitude]

we are talking about sensors are they easily avialable?? it will be a nice idea though converting my swift vxi to zxi...
and about the location in swift its not on grill its below the HU space
Keep goin..
W.A

[Insane Devil]

A Nice topic! i was considering getting it done by getting parts from abroad for my Tucson, if its possible to carry out the operation.

Theoratically it sounds clean and simple. But i wonder what practical problems might come.

@ a4_Attitude: Sensors will not be a problem, u can buy it off teh shelf from Maruti Workshops, just need to trace the right part/part no. in the sparepart catalouge of the Swift.

[adya33]

Originally Posted by a4_attitude

we are talking about sensors are they easily avialable?? it will be a nice idea though converting my swift vxi to zxi...

As Insane Devil said you can buy sensor from Maruti or alternatively use transducer. Which is again easily available.

All you need is a dual temparature control switch. If temparature falls below 0.5 degrees of the set temparature, activate heater and if it goes 0.5 degree above the set, activate AC.

One problem though, you might occasionally have heater going ON for no reason, thus reducing your cooling. The tolerance levels should be increased up to 2 deg C.
Also the problem with sensor placement is that it should be within cabin but at the same time should have some sort of mechanical protection.
Swift has sensor in its dashboard. That seems to be nice place.
But is one sensor sufficient? I remember having debate sometime ago about Maruti using only 1 sensor in Swift as opposed to 6 sold in Europe.
In my opinion having 2 to 3 sensors will mean better all around cooling. But it will also mean complicating things.

[vikram_d]

Well on the swift there are two sensors. One is in front of the windshield Over on the drivers side and the other is right next to the steering wheel just below the wiper switch. Both inside the cabin.

[Mpower]

Originally Posted by tsk1979

And why not, using the best parts, it would cost not more than couple of thousand rupees.

I think you may be off by a couple of zeros. (at least one). ATC unit is a closed loop control system with its own ECU and several sensors and actuators. You need solenoids and motors to adjust the air mix and and increase and decrease fan speeds. Dual Zone ATC doubles the complexity.

[tsk1979]

Originally Posted by Mpower

I think you may be off by a couple of zeros. (at least one). ATC unit is a closed loop control system with its own ECU and several sensors and actuators. You need solenoids and motors to adjust the air mix and and increase and decrease fan speeds. Dual Zone ATC doubles the complexity.

I was looking for a more simplist system where fan speed is user controlled and this just controls the heater and AC, like what happens in home window AC systems.

One group in our college made such a system(just the switch part) and the cost was < 500rs.
One sensor mounted near handbrake or near the steering, thats all.
Already most cars have a cutoff switch which turns of AC when it gets cold. So you need a dual switch sensor which is not costly.

If you want to go simplistic way you can use two different switches too!

[DRC]

It really sounds very simple, but in practice it does take some sizable effort, if not impossible.

To control the AC, with changing load conditions like driving in sun and maintaining say 22 deg, and driving in cold conditions and maitaining the same temperature, and again, imagine a moving car through different ambient temperatures.... it soon becomes very complex an algorithm, and requires something called PID controller (Proportional, Integral, Differential controller). All temp controllers do have this as a module. A very simplistic form of this is implemented only for temperature (not the fan speed) using a bimetal thermal strip in lower end cars (same thing works in controlling the fan in the engine cooling system), This is actually a P controller only with hysterisis is built in by the charecteristics of the the bi-metal strip. but an electronic implementation is quite complex.

My 2 cents

[tsk1979]

Originally Posted by DRC

It really sounds very simple, but in practice it does take some sizable effort, if not impossible.

To control the AC, with changing load conditions like driving in sun and maintaining say 22 deg, and driving in cold conditions and maitaining the same temperature, and again, imagine a moving car through different ambient temperatures.... it soon becomes very complex an algorithm, and requires something called PID controller (Proportional, Integral, Differential controller). All temp controllers do have this as a module. A very simplistic form of this is implemented only for temperature (not the fan speed) using a bimetal thermal strip in lower end cars (same thing works in controlling the fan in the engine cooling system), This is actually a P controller only with hysterisis is built in by the charecteristics of the the bi-metal strip. but an electronic implementation is quite complex.

My 2 cents

Sometimes the simplest system is the best, no need of going to mumbo jumbo. I have seen such a switch working, and given few minutes in SJP road market and 2 hours with a circuit board and solder I can make one.

Picture this.
Temparature set to 22 degree.
If temp > 22.5 degrees Swtich on AC
If temp < 21.5 degrees Switch on heater.

How complicated can that be. The switch is easy, very very easy. A simile google search will find you countless circuit diagrams all assemblable by anyone who has spent a semester in any electrical/electroncs lab.

Its the connection part to AC and heater where the modders will come in.

To convince you further, lets take a simple electronic thermometer people keep inside cars
The sensor reads temparature and then displays it on a LCD. It means that it is giving some current to various points on LCD input screen to generate that display, or it can be thermistor which varies resistance based on temparature etc.,
That same sensor can be used for this purpose.

And before you start counting money, the thermometer with dual display and two sensors costs only 300rs.
Go figure.

Now lets come to a complicated microprocessor linked climate control.
All you need is a CPU with some memory to load the program. A CPU with 80386 equivalent computing power is sufficient, and with the board will cost around 2-3000rs.
Thats for you and me. For a company a very nice complicated system cannot cost more than 3-4000rs.

PS: many electronic gadgets you pick up for 20,000rs in the store in India or about 300 US$ cost just 30$ to build(including factoring the cost for designers salaries etc., and leaving out capitol costs of fab etc.,).

[DRC]

TSK, All the best for the project...

IMHO, you do not even need a x386 processor to implement the complex PID controller I mentioned. All you need is a simple 89c52, which is readily available in SP road for Rs35.00 only. May be you need to add a ADC to measure tempt and make decisions in the micro processor.

As you mentioned , yes the switch is very very easy. like a thermostat. this works perfectly alright for a watetr heater, where the required tempt is always higher than the ambient say 60 deg. and you decide to whether heat it further or not. Trust me, I have worked on such issue, both for fun and at work, they do get complex. Add controlling the fan speed , you may go crazy!

[tsk1979]

No matter how complex you go DRC, do you actually believe that the cost of the system will go more than 5000rs for the manufacturer even in case of a multi sensor system. Its another one of those cases of percieved value addition.
What shocks me that though we have modders who can do such wizadry with the engine/ECU which would put an automobile engineer to shame, none of the modders I met have directed their energies towards such a system.
Is there no market.
I for one would love to spend 3000-4000rs and get a climate control system for my car!

[DRC]

And you know what, the human brain does this task with amazing ease. Hence we may not be able to quickly quantify the complexity involved in it...

OT
For an anology, take the example of cruise control, all you have to do to maintaine a given speed is press the gas if the speed is less and not press the gas/break if it is more. This looks so damn easy!

See how cruise control works http://auto.howstuffworks.com/cruise....htm/printable