[wanderernomad]

I know this is stupid or fruitless but I have been bitten by this bug to have a couple of rear vents for the circulation of air to the rear seats. The options I have been given by a few mechanics are :
1. Installing a roof mounted blower
2. Moddifying the AC circulation system from the engine bay itself (ruled out due to cost and other factors).

I am thinking of either trying to source a single small blower to install beneath the center arm rest between the two front seats or making a plastic/wooden enclosure to house the rear AC vents and fix it to the mounting of the central arm rest. I plan to get two straight AC pipings and attach them to the vents on one side and somehow use a rubber tubing kinda thing to connect them to the air vents in the footwells. The blower in the marina is good and I think at speed 3 and upwards the flow of air to these rear vents would be just about ok.

I plan to use insulating foam and alluminium foil to wrap inside the plastic/wooden enclosure of the rear vents.

Any suggestions on either improving the above set up or a complete new idea on how to do it is not only most welcome but is also urgently needed.

Cmon guys please guide me through this.

[Akshay1234]

find out how tata does in it in the indigo xl. then you could probably do it the same way.

[wanderernomad]

Indigo XL has a separate blower unit and the entire setup is modded from the engine bay itself. The only thing that can be used from the XL is probable the rear console thats all.

[greatmana2000]

You will have to change the evaporator coil to increase the performance of the air conditioner . There is no way out

[wanderernomad]

@great : But what I am looking for is merely circulating air to the rear seats. Do I have to change the coil for it as well?

[wanderernomad]

After a lot of procastinations I have finally decieded to add the rear seat aircon vents for the sole purpose of air circulation. The basic idea is to have the air circulated to the rear seat passengers from in between the front seats.
The basic layout is to take two pipes from the front floor vents along the central console to the rear and add vents for air dispensation. The modus operandi is to force blow the air into those pipes at the front floor vents and then once again force flow the air out of the vents at the rear.
Items being used are as follows:-
1. Two 2.5 feet long, 5/8 diameter copper pipes. (The kind used in split ACs)
2. Two 12V CPU cooler fans up front to force feed the air into the collecting funnel.
3. Two 12V CPU cooler fans at the rear to force blow the air through the vents.
4. Two AC vents plastioc types.
5. Tin sheet to make a collection funnel up front and a rear collection chamber.
6. Glass cotton for insulation.
7. Alluminium foil to cover glass wool and inner lining of the funnel and the rear collection chamber.

What i propose to do is as follows:-
1. Fix the two 12V fans inside the plastic casing of the front floor vents. There is an enormous space up there and its hollow from inside where these fans fit quite nicely. (Now how do I power them? Options are i) I take power out from the 12V socket either through the long pin of a mobile charger where the output is coupled with the fans input; or ii) I use a socket where in the power is drawn from the wires feeding the 12 V charging point. Is it ok to run 4 fans from 2 sockets that all draw their power from the input of the charger? Or do I run a cable from the battery and power all 4 fans separately?
2. Make a funnel out of the tin sheet or use a normal plastic funnel available in the market and fix it with screws to the oputside of the blower casing so that the fan blows directly into the funnel's mouth. Insulate it with glass cotton and foil.Repaet the procedure for the other side.
3. Attach the two pipes and run them along the entire length of the central console along the gear lever and hand brake. Insulate the pipes.
4. Make an insulated collection chamber where in both the pipes terminate.
5. Attach the remaining two 12V cpu fans and direct the air flow towards the vents attached to the other end of the collection chamber.
6. Add a switch to turn the fans on & off as per requirement.

Guys need advise and suggestions on this. Where do you see the possiblities of things going wrong and where do you foresee difficulties in getting this thing done.

[prabhuav]

nomad,

there are two options for the wiring that I can think of:

1) If you are looking for the fans to come on when you switch the main blower on,I would suggest that you take a lead from either the blower switch or the the blower itself. I belief that supply should have enough juice to run the 2 fans

2) If you want a separate switch to run the blowers, you can run the leads directly from the battery. I would avoid the lighter socket as the fuse rating might not be enough to run both the fans.

Quick sidebar questions:

1)what are the copper pipes for?

2) Why are you bothering so much about the insulation? you r ducts are going to be inside the cabin. Heat losses(or gain ) will be insignificant as the the air around the duct will be cooled be the front vents anyway.

[wanderernomad]

@prabhu : the copper pipes are for channelling the air from the front fans to the rear vents. The insulation is more for plugging the air leakages from the joints and preventing the pipes from bumps etc.
Thanks for the gr8 idea of running the fans from the blower and through its switch. It makes sense.

[rkbharat]

wanderernomad, I suggest you look for some better options like Roof AC or something similar to what we have in Indigo XL.

I think roof top AC can be fitted and will be much better than this DIY. Should cost you around 12K-15K.

[prabhuav]

Rajiv,

An additional ac will increase the load on the engine. Nomad is primarily looking for improved circulation .

Nomad:

5/8 " copper pipe is used in the split A/C to move the refrigerant gas across . THis is a high pressure low volume situation. Moreover 5/8 copper is a pain in the a$$ to work with unless you have a pipe bender and the cross section is too small to move any amount of air.

All you need is a 3" flexible PVC pipe , as this is exactly what the ac guys use. you can always use a silicone sealant between this and the funnel.

Additionally you might want to think of a different fan as the cpu fans are high speed small area fans. I dont think the motors have enough torque to move any amount of air. Why dont you try to get the blower fan from an 800. That should so the job good enough.

As a matter of fact you can think of getting console and piping off a scorpio. The scorpio has the central blower for the back, albeit passive. you can use the additional blower to suck the air from under the dash and push it to the back.. Remember suction is always tougher than blowing

[wanderernomad]

I have kept these options open. Ill be going to the markets this weekend to check out the stuff and the prices.
@RK : I had these options but then they would take the fun out of DIY. I want to do something with my hands and feel good about it when it works..lol. If it doesnt at least I have tried and moreover am in no mood to spend 12K on I want to make for my whims. (wife would kill me if i did)
@Prabhu: I have the pipe bender and other things at my office workshop. A 3" PVC pipe is definately an option I am considering. Do you ahve any idea how the passive back blower of a scorpio works? I think it intakes from the engine bay but Ill go and check out at the market this weekend.
Also when you say a blower fan from 800, what exactly do you mean?

[phamilyman]

Have you tried the Indigo XL setup? like scorpio it is.

[prabhuav]

@phamilyman,
I thought that the XL had a roof blower and not a central console one.. my bad

@Nomad, I meant the blower fan from a maruti 800. My assumption is that it will draw the least amount of power and will be inexpensive.

call me on 9845268678. I am thinking of something like this for my padmini too

[rkbharat]

Ok if that is the case, then I will have to search my old office Sumo cab, which has exactly what you are thinking of. It had blowers between front seats and taking cooling from existing AC. And it was very effective.

Originally Posted by wanderernomad

@RK : I had these options but then they would take the fun out of DIY. I want to do something with my hands and feel good about it when it works..lol. If it doesnt at least I have tried and moreover am in no mood to spend 12K on I want to make for my whims. (wife would kill me if i did)

[wanderernomad]

@RK Chief what did you find fromt hat SUMO?
Anyway meanwhile i found that as said earlier the fans were no good.They just dont move any air. So today Ill try and substitute them with the AC supply fans from the CPU. The set up as of now is as follows:-
1. Two 1.25 mtr white flexible pvc pipes to carry air from the front vents to the rear. (the pipes are the kind we use as drain pipes in sinks washbasins etc.)
2. The pipes have been screwed onto the 2 ltr COKE bottles heads after removing the caps.
3. The bottles ahve been cut at the neck to form a funnel which has been pushed into the floor vent space so that the vents direct air into the inverted bottles and onto the pipes.
4. The CPU fans have been fixed two up front and two at the rear (though will remove them now) after taking the power from the wiper switch and earthing the other end to the floor. The on/off switch is a push pull type and installed in an already existing small hole inside the small parcel shelf beneath the steering wheel of the marina.
The bottles were used instead of the regular funnels as I found pushing the bottle frame into the vent space easier then pushing the funnel into them.
The air is coming around to the back even at lower blower speeds but now Ill try and see if the AC supply fan is able to circulate some air or not.
Am also going to the markets after lunch today to hunt for the ac vents. Alt the Indigo XL rear setup or the scorpio rear set up if can be found at a reasonable price.