[karthik123]

I haven't been following this thread a lot lately but i would like to inform you guys that even with the dual-fan set up for the condensor the problem is not entirely solved , when it gets really hot outside.. that's when the AC gives up , it seems to be over loading the engine way too much, so i guess we have to live with it and hope the summer passes away :P

[headers]

Originally Posted by humyum

When you add load to an engine at idle rpm like the Air conditioner, the idle rpm has to increase come what may to compensate for the increase power consumption by the AC fan (2 fans in case of the Thar), increased heat generation so more water circulation is needed by the water pump to the water jackets and to compensate for the extra load put on the engine as without the increase in RPM it will cause a vibration filled idle because of the load...

Not necessary at all sir. A fan or 2 hardly draws much current - The extra load on the engine when calculated as a % of total power of engine helps decide whether the idle needs to be increased or not!!

3 liter and 4 liter diesel trucks have this increase idle rpm function and so should the THAR.

Again - Not necessary just because a 3 or 4 litre does it does not mean the THAR should do it!!!

Originally Posted by karthik123

I haven't been following this thread a lot lately but i would like to inform you guys that even with the dual-fan set up for the condensor the problem is not entirely solved , when it gets really hot outside.. that's when the AC gives up , it seems to be over loading the engine way too much, so i guess we have to live with it and hope the summer passes away :P

What exactly happens ? - Not enough cooling or does the fan appear to slow down in speed?

It could be a AC setup issue too - Check the AC thermostat setting!

[humyum]

Originally Posted by headers

Not necessary at all sir. A fan or 2 hardly draws much current - The extra load on the engine when calculated as a % of total power of engine helps decide whether the idle needs to be increased or not!!



Again - Not necessary just because a 3 or 4 litre does it does not mean the THAR should do it!!!

The idling rpm increment of an engine is calculated by any company keeping all the power consuming devices on at the same time and then deciding the idle rpm increment factor, but there is ALWAYS an increase no matter what with an AC in question. In case of the Thar, 2 Condensor cooling fans, one blower, Headlights, Stereo ( Everyone fits one), Secondly the AC Compressor of 150 cc that is fixed in Thar should be drawing in a cool 8 bhp + for it to keep running.

So along with all these parameters like headlight, Blower, fan, stereo putting a load on the alternator + AC compressor pulling in 8 bhp arounds of power, it would unfair to assume that rpm increment is not necessary. Cars like Land Rovers which are double the power and bhp need an idle increase than what is a Thar ? It will just stall more easily in traffic conditions minus any idle rpm increase.

Just because a 3 and 4 litre diesel engine does it proves my point even more clearer than the Thar should have this function and it does not because the AC in it has no connection wit the ECU, and hence its not an 'AC' ready car by miles.

I am not taking away anyone's effort here in making the THAR, but when it comes to facts and figures please don't shy away from it and call it an AC ready car just because it has some provisions for pipe insertions and pully arrangements. In today's era, the ECU has to talk to the AC. PERIOD and when that happens, everyone can call the THAR an AC ready vehicle. Till then NOT !

[headers]

Originally Posted by humyum

The idling rpm increment of an engine is calculated by any company keeping all the power consuming devices on at the same time and then deciding the idle rpm increment factor,

Agreed!

Originally Posted by humyum

but there is ALWAYS an increase no matter what with an AC in question. ..

Not necessary - Not all cars have an increase in idle RPM!!!

Originally Posted by humyum

Just because a 3 and 4 litre diesel engine does it proves my point even more clearer than the Thar should have this function and it does not because the AC in it has no connection wit the ECU, and hence its not an 'AC' ready car by miles.

Bigger is not always better

Originally Posted by humyum

I am not taking away anyone's effort here in making the THAR, but when it comes to facts and figures please don't shy away from it and call it an AC ready car just because it has some provisions for pipe insertions and pully arrangements. In today's era, the ECU has to talk to the AC. PERIOD and when that happens, everyone can call the THAR an AC ready vehicle. Till then NOT !

How are you sure that the ECU is not talking to the engine - Just because there is no increase in idle RPM?

[csateesh]

Originally Posted by humyum

... but there is ALWAYS an increase no matter what with an AC in question.

Originally Posted by headers

Agreed!
Not necessary - Not all cars have an increase in idle RPM!!!

@humyum - Petrol engines handle the requirement for increased current differently compared to diesel engines. Petrol engines need an increase in power and hence the increase in idling.

Diesel engines handle it by increasing torque which is accomplished in advancing timing and hence you don't see an increase in idling speed.

@headers - You are right - Not all cars need an increase in idling speed

Regards

Sateesh

[Jaggu]

So much of discussion still no resolution for the actual problem, just like any Thar thread. M&M please help the poor friend of karthik123

[Blue Thunder]

Originally Posted by humyum

....the idle rpm has to increase come what may to ....

Not necessarily, humyum ; if the engine has good low-end torque, and the idle rpm matches the minimum rpm requirements of the A/C compressor, the idle rpm doesn't need to increase when A/C is switched on. IIRC, the Armada Grand had an excellent A/C, and you could never make out when the A/C was coming on/going off. The idle RPM of the 2.5L IDI could handle that....guess the CRDe in the Thar should also be able to handle it.

Originally Posted by humyum

....the idle rpm has to increase come what may to compensate for the increase power consumption by the AC fan (2 fans in case of the Thar), ....

Originally Posted by humyum

....3 liter and 4 liter diesel trucks have this increase idle rpm function ...

any specific examples in mind?

Originally Posted by humyum

.... and call it an AC ready car just because it has some provisions for pipe insertions and pully arrangements. In today's era, the ECU has to talk to the AC. PERIOD and when that happens, everyone can call the THAR an AC ready vehicle. Till then NOT !

The mechanical provisions being in place is what makes a vehicle be called AC-ready , in that sense, the Thar is definitely AC-ready. Engine ECU being able to talk to A/C is not a critical factor...a good thermostat to control the fan should be sufficient for effective functioning of the A/C, given the excellent low-end torque of the Thar CDRe engine.

[droolingvoyager]

So here comes a blocker I guess. Already booked a thar, however the M&M dealer and workshop @ bangalore (India garage) are asking me to get the AC fitting done from outside. I earlier thought this would be OK, but after reading this thread, is certainly a deal breaker. I do not want a vehicle which I am gonna use for me and my family to have a AC without heater or an AC which fails when its HOT.

I was surprised the dealer and service center both saying they do not have technical knowledge to do this on thar yet.

[Jaggu]

Originally Posted by droolingvoyager

So here comes a blocker I guess. Already booked a thar, however the M&M dealer and workshop @ bangalore (India garage) are asking me to get the AC fitting done from outside. I earlier thought this would be OK, but after reading this thread, is certainly a deal breaker. I do not want a vehicle which I am gonna use for me and my family to have a AC without heater or an AC which fails when its HOT.

I was surprised the dealer and service center both saying they do not have technical knowledge to do this on thar yet.

Unlike what is being portrayed in this Thread. There are many competent specialist in BLR who can do a good job with AC installation, be it Thar or not. I feel it would be much cheaper also.

[humyum]

Originally Posted by Blue Thunder

Not necessarily, humyum ; if the engine has good low-end torque, and the idle rpm matches the minimum rpm requirements of the A/C compressor, the idle rpm doesn't need to increase when A/C is switched on. IIRC, the Armada Grand had an excellent A/C, and you could never make out when the A/C was coming on/going off. The idle RPM of the 2.5L IDI could handle that....guess the CRDe in the Thar should also be able to handle it.








any specific examples in mind?





The mechanical provisions being in place is what makes a vehicle be called AC-ready , in that sense, the Thar is definitely AC-ready. Engine ECU being able to talk to A/C is not a critical factor...a good thermostat to control the fan should be sufficient for effective functioning of the A/C, given the excellent low-end torque of the Thar CDRe engine.

How did i miss this for so many days anyway, Yes as a matter of fact I do have specific examples in mind, Firstly its a BMW 320 D, 177 Bhp with 380 nm torque, idle goes up with the AC.

A Mercedes E 320 with 220 bhp and V6 Diesel, Idle goes up by a notch with AC.

Ford Smax 2 Liter Diesel with 140 bhp, Idle goes up with AC.

Have a Swift Diesel and although its rated at 76 bhp and 19 kgm torque the AC compressor size must be around 100 to 120 cc which is lesser than the Thar's so kind of negates the less power output and RPM goes up by 100 when the ac is switched on.

A car is AC ready, when every parameter is taken care by the company and not by dealers who in this case have no clue too.

Your 2.5 Armada had no provision for Idle Rpm increase as it was made in pre era's and secondly there was so much vibration, NVH already that it would not make a difference if added load is added and engine shook a bit more.

Cheers.

[tsk1979]

@humyum, in the Tata Safari 2.2, idle rpm does not change with AC on. So some vehicles have idle rpm increase, and some do not.
A system can be designed in any which way

[MileCruncher]

Originally Posted by humyum

Your 2.5 Armada had no provision for Idle Rpm increase as it was made in pre era's and secondly there was so much vibration, NVH already that it would not make a difference if added load is added and engine shook a bit more.

Not true. Any Diesel vehicle with a Fuel Injection Pump has a governor setup. The function of the governor is to check the engine idle RPM and when there is load, increase the fuel supply to maintain idle. Same thing is done by the ECM in CRDe engine. If the load of the compressor on the engine(even if its not connected to the ECM) is not much there will not be perceptible drop in RPM so no increased fuel supply or leading to increased idle RPM.

[nnn]

There is no drop in RPM as the ECM takes over and maintains a smooth idle with the A/C compressor on. I have idled my Thar with A/C on for over 30 minutes and it does not overheat.

Please see my post on " Advice on fitting an air conditioner in the Mahindra Thar" to resolve the overheating.

The Thar with its high low speed torque takes the A/c load with ease. The car accelerates from 1000 Rpm i.e 40 Kmph in top gear with A/C keeping up with normal city traffic with no hesitation.