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Old 10th November 2011, 21:08   #2581
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Default Re: Mahindra Scorpio : Issues & Solutions

^^ HVAC system pressure is monitored. Usually there is a pressure switch in the circuit (Trinary pressure switch) which monitors high pressure (blockage, faulty components) and low pressure (due to leaks). AFAIK, the compressor spec (for max and min pressure) is protected through this provision in the circuit.

Spike

PS- SST- Why do you think it must overheat? When the condenser fan fuse is removed so AC trips.
PPS- We have checked this (without any sophisticated instrumentation)-- no overheating.

Last edited by SPIKE ARRESTOR : 10th November 2011 at 21:17.
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Old 10th November 2011, 21:52   #2582
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Default Re: Mahindra Scorpio : Issues & Solutions

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Usually there is a pressure switch in the circuit
Hi,
Usually? Not in all Scorpios?

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Old 10th November 2011, 21:53   #2583
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PS- SST- Why do you think it must overheat? When the condenser fan fuse is removed so AC trips.
PPS- We have checked this (without any sophisticated instrumentation)-- no overheating.
Ok - so that's the safety net built into the wiring - but what would happen if you wire up the compressor to run, but stop the electric condenser fan from running?
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Old 10th November 2011, 22:12   #2584
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Default Re: Mahindra Scorpio : Issues & Solutions

Hi,
Someone post the Scorpio wiring diagram please.

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Sutripta
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Old 10th November 2011, 22:56   #2585
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Default Re: Mahindra Scorpio : Issues & Solutions

Dear All,

Today while cleaning the vehicle , my cousins driver broke the Key of the Hawk , grrrr..sigh !!!! , called up the ASC they say , i need to change the key set in the doors, re program the new key set all of which is going to cost me nearly 9k ..!!!

Do i have any other options ????
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Old 10th November 2011, 23:06   #2586
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Default Re: Mahindra Scorpio : Issues & Solutions

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Hi,
Usually? Not in all Scorpios?
All.

Quote:
Originally Posted by SS-Traveller View Post
Ok - so that's the safety net built into the wiring - but what would happen if you wire up the compressor to run, but stop the electric condenser fan from running?
I would paraphrase this question of yours-- What happens in a Thar (no condenser fan) with AC?

Spike
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Old 11th November 2011, 00:05   #2587
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Default Re: Mahindra Scorpio : Issues & Solutions

@SS & S

Do you guys think that Mahindra would design an engine that depended on the condensor fan to control engine temperature? The cooling system has to be designed to control engine temperature without depending on the condensor fan.
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Old 11th November 2011, 00:33   #2588
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Default Re: Mahindra Scorpio : Issues & Solutions

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Dear All,

Today while cleaning the vehicle , my cousins driver broke the Key of the Hawk , grrrr..sigh !!!! , called up the ASC they say , i need to change the key set in the doors, re program the new key set all of which is going to cost me nearly 9k ..!!!

Do i have any other options ????
Look around,and you might be able to get a new one made,for cheap.
the programmed chip can be transplanted from the old key to a new one.
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Old 11th November 2011, 07:29   #2589
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Ok - so that's the safety net built into the wiring - but what would happen if you wire up the compressor to run, but stop the electric condenser fan from running?
AFAIK, every AC compressor has an internal high pressure protection built in. This could be a pressure relief valve or a bursting disc. In the event of impermissible pressure being built up the discharge port is shorted to the suction port or the crankcase.
It is industry practice to not depend on external wiring and circuitry to prevent dangerously high pressures.

Low pressure protection is left to external circuitry to manage, since the consequences are not potentially dangerous.
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Old 11th November 2011, 07:42   #2590
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Default Re: Mahindra Scorpio : Issues & Solutions

Hi,

Is this ^ ^ (pressure) monitored then in a Compressor? Yes / no and how?

Spike
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Old 11th November 2011, 08:03   #2591
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Originally Posted by SPIKE ARRESTOR View Post
Hi,

Is this ^ ^ (pressure) monitored then in a Compressor? Yes / no and how?

Spike
Yes, this pressure is 'monitored' within the discharge port of the compressor. This is always a passive, 'pre-set' device, a valve or a bursting disc made of suitable material. Totally fail-safe.
For the old fashioned R22 compressors, for example, the in-built relief valve or the bursting disc would be set to blow at 20 bar.
The external control circuitry, if provided, would have the HP cut-out set at, say, 18 bar. If this fails, the in-built protection kicks in.
These are figures used in water cooled systems; values would differ for air cooled systems.

Last edited by anupmathur : 11th November 2011 at 08:04.
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Old 11th November 2011, 08:34   #2592
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Default Re: Mahindra Scorpio : Issues & Solutions

Hi,

I am aware of this ^^. Hydraulic devices (e.g compressors, HP pumps) must have an inbuilt safety device (e.g. relief valves, by pass etc) built into them. What I asked was regarding "external control circuit' as mentioned by you above. How does that happen?

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Old 11th November 2011, 08:48   #2593
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.... What I asked was regarding "external control circuit' as mentioned by you above. How does that happen?

Spike
Spike, I don't think our cars have any such external control circuit. There is no LP cut-out that I can see. There seems to be no HP cut-out either!
The compressor clutch is de-coupled in case of condenser fan failure?
This would not be fool proof; I suppose the inbuilt protection of the compressor would be called into play if discharge pressures go to dangerous limits.

Any details about the Scorpio HVAC system would be most welcome.
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Old 11th November 2011, 09:43   #2594
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I would paraphrase this question of yours-- What happens in a Thar (no condenser fan) with AC?
Thar? What AC? You guys left out the AC - or don't you remember? Then the after-market fitments have all kinds of modifictions - with fans, without fans, whatever. Any extensive regimented testing done by M&M while running AC without an additional electric fan?
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Old 11th November 2011, 10:31   #2595
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Originally Posted by Zed View Post

Try this - the next time the temp gauge starts going into the red zone, pull over and with the engine idling switch on the high beam \ try short bursts of the horn etc and look out for any sudden movements of the temp gauge needle. If you can spot some movements happening immediately when the hi-beam or horn is used, you can be rest assured that its an earthing problem with the electrical system. The first gen Scorpio had an earthing point somewhere near the wheel well...not sure if the design was changed in later variants.

Zed,

This morning, I had the same problem, again it was ephemeral. Was playing loud music (have an amplifier) and when the needle shot up, tried what you said.. honking, high-beam, loud music (don't know whether it matters)... didn't observe anything different.

And right from the beginning, there's no sudden movement (twitching) of needle ever. It was always smooth.

And by the way, discussion amongst you/ss/4x4/sa was very interesting and enlightening... keep it going.
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