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Originally Posted by Zed 1. The coolant will not overheat on account of the electric fan not working (or failing) since the visco fan takes care of airflow through radiator. |
Not necessary, depends on the prevailing "conditions" (external as well as internal).
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2. Therefore the AC compressor 'cut-out' would be the first noticeable effect (in stop go traffic) if there is an electric fan failure since the AC condenser will be dependant on the electric fan on account of nil ram air.
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Compressor will cut off and cut in due to the change in pressure within the AC circuit.
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Originally Posted by SS-Traveller That there's no way a car can overheat if the electric fan does not work? |
There are chances it will overheat, all depends on the "conditions".
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Originally Posted by Zed Most R-WD vehicles - Sumo, Scorpio, Xylo, Qualis, Innova (and also some of the premium SUVs ) have an engine powered fan normally with a viscous coupling to regulate fan speeds. In any of these vehicles you can take the electric fan out and even at max ambient limit ( 45 Deg C ) the engine will not overheat - as long as the cooling system components are in working order (thermostat, coolant pump, no cavitation \ fin damage in raditor and correct coolant level).
To make my point clearer - the Innova has no electric fan. The visco fan also doubles up as the condenser fan - this is achieved by a combining radiator design \ layout with an appropriate fan diameter and visco clutch setting.
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Point valid up to an extent but not necessary.
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Originally Posted by 4x4addict
Electric fan is not redundant, but as Zed points out it is for cooling the condenser/AC gas and not for the engine per se. As you can see many people are running Thar CRDe with condenser without the additional electric fan for the condenser without any heating issues. AC will be more effective with the electric condenser fan. |
Ok, you got a point.
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In one of earlier SUV which was black in color, I felt the AC was ineffective on very hot days. On diagnosis, I found that the wiring harness for the dual condensor fans had shorted and the condensor fan was not working. Only the radiator fan was working. I never had any heating issues, but only less efficient cooling of Ac.
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Ok.
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There is absolutely direct heat exhange between the AC cooling system and engine cooling system. AC compressor adds some more load on the engine, but that additional load of the AC compressor shouldn't cause the engine to heat in modern powerful engines. This may have been the case for older wheezier diesel engines.
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Agree, but not necessary.
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Originally Posted by 4x4addict @spike:
Query is "If condenser fan fails, will the Scorpio engine over heat?" |
You were referring specifically to Scorpio, which I missed in my earlier post and interpreted it as a generic query. The answer cannot be a simple 'Yes' or 'No'.
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Originally Posted by Aroy
. Extra load of AC on the engine, when you are stationary
. Heat leaking from condenser to radiator. but normally with a fan coupled to the engine, the fan is also rotating slower thus pumping in less air, and that coupled with extra heat load passed on by the condenser will present a higher load on the radiator, |
These are some of the conditions. ^^
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Originally Posted by Zed The radiator fan has to clear the cooling requirements of a given vehicle - which is basically the vehicle running at max operating ambient, with full load (perhaps even an overload factor) and the engine running continuously at the max torque and max power rpms. |
What air speeds (general) are we looking at when we compare Radiator and Condenser fans?
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If the AC condenser fan malfunctions, the AC compressor gets disengaged and hence the question of the AC condenser reaching inordinately high temperatures does not arise.
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Are you sure on this?
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Originally Posted by SPIKE ARRESTOR No |
Depending on the "conditions". I should have elaborated more on why 'No' and when "Yes'.
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Originally Posted by 4x4addict @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. |
Lol, thinking about what all I have seen, this had me laughing.
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Originally Posted by anupmathur 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. |
There is a twist to this, I am eagerly awaiting to see the Compressor drawings before commenting on this any further. Will update once I get concrete info.
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Originally Posted by Zed
Remember that the temp gauge has a dead zone - ie from starting point to about 60 or 65 deg - the sensitivity \ accuracy is very low and from 80 - 100 the sensitivity is high. This is by design.
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Hmm. You know this, good.
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Originally Posted by SS-Traveller
I wonder if Spike would be so forthright with his answer to Tini's question... |
Well if you ask a generic question it will be 'No' but if it is specific to Scorpio it will have a tendency to overheat / go beyond normal operating temperatures at certain conditions, otherwise it will be operating in safe zone despite condenser failure.
I was talking to one of my friends who is also a Vehicle Test Engineer (Cooling system specialist). He has tested some of these in India and abroad. He tells me that newer ones behave satisfactorily even with a disconnected / removed Condenser fan, only when the ambient is severe the problems begin to arise. The ambient he is referring to is ~ 55 found in regions of Rajasthan (where these vehicles are mostly tested for cooling performance in India).
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Originally Posted by Zed T
The condenser fan is responsible for reacting to cooling demand from the HVAC system and keeps the condenser at the right temperature. It is certainly not redundant. However it does not play a role in the engine thermal management loop. |
Yes,
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Originally Posted by Zed @ AnupMathur - Contrary to popular perception - Start stop traffic (even at high ambient) does not represent the worst case scenario for engine cooling. The worst case scenario is when the engine runs at max torque rpm, with max load at maximum operating ambient temperature. Im being specific with regards to the Crde engine on the 2005 scorpio. |
Why 2005 Crde Scorpio only?
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It is the job of the primary radiator cooling fan to keep the coolant temperature within a certain 'rise over ambient' limit during the cooling trials (Part of vehicle validation). The cooling trial involves not just the vehicle under full load but also a second vehicle (wiht its brakes partly depressed) to create the 'max torque' situation. The AC condenser fan plays no role in the cooling test.
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You seem to know a few things about cooling trials. It would be great if you could share something on Cooling system performance tests like what all tests are done, what is the acceptance criteria etc. I am asking you specifically because the importance of the words in bold (above) are mostly known to people who have either conducted or witnessed the cooling 'trials'.
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Just to repeat what was mentioned in an earlier post - if the condenser fan fails - the AC compressor gets cut off. There is no way a scorpio can overheat on account of a condenser fan failure - UNLESS the cooling system is not in good shape in the vehicle we are talking about.
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Well, actually there is a way. What if the Compressor is still engaged (cut in / cut off happening due to pressure surge)?
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Any M&M engineers to back me up please ? |
Not one, but agree to some of the things mentioned by you (especially that word, which brought back some old memories).
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Originally Posted by Sutripta ^^^
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Scorpio specific.
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Don't have that data, but can manipulate from things available with me. Not needed here anyway.
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Originally Posted by SS-Traveller Also, why sidestep the moot question...? |
No sidestepping. I prefer to stay away when posts turn towards 'impugning' route. I was also away (literally) for some time.
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Originally Posted by Styler I have a 2003 Non-CRDE Scorpio done 85,000 kms. ------ |
Interesting point but things have come a long way since 2003. Right from Radiator, Pump, Condenser, Lubricants, Fans, Instrument gauges etc.
So, to sum it up-
Will any car overheat if condenser fan fails? No / Yes (depending on the prevailing conditions and vehicle configuration)
Will Scorpio overheat if condenser fan fails? No (favorable conditions) / Yes (severe ambient conditions and Compressor in action for prolonged times).
I hope this makes things clearer.
Spike
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