Switch off A/C at altitude

[cctdiag]

Hi

Could anybody please explain why there is a sign at the top of Yosimite Pass which asks drivers to switch off their cars air conditioning. I am presuming it has something to do with the effect of air prssure at altitude which could damge the A/C unit - but not being fridge minded can somebody help

many thanks

Jeff

 

[quark]

Car A/Cs are driven by the engine. Generally at high altitudes, air pressure is low and oxygen content also decreases. This won't provide exact stoichometric ratio of fuel and air for which it is designed. So the engine is derated at altitudes. Running AC will cause much load on the engine and you may not get enough torque to move the vehicle.

As far as ACs are concerned, you need not bother about air.
(except oper air refrigeration, like that used in planes while moving)

 

[pennpoint]

cctdiag;
Sorry! quark! nailed it. It has nothing to do with the air conditioner other than the Load it places upon the internal combustion engine which is starved for air/air pressure at that altitude.
Its a Public Service Message only. I speculate; Many a tourist has needed to be rescued from radiator boilover so "they" are attemting to reduce their losses by adding the sign.

pennpoint