Dear JB,

    How come air conditioners on cars only fail when it's 100 degrees in the shade?  And I'll hang up and listen to your answer... I mean, I'll mail this and wait for you to answer... I mean, oh, you know what I mean, just answer the question!

signed,
Hot Under The Collar

Dear Collar,

    That's a good question.  Sort of like why tires only go flat when it's raining and you stand there wondering where the jack is, how to use the flimsy looking contraption, why the manufacturer designed it so that you have to lay down to use it and, finally, why am I hauling all this junk in my trunk?  What was your question again?  Oh, yes, air conditioners. Cars, more so than other appliances you own, are extremely temperature sensitive.  At seventy degrees fahrenheit even broken down cars will run forever.  But let the temperature creep into the nineties and seemingly insignificant problems will leave you strategically stranded on the freeway at the exact midpoint of a thirty-

five mile stretch between exit ramps.  You now get to guess which exit might have a garage located near it and start walking in that direction. I would recommend walking back toward the last exit for a number of reasons.  For one, it is unnerving to me to have as the only assurance that one of the endless stream of cars and trucks is not running out of the road to hit me from behind be the fact that I lived to see them pass by. 

Anyway, heat is what tears up air conditioners.  You see, its only job is to move heat around.  It moves it from the interior of your car to a point just in front of the radiator where it releases it so that it can wash back over the entire vehicle.  Makes sense to do it that way doesn't it?  That way the heat released by the air conditioner can help overheat your engine and maybe ruin it.  The reason your air conditioning fails on a hot day is that the pressure required to circulate the refrigerant is much higher because it is carrying

more heat around in it.  This helps destroy compressors and hoses especially if they are already weak.


By the way, Collar, thanks for taking up all the space for this month with your one question.  When you see some poor sap walking down the freeway to get help remember it may have been YOU who knocked him

out of getting his car fixed right here!

JB can be seen each Thursday morning on WDEF-TV News 12's Morning Show at 7:30 A.M. where he answers your car questions.  He can also be heard Saturday Mornings 7-9 on Talk Radio 102.3 FM on the Saturday Morning Garage.  He spends the rest of his time taking advantage of helpless motorists at North Shore Auto Repair in Chattanooga.  E-mail JB at jeepster1515@yahoo.com to have your car care question answered in this column.