Prob­lem might be linked to vac­uum

Austin American-Statesman - - D STATESMAN CARS - By­tom and Ray Magliozzi King Features Syn­di­cate Click 2012 audi a8l at a glance JA­SON YOUNG­BLOOD Orig­i­nal MSRP: Specs: Show­room: Deal­ers, we’re look­ing to pro­file unique or much-an­tic­i­pated ve­hi­cles coming to Cen­tral Texas show­rooms. E-mail Lisa Ogle at l

Dear Tom and Ray: I am in a band based out of Norman, Okla. Our record la­bel has pro­vided us with a Ford E350 van for tour­ing. Re­cently, we have up­graded to a larger, heav­ier trailer. With the trailer at­tached, the AC will cut out when­ever we ac­cel­er­ate or travel up an in­cline. What’s worse, when the AC cuts out, the heat au­to­mat­i­cally kicks on, full blast. Me­chan­ics have been un­able to re­pro­duce the is­sue and say that they’ve never heard of this prob­lem be­fore. It ap­pears to oc­cur more fre­quently as the tem­per­a­ture rises and we need the AC more. I’ve con­sid­ered that we are stress­ing the en­gine too much with the trailer and that the van is try­ing to siphon heat off the en­gine, but the temp gauge never budges. Since we are on the Texas coun­try cir­cuit, we nat­u­rally spend a lot of time in Texas. Hav­ing nine men in a van with no AC (or worse, the heat on full blast) in south­ern Texas leads to as­tound­ing lev­els of ... in­ter­est­ing odors. Please help!

— Luke

Ray: In ad­di­tion to a per­spi­ra­tion prob­lem, you have a vac­uum prob­lem, Luke.

Tom: There are lit­tle “blend doors” in the ducts of the ven­ti­la­tion sys­tem that open and close to di­rect hot and cold air to where you want it. Those doors are held open or closed by small vac­uum mo­tors.

Ray: And for some rea­son, those mo­tors aren’t get­ting enough vac­uum, es­pe­cially when the en­gine is un­der a con­di­tion we call “WOT,” or “wide-open throt­tle.”

Tom: The vac­uum is cre­ated by the en­gine, when the pis­tons go down and suck air into the cylin­ders. Vac­uum is at its high­est when the en­gine is idling and the throt­tle is closed (clos­ing the throt­tle is like putting your hand over the end of your vac­uum cleaner’s hose) and at its low­est when the throt­tle is wide open. And when would the throt­tle be wide open? When you’re try­ing to climb a hill in a van with nine large, sweaty dudes while tow­ing enough equip­ment to out­fit the Lawrence Welk orches­tra.

Ray: So, ei­ther you have lousy vac­uum to be­gin with and it’s fail­ing un­der high de­mand, or you have ad­e­quate vac­uum and it’s leak­ing out some­where along the way to those blend door mo­tors.

Tom: So, start with a sim­ple pres­sure test to see if your en­gine is pro­duc­ing enough vac­uum right at the in­take man­i­fold. That’s the Price: $84,700 As-tested price: $89,175 Mileage: 18 mpg city, 28 mpg high­way

En­gine: 4.2-liter V-8

$1,395 Al­loy en­gine that achieves 9,000 rpm, ca­pa­ble of 81 mph, en­gine out­put of 36-45 horse­power Unique features: It was the first Honda au­to­mo­bile to be of­fi­cially im­ported to the U.S.

First Texas

Honda Horse­power: 372 Torque: 388 pound-feet Trans­mis­sion: 8-speed au­to­matic

Drive wheels: All-wheel drive

This 1970 Honda N600 is on dis­play in the First Texas Honda show­room.

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