Air Conditioning 101

·       HVAC — Heat­ing Ven­ti­la­tion Air Con­di­tion­ing.  Heat­ing and Air Con­di­tion­ing is sup­pos­ed­ly one dis­ci­pline but the real­i­ty is in the auto­mo­tive world 96% AC and 4% Heater.…

·       New Com­put­er Con­trolled AC sys­tems.  Lots of new­er air con­di­tion­ing sys­tems com­mu­ni­cate via an ECM.  The sys­tems are no longer iso­lat­ed and sep­a­rate from the rest of the motor.  This is frus­trat­ing for the do-it-your­selfers, but the ben­e­fit is by incor­po­rat­ing elec­tron­ics into the mix, many new­er fuel sav­ing strate­gies have come on line.

·       Vac­u­um Test­ing. Can’t say enough good things about our handy vac­u­um pumps/leak testers.  They make sure your sys­tems are leak free and won’t dump all your nifty new refrig­er­ant in one week, as well it flash­es all unwant­ed mois­ture out of your AC pip­ing and arter­ies.  Remem­ber water good in heaters and water BAD in Air Con­di­tion­ing Systems

·       AC Flush­ing. Lots of sol­id and gooey con­t­a­m­i­nants via too much water, hap­pens when those small dis­pos­able quick­ie ac recharge kits are used with­out prop­er pulling the water out of your sys­tem before recharg­ing it.  Those too good to be true cheap kits most­ly wreak hav­oc on the fixed spray points of the Ori­fice Tubes and the Expan­sion Valves.  When we can’t get com­mu­ni­ca­tion between the high side and low, we flush.  That usu­al­ly does the trick.

·       Receiv­er Dry­er. Old­er tech­nol­o­gy than the accu­mu­la­tor but works great and has a water remov­ing des­ic­cant bag that keeps the mois­ture to a min­i­mum.  When this thing gets gooey inside it releas­es con­t­a­m­i­nants that clog small pin­hole pas­sage-ways like in the expan­sion valve.

·       Expan­sion Valve. This is also old­er tech­nol­o­gy but has a vari­able ori­fice aspect to it that reduces the load on the com­pres­sor when not so hot out­side. This saves fuel and there­fore Expan­sion Valve plat­forms are mak­ing a come­back.  You will find them in high­er end sys­tems as well as big­ger trucks

·       Com­pres­sor.  This guy com­bined with the Con­denser and Evap­o­ra­tor almost feels like an accor­dion per­for­mance on the Lawrence Welk Show. Yes, my grand­moth­er forced me to watch it with her on Sun­day evenings. The Com­pres­sor pulls (stretch­es) cool liq­uid refrig­er­ant into a cool­er gas, and push­es (com­press­es) hot gas back into a hot­ter liq­uid. Real­ly quite exit­ing, almost as excit­ing for me as Sun­day evenings with Mr. Welk was for my Grandmother.

·       Con­denser. Takes a too hot to han­dle gas refrig­er­ant (most like­ly R134a) and pounds it into sub­mis­sion.  As long as you have enough refrig­er­ant in your sys­tem the Con­denser zone will be the area that the hot gas gets con­densed back into a liq­uid.  But you got to have the juice or for­get about it. Any low lev­els on refrig­er­ant it will stay a gas.

·       Evap­o­ra­tor. This is where the mag­ic hap­pens.  Found in your hot dash board, it mirac­u­lous­ly pours oh so cold air into your lit­tle mobile eco-sys­tem.  The evap­o­ra­tor receives a fine misty cloud of small refrig­er­ant droplets and flash­es them into a gas.  The spray of refrig­er­ant won’t occur if it is sub­merged due to too much refrig­er­ant.  Too much juice no mag­ic cool­ing box.  Worse yet your com­pres­sor will take a dump on you.  You bet­ter not over­charge your sys­tem with one of those lame all in one kits.

·       Pres­sure Switch.  Don’t bypass this switch.  If your pres­sure switch is stuck on with­out much refrig­er­ant, it will cause the sys­tem to run emp­ty.  This is bad, kind of like run­ning a trans­mis­sion with­out any ATF.  Caus­es dam­age but not quite as sud­den and cat­a­stroph­ic as run­ning a motor with­out the motor oil.  None the less per­ma­nent and expen­sive.  Pres­sure switch­es are designed to shut the whole sys­tem down to save you mon­ey and heartache.

·       Accu­mu­la­tor / Dehy­dra­tor. This guy has a nifty way of gath­er­ing up all the liq­uid refrig­er­ant and keep­ing it sep­a­rate from the gas.  Com­pres­sors absolute­ly don’t like com­press­ing liq­uid and a prop­er­ly func­tion­ing accu­mu­la­tor keeps the com­pres­sor hap­py.  Always found with Ori­fice Tubes.

·       Fixed Ori­fice Tube (FOT). Also called the expan­sion tube. Don’t want this guy clogged with con­t­a­m­i­na­tion.  It needs to make a fine spray.  Its pur­pose is to make small droplets of refrig­er­ant from large droplets.  It’s much eas­i­er to flash a small droplet into a gas than a big droplet. Always found with Accumulators

·       R‑134a refrig­er­ant.  This is the bread and but­ter refrig­er­ant found in all new auto­mo­tive appli­ca­tions.  Rumor has it new refrig­er­ants are “right around the cor­ner,” but this is only on a fly­er on my desk which cre­ates fear in me and forces me to pay for five class spots in next month’s HVAC update class.  Got keep the mon­ey local and flow­ing right?

·       NU-R22b refrig­er­ant. Tru­ly bad #ss refrig­er­ant, usu­al­ly found on larg­er passenger/tour busses or on yachts.  Much, much cool­er than the R‑22a!!  It has the same high effi­cien­cy cool­ing capa­bil­i­ties of the old R‑22 with all the safe envi­ron­men­tal aspects of the R‑22a. Pre­vents both the lefts and rights from get­ting hot and bothered.

·       High Pres­sure Side. Goes hot­ter when the com­pres­sor forces the gas back into a liquid

·       Low Pres­sure Side. Goes cold­er when pulls liq­uid into a gas.  Arter­ies can’t be clogged or none of this will work efficiently.