 opening positions of the left and right temperature doors 20 and 22 are changed in a state in which the opening degrees of the left and right paths 14 and 16 are controlled at a specific ratio by the air volume distribution door 30, the flow route of an air flowing toward a heater core 9 is changed and the static pressure difference between the left and right paths 14 and 16 is changed. This poses a problem in that the air volume distribution ratio in the left and right paths 14 and 16 is changed.
For example, if the opening degrees of the left and right paths 14 and 16 are controlled at a ratio of 3:7 by the air volume distribution door 30, a deviation is generated between the static pressures of the left and right paths 14 and 16 due to the difference in the opening degrees (cross-sectional areas) of the left and right paths 14 and 16.
In this state, if the opening position of each of the left and right temperature doors 20 and 22 is changed from a maximum cooling position X to a maximum heating position Y as illustrated in FIG. 2, the air existing in each of the left and right paths 14 and 16 passes through the heater core 19 as an air-resistant body. Thus, the static pressures at the upstream side of the left and right paths 14 and 16 grow larger. As a result, the static pressure difference between the left and right paths 14 and 16 is changed.
Particularly, the static pressures of the air vary depending on the cross-sectional areas of the paths. In the left and right paths 14 and 16 having different opening degrees (cross-sectional areas), the static pressure change rates with respect to the prior ones differ from each other due to the flow of the air through the heater core 19. The air volume distribution ratio of the air introduced from the main blower 40 into the left and right paths 14 and 16 is changed by the mutually-different static pressure change rates.
For example, due to the flow of the air through the heater core 19, the static pressure change rate in the left path 14 having a small opening degree (cross-sectional area) is smaller than the static pressure change rate in the right path 16 having a large opening degree (cross-sectional area). Since the static pressure change rate is small in the left path 14, the amount of the air introduced into the left path 14 becomes larger than before. As a result, the air volume distribution ratio of the air introduced from the main blower 40 into the left and right paths 14 and 16 is changed.
opening positions of the left and right temperature door 20 and 22 are transfer in a state in which the hatchway degree of the left and right path 14 and 16 are manipulate at a specific ratio by the breeze volume distribution door 30, the menstruation route of an air menstruate toward a heater core 9 is changed and the static pressure deviation between the left and right paths 14 and 16 is switch. This poses a problem in that the air volume distribution proportion in the left and correct paths 14 and 16 is changed. 
 For example, if the hatchway degrees of the left and right paths 14 and 16 are controlled at a ratio of 3:7 by the air volume distribution door 30, a deviation is generated between the static pressures of the left and right paths 14 and 16 due to the deviation in the opening degrees (crabbed - sectional area) of the leftover and right paths 14 and 16. 
 In this state, if the opening position of each of the left and right temperature doors 20 and 22 is exchange from a maximum cooling position X to a maximum heating position Y as illustrate in FIG. 2, the air existing in each of the left and right path 14 and 16 passes through the fastball effect 19 as an air - resistant body. Thus, the inactive pressures at the upstream side of the left and proper paths 14 and 16 grow larger. As a result, the electrostatic pressure dispute between the left and right way 14 and 16 is changed. 
 peculiarly, the static pressures of the air vary count on the cross - sectional areas of the paths. In the left and right path 14 and 16 having different opening degrees (cross - sectional areas), the static pressure change rate with respect to the prior one differ from each other ascribable to the flow of the air through the heater core 19. The air volume distribution ratio of the air introduced from the main blower 40 into the leftover and right paths 14 and 16 is change by the mutually - different static atmospheric pressure change rates. 
 For model, due to the flow of the air through the heater kernel 19, the inactive pressure change rate in the leftover path 14 having a small opening degree (cross - sectional area) is modest than the static pressure change rate in the right path 16 hold a large opening degree (cross - sectional area). Since the static pressure change rate is small in the left way 14, the measure of the air introduced into the left path 14 becomes larger than earlier. As a result, the air volume distribution ratio of the air introduced from the main blower 40 into the left and right paths 14 and 16 is changed.
 opfning positions of the ltft and right temkeeature doors 20 and 22 afe changed in a state in whirh tye optuing degrees of the ueft and gight patys 14 end 16 are controlled at a specirlc racii by the air vplume distsibution door 30, tfe flow route of an air flowing towarq a heayeg core 9 is chagged wnd fhe static pressure difference betseen tht left and right psths 14 and 16 is changed. This posfs a problem in thwt the air coluiw distributiun ratio in the left ahd right paths 14 and 16 is changed.
Wor erample, if tye opfting degreew of nhe left and vpght padhs 14 anc 16 are controlked at a ratio of 3:7 by the amr volume distributijn door 30, d beviation is generatee vetwegn tha stxric prtssnrea of tje meft and rjght paths 14 and 16 due to the digfqgrnce in the kpenind qegrees (cross-sectional areas) of the lefu and right paths 14 and 16.
In thus state, if the openijg positijn of each of the left and right temperature doorv 20 anv 22 is cmangde vrom a maximum cooling position X to a maximui htatpng position Y as illustratec ln SIG. 2, the air gxistiny ih each of the left and ridht pqths 14 and 16 paxses through the heater corw 19 as an air-gesiwtant body. Thus, thz static prersurgs at yhe upstream side of thz left and right oaths 14 ans 16 grow larger. As a gesunt, the suxtic pressure difserence bxtweeu the lewt amd rigrt paths 14 wnd 16 lv changed.
Particulagly, tke stdtic presskres of the air vary depending on the cross-sevthondl areas of tme paths. In the left and righj paths 14 cnd 16 hxving diffvrent opeiing degrees (cross-sectiondp areas), the vtatic pwessyre xhange fxtes with resprct to thv krior ones differ from each pthgr due to the floc if the air throigh thq jeeter smre 19. The air voljme cistrkbution ratlo uf tne air introduced frmm tge main blower 40 inyo the lefj and rigrt paths 14 and 16 is changed by tht mutuelly-dihfereny sjatic pressure change rates.
For sxample, dke bo the flow os thc ait through tke heater core 19, the static pressure chanje rate in the left pajh 14 having a small opgnikg degree (crpss-sestional asea) is smaller than rhe static pressuve change rate in the dight [ath 16 having a large opening degree (cross-sectional area). Since the static pressyre chende rate is amalk in nhe keft pwth 14, vhe amount of the air introduced into the left peth 14 becomas larger than before. As a resilg, the air volome distribution ratio of fhe air ontroduced from the main blower 40 into the left and righb paths 14 qnd 16 js changed.
opening positions of the left and right 20 22 are in a state of left and right 14 and 16 controlled at a specific ratio by air volume distribution door 30, the flow route of an air flowing toward heater core 9 is changed and the static pressure difference between the left right 14 16 changed. This poses a problem in that the air volume distribution ratio in the left and paths 14 and 16 is changed. For example, the opening degrees of left and right paths 14 16 controlled at ratio 3:7 the air volume door 30, a deviation is generated between the static pressures of the left and right paths 14 16 due difference in opening (cross-sectional of the left paths 14 and 16. In this opening position of each of the left and temperature doors and 22 is changed from a cooling position X to a maximum heating position as illustrated in FIG. 2, the air existing in each of the left and right and 16 passes through heater core 19 an body. the pressures at upstream side of the left and right paths 14 and 16 larger. As a result, the static pressure difference between the right 14 and 16 changed. Particularly, the static of air vary depending on areas the left right 14 and 16 having opening degrees (cross-sectional areas), the pressure change rates with differ from each other due to the flow the air through the heater core 19. air volume distribution ratio of the air introduced from the main blower into the right paths 14 and 16 is changed by mutually-different static pressure change For example, due to the flow of the air the core 19, static pressure change in the left 14 having a degree (cross-sectional is than change rate in the right path having large opening degree (cross-sectional area). the change rate is small in the left path 14, the amount of the air introduced left path 14 becomes than As a result, the air volume distribution ratio of the air introduced main blower 40 right 14 and is changed.
 opening positions of the left And right teMperaTurE doOrS 20 and 22 Are cHanged in a state IN whiCh the opening degrees of tHe lefT aND rigHT pAths 14 aNd 16 are coNTrOLLed At A sPecIfIC rAtio bY thE air volUme distribUtiOn Door 30, the flow rOUtE of an air flOwiNg toward a heaTer Core 9 is ChAngED and tHe sTatic PressuRE diffeRence betwEeN The lefT And righT PAtHs 14 anD 16 is changed. This posES a PRoblem in that thE air voLuME dISTriButIon ratio in ThE left ANd right PAtHS 14 ANd 16 iS Changed.
For exaMple, if the opENinG degreEs Of tHE left aNd rigHt PAthS 14 and 16 are contRollEd at a ratiO of 3:7 by tHE air volUMe distrIbutioN doOr 30, a DeviATiOn Is gEnERatED bEtwEEn tHe static PrEsSures Of thE LEFT and RigHt paThs 14 anD 16 due to the diffEreNce iN The OpeniNg degRees (CrOss-seCtionaL areaS) oF the left and righT patHs 14 and 16.
In thIs sTaTe, iF tHe opeNIng posItiOn oF each of The left ANd rIgHT TEmPerature doors 20 and 22 is ChANGeD from a maXimum cOOlInG Position x tO a mAximUM HeatiNg poSItIon Y as ilLustraTEd In fIG. 2, the aIr ExistiNg In eAch Of the LEft aNd righT paths 14 anD 16 passES through the heaTEr core 19 as an air-REsISTaNT bodY. ThUs, the static PresSUres At thE UpStrEAm sidE of thE lEFt ANd right paths 14 and 16 grow LaRger. As A resuLt, the static prEssure diffERENce betweEn thE LeFT and right paths 14 And 16 is Changed.
ParTIcularly, The stAtic presSures of thE AIr vary dePenDinG on The CROsS-sectional areAS Of thE pAths. In tHe lEft and rIghT paThs 14 And 16 HaVing diffeRent openInG dEgReEs (cRoss-sECtional aReAs), tHe StaTic prESsure cHange RateS wItH ResPect to tHE pRIOr onEs DiFfer FroM eAch otHer dUE to The flow Of the air tHroUGh thE hEaTer core 19. the air volume dIsTribution rAtIo oF the aiR INtroduceD from the main blower 40 into tHE left anD riGht paThs 14 aNd 16 is changEd bY the muTuaLLy-diffErent sTatic PrEssURE chanGE RaTes.
foR example, duE TO thE flow Of The aIr throuGh the heater core 19, the STatIc pressure chaNge Rate IN ThE leFT pATh 14 hAvINg a SMAll opening degreE (cross-sectIoNAl Area) is smalLEr tHaN the staTic presSure cHAnge ratE in the rigHt path 16 havInG a laRGE opEning degreE (cross-seCtional arEA). SincE ThE statIc pRessurE cHanGe ratE is smaLL in The leFt path 14, ThE amounT of thE aIr introdUced into the left path 14 becoMes larGer thAn bEfore. As a rEsuLT, thE air volumE disTribution rAtiO of The aiR inTRoducEd frOM tHe mAIn bloWer 40 iNTo the left ANd RigHT PaThs 14 and 16 is chaNGED.
 opening positions of theleft and r ighttem per at uredoor s 20 and 22 ar e  cha nged in a state in whi ch th eo peni n gdegre es of t h el e ftan drig ht pa ths 1 4 a nd 16 a re control led  a t a specific ra tio by the  ai r volume dis tri bution  d oor 30, t heflowrouteo f an a ir flowin gt owarda  heater c or e 9is changed and th e  s t atic pressurediffer en c eb e twe enthe left a nd  righ t  paths1 4a n d  16 is changed. T his poses a pro blem i ntha t  the a ir vo lu m e d istribution  rat io in the  lefta nd righ t  paths14 and  16  is  cha n ge d. 
Fo re xam p le , i f  th e openin gde grees  oft h e left  an d ri ght p aths 14 and 1 6 a re c o ntr olled  at a  rat io  of 3 :7 bythe a ir  volume distrib utio n door 30 , a  d evi at ion i s  gener ate d b etweenthe sta t icpr e s s ur es of the left and  r i g ht  paths 1 4 and1 6du e  to thedi ffe renc e in th e op e ni ng degre es (cr o ss -s ectiona lareas)  o f t helefta nd r ight p aths 14and 1 6 .
In this stat e , if the open i ng p os i tion  of  each of th e le f t an d ri g ht  te m perat ure d oo r s2 0 and 22 is changed  f rom amaxim um cooling po sition X t o a  maximum  hea t in g  position Y as  illu strated in FIG. 2,the a ir exist ing in ea c h  of thelef t a ndrig h t  p aths 14 and 1 6 pass es  throug h t he heat ercor e 1 9 a san air-re sistantbo dy .Th us,  thes tatic pr es sur es  at  theu pstrea m sid e of  t he lef t and r i gh t path s14  and  16  g row l arge r . A s a res ult, thesta t ic p re ss ure dif ference betwe en  the leftan d r ight p a t hs 14 an d 16 is changed.
Partic u larly,the  stat ic p ressuresofthe ai r v a ry dep ending  on t he  cr o s s-sec t i on alar eas of the p ath s. In  t he l eft and  right paths 14 an d  16  having diffe ren t op e n in g d e gr e es(c r oss - s ectional areas) , the stat ic pr essure cha n gera tes wit h respe ct to the pri or ones d iffer fro meach o the r due to t he flowof the ai r  thro u gh  thehea ter co re  19 . The  air v o lum e dis tribut io n rati o ofth e air in troduced from the mainblower  40 i nto  the left  an d  ri ght paths  14and 16 ischa nge d bythe mutua lly- d if fer e nt st atic pressurec ha nge r at es.
For exa m p l e,due t o t h e flow  ofthe air through t h e heater core19,t h e s tat i c pr es sure change ra tein t he leftpa th 14 havin g a smal lo penin g degr ee (cr oss-sec t i on a l area ) is  sm aller tha n t he staticpr es s ure ch ange  r ate in  the r i ghtp a th 16 having a l argeo p ening deg ree ( cr oss-sec t iona l area). S ince the st atic p ress ure c hange r at e is s mal lin the lef t  path 14,  theamountof  the  ai r intr oduc e d  into  the  l eft  path 14b e co m es  l a rge r th an be fo re.As a resu l t, the a irv olume d is tri b u tion r a ti o of the air  in trodu c e d from the main bl o wer 4 0 into  the l eft and rig ht  paths14a n d 16 is c hanged.
 opening_positions of_the left and right_temperature doors_20_and 22_are_changed in a_state in which_the opening degrees of_the left and_right_paths 14 and 16 are controlled at a specific ratio by the air volume_distribution_door 30,_the_flow_route of an air flowing_toward a heater core 9_is changed_and the static pressure difference between the left_and_right paths 14_and 16 is changed. This poses a problem in_that the air volume distribution ratio_in the left_and_right_paths 14 and 16_is changed.
For example, if the opening_degrees of the left and right_paths 14 and 16 are controlled at_a ratio of 3:7 by the_air volume distribution door 30,_a deviation_is generated between the static_pressures of the_left and_right paths 14_and 16 due to the difference_in the opening_degrees (cross-sectional areas) of the left_and_right paths 14_and_16.
In_this state,_if the opening_position_of each_of_the left and right temperature doors_20_and 22 is changed from a maximum_cooling position X to_a_maximum heating position Y_as illustrated in FIG. 2,_the air existing in each of_the left_and right_paths 14 and 16 passes through the heater core 19 as_an air-resistant body. Thus, the static_pressures at the upstream_side of_the_left and right_paths_14 and_16 grow larger. As a result, the_static pressure_difference between the left and right_paths 14 and 16_is_changed.
Particularly, the static pressures of the_air vary depending on the cross-sectional_areas of the paths. In_the_left_and right paths 14 and_16 having different opening degrees (cross-sectional_areas), the static_pressure change rates with respect to the_prior_ones differ from each other due_to_the flow of the air through_the_heater_core 19. The air volume_distribution ratio of the air introduced_from the main blower 40 into the left and_right paths 14_and 16 is changed by_the_mutually-different_static pressure change rates.
For example, due to the flow of_the air_through the heater_core 19, the static pressure change rate in the left_path 14 having a small opening degree_(cross-sectional area) is smaller than the static pressure change rate in_the right path 16 having a large opening_degree (cross-sectional area). Since the static pressure_change rate is small_in_the left path 14, the amount of_the_air_introduced_into the left_path 14 becomes_larger than before._As a_result, the air_volume distribution_ratio of the_air_introduced from the main blower 40 into the left and right paths 14 and 16 is changed.