2002 Corolla Turning the AC on when defrosting
in [Toyota]
|
Prev: C'mon now...how sneaky can you get?!?!?
Next: Brake lights staying on, cruise control not working
From: C. E. White on 28 Jul 2010 15:54 "JoeSpareBedroom" <newstrash(a)frontiernet.net> wrote in message news:Ue%3o.38604$KT3.31863(a)newsfe13.iad... > Beats me. All I know is what I observe, Ed: The sound, and the effect on > the RPMs, which is identical to what happens in summer. Well the next time the tempearture is down around zero F, turn on the A/C - if the compressor enagages you'll know it becasue of the squealing belt sound (if you are lucky) or the grinding sound of a compressor disentegrating (if you are unlucky). It only takes around 6 psia to turn R134 liquid at 0 degrees. Compressors aren't really designed to pump liquid - at least not for long. At 70 degrees F the pressure in the system should be over 50 psi with the compressor off. Take a look at http://www.ncttora.com/fsm/2003/Repair_Manual/03tacoma/ac/presw/ovi.pdf - The pressure switch inhibits the operation of the compressor when the refrigerant low side pressure is below 28 psi, or above 455 psi. At 32 degrees F the presuure in the system is going to be below 28 psi, so the compressor shouild not run at least when the vehicle is cold. Once the vehicle warms up, the underhood temperature may warm things up to allow the switch to close and the compressor to run, but if you are driving along in cold weather, the flow through the AC condensor should keep the refrigerant cold which will prevent the compressor from engaging. The A/C system also has a thermistor that provides temeparture information to the A/C controller (see http://www.ncttora.com/fsm/2003/Wiring_Manual/03tacoma/systemci/054ac.pdf ) I suspect this actually inhiits compressor operation based on the indicated temeparature at a temperature higher than the low pressure switch does, but the Toyota manual does not provide details on the actual operation of the control circuit in resposne to the thermistor input. See http://www.ncttora.com/fsm/2003/Repair_Manual/03tacoma/ac/ther1/insp.pdf The thermistor resistance is only shown over the range from 32 F to 77 F. I think they use it to switch off the compressor at low temperatures. But for sure the low pressure swwitch will prevent engagement of the compressor at tempertures below 32 F (assuming a properly charged system). Ed
From: JoeSpareBedroom on 28 Jul 2010 16:04 "C. E. White" <cewhite3(a)mindspring.com> wrote in message news:i2q1t5$9ok$1(a)news.eternal-september.org... > > "JoeSpareBedroom" <newstrash(a)frontiernet.net> wrote in message > news:Ue%3o.38604$KT3.31863(a)newsfe13.iad... > >> Beats me. All I know is what I observe, Ed: The sound, and the effect on >> the RPMs, which is identical to what happens in summer. > > Well the next time the tempearture is down around zero F, turn on the > A/C - if the compressor enagages you'll know it becasue of the squealing > belt sound (if you are lucky) or the grinding sound of a compressor > disentegrating (if you are unlucky). I guess the compressor's been disintegrating since the day I bought the truck, brand new.
From: Jeff Strickland on 28 Jul 2010 16:10 "C. E. White" <cewhite3(a)mindspring.com> wrote in message news:i2pv67$tj1$1(a)news.eternal-september.org... > > "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message > news:i2peh1$ird$1(a)news.eternal-september.org... >> >> "Jane Galt" <Jane_G(a)gulch.xyz> wrote in message > >>> My gas bill will notice it, and it puts wear on the compressor. >> >> You gas consumption from the AC isn't worth the discussion. Less than a >> few miles on a tank of gas. > > For years I have kept a gas mileage log book. I've never been able to find > a difference in mileage based on the time of the year (Winter/Fall/Spring > versus summer). This implies to me, the cost to run the A/C is negligible. > > As for wear, running the compressor occasionally is actually a good > thing - it assures the internal components and seals stay lubricated. > I agree. There can't be more of an affect than few miles on an entire tank of gas that comes from using the AC. One can do more harm to the fuel consumption by stomping the pedals than he can by being comfortable while he's stomping the pedals. I don't know how many miles per tank the AC will use but I'd expect less than 20, and probably less than 10. And, keeping the parts lubricated is never a bad idea.
From: Hachiroku ハチロク on 28 Jul 2010 16:29 On Wed, 28 Jul 2010 15:08:27 -0400, C. E. White wrote: > "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message > news:i2peh1$ird$1(a)news.eternal-september.org... >> >> "Jane Galt" <Jane_G(a)gulch.xyz> wrote in message > >>> My gas bill will notice it, and it puts wear on the compressor. >> >> You gas consumption from the AC isn't worth the discussion. Less than a >> few miles on a tank of gas. > > For years I have kept a gas mileage log book. I've never been able to find a > difference in mileage based on the time of the year (Winter/Fall/Spring > versus summer). This implies to me, the cost to run the A/C is negligible. I use the AC just about enough to keep the seals from drying out. I never ordered AC in cars, however, that has changed. :) I don't notice much of a difference between running the AC and driving at highway speeds, or driving at highway speeds with "260 air conditioning". I guess the amount of drag with the windows open equals the load placed on the engine with the compressor running. I DO notice about a 3 MPG difference from hot weather to cold weather, esp with the Mazda. ~27-28 MPG in the winter, and ~30-32 MPG in the summer. No AC 'cause it's busted, and R-12 to boot...
From: Jeff Strickland on 28 Jul 2010 16:31
"JoeSpareBedroom" <newstrash(a)frontiernet.net> wrote in message news:J304o.38606$KT3.37541(a)newsfe13.iad... > "C. E. White" <cewhite3(a)mindspring.com> wrote in message > news:i2q1t5$9ok$1(a)news.eternal-september.org... >> >> "JoeSpareBedroom" <newstrash(a)frontiernet.net> wrote in message >> news:Ue%3o.38604$KT3.31863(a)newsfe13.iad... >> >>> Beats me. All I know is what I observe, Ed: The sound, and the effect on >>> the RPMs, which is identical to what happens in summer. >> >> Well the next time the tempearture is down around zero F, turn on the >> A/C - if the compressor enagages you'll know it becasue of the squealing >> belt sound (if you are lucky) or the grinding sound of a compressor >> disentegrating (if you are unlucky). > > I guess the compressor's been disintegrating since the day I bought the > truck, brand new. > Have you physically looked at it? If the truck is adjusting itself properly, there will be no effect on the tach when the compressor is engaged, or not. Or the effect will be so small as to be unnoticable by looking at the tach. But whatever. Your entire argument is beside the point of the topic. |