AC compressor runs all the time?

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In my home AC, when the desired temp is reached, the AC compressor
turns off, and the house air circulation fan will continue running if
it is set to On instead of Auto at the thermostat.

In automobile AC, I have been under the impression that the compressor
runs all the time when the AC is on, even if the car is cool enough
inside.  (And the fan runs all the time too.)

And that with automatic automobile AC, the only thing that varies when
the car reaches its desired temperature is that the blend door moves
away from cooled air to warmed air.

Which means that part of the time I am routing engine heat to the
passenger compartment to warm the air that the AC makes too cool to
put into the pass. comp. without warm air to make it less cool.

What a waste of money that would be!

Am I right?

Thanks.

Re: AC compressor runs all the time?

On 7/28/2012 9:56 AM, micky wrote:

The waste of money is when you spent the extra bucks to get the
automatic climate control that does it...

The unit will cycle on and off if the pressure is too high or too low.

bob

Re: AC compressor runs all the time?

wrote:


I didn't want to buy an automatic AC but I didn't have any choice.

I only had two possibilities when my car blew its engine near
Asheville NC, and they both required driving 100 miles to see them. .


Re: AC compressor runs all the time?

wrote:


Somebody who knows your car can probably show you how to disable the
A/C compressor if you think it's costing you too much in "efficiency."
Maybe.
I used to pull the plug on my GM compressors in the fall, because I
didn't want it kicking on when using defrost mode in the winter.
Didn't need it.

--
Vic

Re: AC compressor runs all the time?

On Sat, 11 Aug 2012 17:53:45 -0500, Vic Smith


And for that matter, when one buys a high end model with a lot of
accessories, he's likely to get automatic heater/AC.   I don't know
why that didn't happen with the 3 Lebarons, '84', '88, and '95.  For
'65 and '67 (the year they were made, not the year I bought them) I
had Catalinas when the higher priced models were Bonnevilles. .

Unless one has the car made to order, but I usually buy cars 7 years
old.  This time it was 11 years old.  Can't get those made to order.


I like having AC, even when the weather was cooler and I only used it
5 or 10 days in the year, , but I don't like how difficult it is to
control it, and the heat as well.   With manual heat/AC, one moves the
temp lever and the output air changes temperature almost immediately,
in the time in the takes the air to get from the blend door to the
output vents, 2 or 3 seconds.   With automatic, I change the temp and
it seems to think about it, or it has a plan to gradually bring the
cabin air temp to the temp I set it at.,

(I would think it would maks the air very cold or hot to quickly bring
the average cabin air temp to what I set it to, and later it would
back off the temp of the output air to match the set temp.  But I
haven't seen any evidence of this.)

On a previous GM car when I didn't want the AC running just because I
had the defroster on (I don't care if it sometimes defrosts more
quickly that way) I put in a switch to turn it off absolutely, until I
wanted to turn it on.    

Then, with my 3 Chrysler Lebarons, it had such a switch already, from
the factory.

I haven't checked out this part of the wiring diagram yet, but
unfortunately, rather than an on/off toggle switch, , the AC is turned
on and off by a momentary switch, either the AC button or the Defrost
button. so I probably can't put in an absolute switch like I did in
the GM car and like the Chrysler cars came with.    Well, except by
running a pair of wires all the way from the AC clutch to the
dashboard.         So it looks like every time I turn on the Defrost,
I'll have to manually turn off the AC.   But this is just about
turning the AC off and that's not my big problem, it's the inability
to directly control the vent air temperature.


Well, that's a very good idea.   At least It will take care of 8
months.



Re: AC compressor runs all the time?




Ever hear of "KISS"? It means, "Keep it Simple, Silly". Who cares
if the AC comes on (or off) on Defrost. I've noted that my Defrost
works a LOT BETTER when AC comes on during Defrost. Of course, if
one wants to think that they know more than the engineers...  Also,
tinkering around like that VOIDS any or all warrantees.


 


Re: AC compressor runs all the time?


.

It is also good to have the AC run some in the winter months.  Keeps the
seals and other stuff lubercated. Bearings sitting in one spot long periods
of time tend to develope flat spots.



Re: AC compressor runs all the time?



Thanks for the reply. .

That refers to design, etc, not to being controlled by the design. .  
http://en.wikipedia.org/wiki/KISS_principle
The car has alredy been designed and they made it complicated.  They
made it so that turning on the Defrost turns on the AC, which is a
violation of KISS.  And why should I be dominated by them?


I do.  It wastes gas and puts more load on the engine. .


So you care, too.  You just like it the way that's it's designed.  

 I've noted that the defrosters works well enough without AC.  Maybe
we live in different areas of the country.   Plus one can wipe the
condensation off with a cloth.  That's the fastest method.


FWIW the engineers don't know me personally, and they are driven by
more factors than what I want.   For example, on the Solara, when one
puts the top down, all the windows go down.  That's very nice except
for higway trips or when I have a passenger I want to talk to,  and in
noisy parts of town (most places with 4 or more lanes of traffic), or
when it's moderately cool outl, then I want the windows up.    They
don't know that.  

Also on this car, unlike my previous 6 convertibles, the top won't go
up or down unless I'm going under 3 mph or less..   When it's starting
to rain  that's not good. Then I like to put the top up when I'm going
about 8 mph, which is fast enough to keep almost all of a light rain
out of the car, but more than slow enough not to hurt the top.
Actually 15 mph is okay,

I also do this when I'm putting the top down and leaving at the same
time, and even when I'm getting home and just don't want to waste
time.   From the manual,  I've identified the wire that prevents this,
and when I find the ECU that it's connected to, I'll cut the wire.

I don't, but If I always wanted the windows up, I'd find what make
them go down and disconnect it.

On a previous car, I didn't like it that the heater blew cold air
until the coolant warmed up, so I put a thermal switch in the coolant
hose that prevented the fan from working until the coolant was warm
enough.   I don't know if that is a problem with this car.

If something isn't the way I want it, I fix it if I can.


No. It voids warranties on the part of the car one has tinkered with.
If they tell you otherwise and won't repair something that is
unrelated to the tinkering and covered by the warranty, sue them.  

I don't think I have a warranty on my 12 year old car.

Re: AC compressor runs all the time?

On 8/13/2012 11:01 AM, micky wrote:

This is true except you have to be going backwards. :-)



Re: AC compressor runs all the time?

On Mon, 13 Aug 2012 11:21:09 -1000, dsi1



Re: AC compressor runs all the time?

On 8/13/2012 8:03 AM, Ralph Mowery wrote:

Yes, and that is one reason that the manufacturers made the AC come on
in defrost mode. The other reason is that it dries the air, which is
useful in damp conditions.

But some, like me enjoy having outside air come into the car, more or
less at outside temperature sometimes. Since they got rid of windwings
and the old kick panel vents, defrost brings fresh air into the car
without having the noise of open windows or the blast of air in the face
that you get through the AC vents in the dashboard.

Sometimes I want that air coming in the defroster duct to be cool and
dry, and sometimes, I want it just for ventilation. I, as owner of the
car should be able to chose when the compressor operates. Simple as that.

I should note that no American car I ever had with factory air let you
turn the compressor on or off independently. But I guess that has
changed over the years.

I still would prefer having windwings and kick panel vents. Even though
I no longer smoke. Having the windows down in traffic is just too damned
noisy.


Regards,

DAve

Re: AC compressor runs all the time?

wrote:


Yeah, I really miss those.   For my '73 Buick, I made one, sort of.  A
small sheet of lucite, part of which went into the window slot, and,
going up, was bent to be horizontal, and after a piece of pie shaped
piece that was horizontal, bent to go up.   So it blew air into the
passenger compartment, on me.  It was in front of the side view
mirror, which kept the wind from knocking it out of the slot**.

It was fun to bend the lucite.    I had a surplus 10" metal tube with
a heater in it, that heated the plastic the right amount (if I didn't
let it sit too long.)

But the next car, a Lebaron, had the side view mirror at the front end
of the door, so there was no good place to put my vent window.

(My cousin and uncle called such a window a "no draft" because air
could come in without a draft, but I opened them as wide as they could
go in order to get a draft.   Although on some cars I never owned they
wouldn't open wide enough to do that.)  My uncle smoked a lot.  Two of
his fingers were dark yellow.


I miss those too.  Far better breeze than anything that comes out of
any vent system in any car these days.   Last time I had them was the
'67 Ponitac convertible, which also had AC, but when AC became almost
standard, everyone I think stupidly omitted the kick panel vents.

On the '65 and maybe the '67 Pontiac convertibles, I could open the
vent window all the way so it blew on my face, open the kick panel
vent so it blew on my leg, and (Get this)  turn the sunvisor up and
forward, so it blew air that would have gone over my head to blow on
my face.   No matter how hot it got, I had enough breeze.   No sun
vixor has done that since in 1967 or maybe 73.


Yes, you raised a couple points I forgot.  Probably more important
ones than the ones I did remembe about why I want to turn the AC off
sometimes. .


Re: AC compressor runs all the time?

wrote:



Like I said before, you can probably put in a separate switch to keep
the compressor off in the winter.  Or unplug the wire to the clutch.
Depends on the wiring in the car.  For all I know some newer cars
might flash an engine code if you do it.
I ignore that stuff about running the A/C in the winter to "keep the
seals lubed" and other such nonsense.
Do you run your home A/C in the winter?  Didn't think so.
Anyway, I unplugged it for years on some cars with no issues.
I don't do it now, because my recent cars don't use that much more gas
turning the compressor, and winter haven't been as bad so I hardly use
defrost anyway.  Global warning probably.

--
Vic
  

Re: AC compressor runs all the time?

On Tue, 14 Aug 2012 21:52:50 -0500, Vic Smith


Well, this is embarrassing.  Another senior moment, maybe.  My OP was
only about whether the compressor ratn all the time when the AC was
on, but there's always thread drift and somewhere along the line, I
thought I couldn't turn off my Toyota AC when the defroster was on.
It's true that turring on the defrroster turns the AC on, but I can
turn it off a second later.  Sorry I said otherwise.        It's not
as good as the Chrysler AC from MY pov, but I know they can't make
everything just for me.


No, and I don't think anyone else does.  Good point.


On one of my Lebarons, the power steering leaked, and I had heard that
the fluid had to be there to lube the pump.  That's probably true on
some cars,, but eventually I got tired of filling it up every few
days, so I stopped for months.   I had no PS, which only matters when
one is going slow.  Months later I added some fluid and everything
worked good as new.  Did this a couple more times for months at a
time, PS always worked fine when filled.


Mine might not either.  It seems that way but I haven't really
checked.

 and winter haven't been as bad so I hardly use


Re: AC compressor runs all the time?

micky wrote:

Nope. The home A/C units use a sealed motor with no external seals.
The auto A/C uses a pair of seals plus internal seals which will get
stiff and fail.



Not what usually happens, BUT I would bet that not all of the fluid
leaked out either. Unless the leak was right in the bottom of the pump
or reservoir there would have still been fluid enough to keep the pump
lubed.


--
Steve W.

Re: AC compressor runs all the time?



Atleast someone understands the differance in a home sealed unit and the
compressor on a car that is driven externally and has external seals to
leak.

Also I have a heatpump for the house so it runs most every day.



Re: AC compressor runs all the time?

wrote:


Good point.  Hermetically sealed.  I give up.

--
Vic

Re: AC compressor runs all the time?

micky wrote:

Using full auto, the compressor will run most of the
time unless its below about 43F ambient.
IMO, its a waste of money and fuel.
With many cars you can turn off Auto.
Foreign made cars tend to have a switch to turn the
compressor on and off with out disturbing the rest
of the settings.  American cars do not have that.
We like to use lots of gasoline.

Re: AC compressor runs all the time?

micky wrote:

Depends on the car and the design of the system. Many cycle the
compressor based on pressure in the system and exterior temperatures.
Others cycle heat/cold to achieve the desired interior temp.

--
Steve W.

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