Auto AC questions

2008 Kia Rondo, 2.7 liter engine.
AC cools for 8-10 minutes and then warm air for the next 5-10 minutes. This action continues on and on.

Please note that this car has an s..load of sensors that may or may not trigger the compressor clutch solenoid.

Took it to a mechanic (highly recommended for diagnostics)and authorized 2-3 hours of work. System charge and pressures are right on target. Could not find the problem. ($270)

Took it to the Kia dealer ($150 diagnostics) and they agree that the pressures are fine, but, the compressor is weak. Can replace the compressor for a mere $1,350.

Way more money than what I have. Tempted to wire a push button or toggle to the relay and mechanically force the clutch to go on while driving.

Kia reminded me that the compressor itself is $800. That leaves about $500± for them to play with.

I used to do auto air about 30 years ago when things were simpler. Still have gages, leak detector etc. Can't believe that a weak compressor would for some reason cycle on and off, although I do realize that pressures are probably being read (sensed)on both the low and high sides of the comp.

Any advise greatly appreciated.

Ivan Vegvary

On Wed, 16 Jul 2014 19:52:25 -0700 (PDT), Ivan Vegvary
> wrote:

>2008 Kia Rondo, 2.7 liter engine.
>AC cools for 8-10 minutes and then warm air for the next 5-10 minutes. This action continues on and on.
>
>Please note that this car has an s..load of sensors that may or may not trigger the compressor clutch solenoid.
>
>Took it to a mechanic (highly recommended for diagnostics)and authorized 2-3 hours of work. System charge and pressures are right on target. Could not find the problem. ($270)
>
>Took it to the Kia dealer ($150 diagnostics) and they agree that the pressures are fine, but, the compressor is weak. Can replace the compressor for a mere $1,350.
>
>Way more money than what I have. Tempted to wire a push button or toggle to the relay and mechanically force the clutch to go on while driving.
>
>Kia reminded me that the compressor itself is $800. That leaves about $500± for them to play with.
>
>I used to do auto air about 30 years ago when things were simpler. Still have gages, leak detector etc. Can't believe that a weak compressor would for some reason cycle on and off, although I do realize that pressures are probably being read (sensed)on both the low and high sides of the comp.
>
>Any advise greatly appreciated.
>
>Ivan Vegvary

Is the high speed cooling fan working? Does the AC stay cold at
highway speeds, and only act up in traffic? If so, it's probably the
fan.

What are the pressures when it's working, and then when it blows warm?
Is it possible there's moisture in the system? Is the air flow through
the condenser restricted?

Bill Vanek > wrote in
:

> On Wed, 16 Jul 2014 19:52:25 -0700 (PDT), Ivan Vegvary
> > wrote:
>
>>2008 Kia Rondo, 2.7 liter engine.
>>AC cools for 8-10 minutes and then warm air for the next 5-10 minutes.
>> This action continues on and on.
>>
>>Please note that this car has an s..load of sensors that may or may
>>not trigger the compressor clutch solenoid.
>>
>>Took it to a mechanic (highly recommended for diagnostics)and
>>authorized 2-3 hours of work. System charge and pressures are right
>>on target. Could not find the problem. ($270)
>>
>>Took it to the Kia dealer ($150 diagnostics) and they agree that the
>>pressures are fine, but, the compressor is weak. Can replace the
>>compressor for a mere $1,350.
>>
>>Way more money than what I have. Tempted to wire a push button or
>>toggle to the relay and mechanically force the clutch to go on while
>>driving.
>>
>>Kia reminded me that the compressor itself is $800. That leaves about
>>$500± for them to play with.
>>
>>I used to do auto air about 30 years ago when things were simpler.
>>Still have gages, leak detector etc. Can't believe that a weak
>>compressor would for some reason cycle on and off, although I do
>>realize that pressures are probably being read (sensed)on both the low
>>and high sides of the comp.
>>
>>Any advise greatly appreciated.
>>
>>Ivan Vegvary
>
> Is the high speed cooling fan working? Does the AC stay cold at
> highway speeds, and only act up in traffic? If so, it's probably the
> fan.
>
> What are the pressures when it's working, and then when it blows warm?
> Is it possible there's moisture in the system? Is the air flow through
> the condenser restricted?
>

make sure your evap drain tube is open, may just be freezing up and
melting, ect. KB

Thank you for your answer. I will take pressure readings on Friday and report.
Thanks,
Ivan Vegvary

> Is the high speed cooling fan working? Does the AC stay cold at
>
> highway speeds, and only act up in traffic? If so, it's probably the
>
> fan.
>
>
>
> What are the pressures when it's working, and then when it blows warm?
>
> Is it possible there's moisture in the system? Is the air flow through
>
> the condenser restricted?

Bill, thanks for your response. Here are some readings.

Ambient 76°-80°; Relative humidity 72%
Turn on car.
AC (clutch) engages
At 2000 rpm Low=35psi; High=205psi; Cabin vent temp (CVT) = 32°
At 650 idle Low= 32psi; H=150 CVT = 28°

CLUTCH DISENGAGES AFTER ABOUT 15 MINUTES.

Only after waiting an additional 20 minutes and trying all controls, including engine off, engine on, clutch somehow re-engages. Tapping on AC relay makes no difference.
When re-engaged (by now ambient is 80°)
At 650 idle Low=45 High=210 CVT =40°
At 2000 rpm Low=32, High=270 CVT=36°

Bill, if this gives you any clues, please advise. As stated previously:

Independent mechanic "Something in the computer module is not triggering the AC relay. All other voltages, including the thermistor check out OK.

Dealer "Compressor weak" = $1500

On Sat, 19 Jul 2014 12:44:22 -0700 (PDT), Ivan Vegvary
> wrote:

>
>> Is the high speed cooling fan working? Does the AC stay cold at
>>
>> highway speeds, and only act up in traffic? If so, it's probably the
>>
>> fan.
>>
>>
>>
>> What are the pressures when it's working, and then when it blows warm?
>>
>> Is it possible there's moisture in the system? Is the air flow through
>>
>> the condenser restricted?
>
>Bill, thanks for your response. Here are some readings.
>
>Ambient 76°-80°; Relative humidity 72%
>Turn on car.
>AC (clutch) engages
>At 2000 rpm Low=35psi; High=205psi; Cabin vent temp (CVT) = 32°
>At 650 idle Low= 32psi; H=150 CVT = 28°
>
>CLUTCH DISENGAGES AFTER ABOUT 15 MINUTES.
>
>Only after waiting an additional 20 minutes and trying all controls, including engine off, engine on, clutch somehow re-engages. Tapping on AC relay makes no difference.
>When re-engaged (by now ambient is 80°)
>At 650 idle Low=45 High=210 CVT =40°
>At 2000 rpm Low=32, High=270 CVT=36°
>
>Bill, if this gives you any clues, please advise. As stated previously:
>
>Independent mechanic "Something in the computer module is not triggering the AC relay. All other voltages, including the thermistor check out OK.
>
>Dealer "Compressor weak" = $1500

So are you saying that the compressor turns off while the readings are
steady at 32 & 150? And what happens after it comes back on? Does it
continue to work, or does it once again turn off after about 15
minutes? And does the system always behave the same?

There are certain inputs to the computer that will turn off the AC for
protection or other reasons, and I can't remember what all of them
are. WOT will turn it off on at least some cars, and high coolant
temperature, and I'm sure there's other things. Is the engine getting
hot? Can you read the coolant temperature?

I am also assuming that you know that the clutch is not being
commanded on, and failing to engage.

If those readings do hold steady at 32 & 150, and it still turns off,
there is either another AC system sensor that I'm not aware of (I'm
not familiar with this car at all), or another input to the computer
telling it to turn off the AC. It does not sound like the cooling fan.
Do you have a wiring diagram that shows all of the sensors?

Even though it doesn't sound like the high speed cooling fan, is that
fan coming on?

And it seems that the only way it could be the compressor is if it's
being commanded on, and not coming on because of the coil, or a wiring
issue at the compressor.

On Sat, 19 Jul 2014 14:00:08 -0700, Bill Vanek >
wrote:

>On Sat, 19 Jul 2014 12:44:22 -0700 (PDT), Ivan Vegvary
> wrote:
>
>>
>>> Is the high speed cooling fan working? Does the AC stay cold at
>>>
>>> highway speeds, and only act up in traffic? If so, it's probably the
>>>
>>> fan.
>>>
>>>
>>>
>>> What are the pressures when it's working, and then when it blows warm?
>>>
>>> Is it possible there's moisture in the system? Is the air flow through
>>>
>>> the condenser restricted?
>>
>>Bill, thanks for your response. Here are some readings.
>>
>>Ambient 76°-80°; Relative humidity 72%
>>Turn on car.
>>AC (clutch) engages
>>At 2000 rpm Low=35psi; High=205psi; Cabin vent temp (CVT) = 32°
>>At 650 idle Low= 32psi; H=150 CVT = 28°
>>
>>CLUTCH DISENGAGES AFTER ABOUT 15 MINUTES.
>>
>>Only after waiting an additional 20 minutes and trying all controls, including engine off, engine on, clutch somehow re-engages. Tapping on AC relay makes no difference.
>>When re-engaged (by now ambient is 80°)
>>At 650 idle Low=45 High=210 CVT =40°
>>At 2000 rpm Low=32, High=270 CVT=36°
>>
>>Bill, if this gives you any clues, please advise. As stated previously:
>>
>>Independent mechanic "Something in the computer module is not triggering the AC relay. All other voltages, including the thermistor check out OK.
>>
>>Dealer "Compressor weak" = $1500
>
>So are you saying that the compressor turns off while the readings are
>steady at 32 & 150? And what happens after it comes back on? Does it
>continue to work, or does it once again turn off after about 15
>minutes? And does the system always behave the same?
>
>There are certain inputs to the computer that will turn off the AC for
>protection or other reasons, and I can't remember what all of them
>are. WOT will turn it off on at least some cars, and high coolant
>temperature, and I'm sure there's other things. Is the engine getting
>hot? Can you read the coolant temperature?
>
>I am also assuming that you know that the clutch is not being
>commanded on, and failing to engage.
>
>If those readings do hold steady at 32 & 150, and it still turns off,
>there is either another AC system sensor that I'm not aware of (I'm
>not familiar with this car at all), or another input to the computer
>telling it to turn off the AC. It does not sound like the cooling fan.
>Do you have a wiring diagram that shows all of the sensors?
>
>Even though it doesn't sound like the high speed cooling fan, is that
>fan coming on?
>
>And it seems that the only way it could be the compressor is if it's
>being commanded on, and not coming on because of the coil, or a wiring
>issue at the compressor.

There is one other thing. I just Googled this, and I noticed that your
outlet temp was 28 degrees. There is a thermistor on your evaporator
that might be shutting the system down. 28 degrees seems awfully cold,
but I don't know what is supposed to prevent that on your system. Is
it a cycling system?

On Wed, 16 Jul 2014 19:52:25 -0700 (PDT), Ivan Vegvary
> wrote:

>2008 Kia Rondo, 2.7 liter engine.
>AC cools for 8-10 minutes and then warm air for the next 5-10 minutes. This action continues on and on.
>
>Please note that this car has an s..load of sensors that may or may not trigger the compressor clutch solenoid.
>
>Took it to a mechanic (highly recommended for diagnostics)and authorized 2-3 hours of work. System charge and pressures are right on target. Could not find the problem. ($270)
>
>Took it to the Kia dealer ($150 diagnostics) and they agree that the pressures are fine, but, the compressor is weak. Can replace the compressor for a mere $1,350.
>
>Way more money than what I have. Tempted to wire a push button or toggle to the relay and mechanically force the clutch to go on while driving.
>
>Kia reminded me that the compressor itself is $800. That leaves about $500± for them to play with.
>
>I used to do auto air about 30 years ago when things were simpler. Still have gages, leak detector etc. Can't believe that a weak compressor would for some reason cycle on and off, although I do realize that pressures are probably being read (sensed)on both the low and high sides of the comp.
>
>Any advise greatly appreciated.
>
>Ivan Vegvary

In addition to the things others have mentioned I would take a look at
the low pressure switch IF your system has one. On my vehicles it's a
switch with two wires on the low pressure (should feel cool or cold)
line. When the pressure drops to around 28 psi it clicks off and
shuts off the compressor. If it doesn't click back "on" then
naturally the compressor won't come back on. You can pull the
connector off it and just jumper the connector so that it's always on
and see if that keeps the ac running after the 15 minutes goes by.

If the evap coil is freezing up you should notice a reduction in
airflow thru it. I've had cars where it would freeze up and the
airflow would get cut in half and it would not be very cool, but it's
usually still going to be somewhat cool rather then warm even if it
freezes up.

Ivan Vegvary wrote:
> 2008 Kia Rondo, 2.7 liter engine. AC cools for 8-10 minutes and then
> warm air for the next 5-10 minutes. This action continues on and
> on.
>
> Please note that this car has an s..load of sensors that may or may
> not trigger the compressor clutch solenoid.
>
> Took it to a mechanic (highly recommended for diagnostics)and
> authorized 2-3 hours of work. System charge and pressures are right
> on target. Could not find the problem. ($270)
>
> Took it to the Kia dealer ($150 diagnostics) and they agree that the
> pressures are fine, but, the compressor is weak. Can replace the
> compressor for a mere $1,350.
>
> Way more money than what I have. Tempted to wire a push button or
> toggle to the relay and mechanically force the clutch to go on while
> driving.
>
> Kia reminded me that the compressor itself is $800. That leaves
> about $500± for them to play with.
>
> I used to do auto air about 30 years ago when things were simpler.
> Still have gages, leak detector etc. Can't believe that a weak
> compressor would for some reason cycle on and off, although I do
> realize that pressures are probably being read (sensed)on both the
> low and high sides of the comp.
>
> Any advise greatly appreciated.
>
> Ivan Vegvary
>

you don't say if it is the Automatic or the Manual system but in either
case the compressor is turned on by the relay, and the relay is
controlled by the PCM. The PCM is /told/ whether or not to control the
relay by the AC control module. The AC control module is the one that
gets sensor input. Without the proper scan tool there is no way to tell
what the ACCM is telling or not telling the PCM. Either of those
modules being defective is just as likely as anything else. But whether
or not the compressor stops on it's own (dies) or is disabled
(turned-off) by the relay can be checked the same way you did on a car
in the 1980's. (hint: test-light)

Wiring a push-button will likely just ruin the thing worse than it
already is. Even in the 1980's you needed the hi and low cut-off
switches working.

GW

Ivan Vegvary > wrote:
>2008 Kia Rondo, 2.7 liter engine.
>AC cools for 8-10 minutes and then warm air for the next 5-10 minutes. Thi=
>s action continues on and on.

So the system is working properly, but then something gets out of range, and
it shuts the system down.

>Please note that this car has an s..load of sensors that may or may not tri=
>gger the compressor clutch solenoid.

How many in an assload? Three? Five? Find them, put a meter on each and
watch what happens when the system shuts down.

>Took it to a mechanic (highly recommended for diagnostics)and authorized 2-=
>3 hours of work. System charge and pressures are right on target. Could n=
>ot find the problem. ($270)
>
>Took it to the Kia dealer ($150 diagnostics) and they agree that the pressu=
>res are fine, but, the compressor is weak. Can replace the compressor for =
>a mere $1,350.

The pressures either aren't fine, or a sensor is bad. Were either of these
guys able to make the system shut down? Or was it behaving for them? If
they can't get it to fail, they'll never find it.

>Way more money than what I have. Tempted to wire a push button or toggle t=
>o the relay and mechanically force the clutch to go on while driving.

There is a reason why it's shutting off and that COULD be because the pressures
are all wrong. Maybe the evaporator is icing up when it's humid. If it is
something like this, you'll damage things if you force it on.

On the other hand, if it's a bad sensor, you won't.

>Kia reminded me that the compressor itself is $800. That leaves about $500=
>=B1 for them to play with. =20

There's nothing wrong with the compressor. Not yet, anyway.

>I used to do auto air about 30 years ago when things were simpler. Still h=
>ave gages, leak detector etc. Can't believe that a weak compressor would f=
>or some reason cycle on and off, although I do realize that pressures are p=
>robably being read (sensed)on both the low and high sides of the comp.

They are, and you need to have a meter on those sensors. If the high side
switch is shutting the thing down, and at the same time the high side pressure
is fine, you have a bad switch.

The system really isn't any more complicated than it was 30 years ago, it's
just the manuals make it look that way. And there is usually a control
computer in the loop (which does nothing important and probably isn't related
to the problem, but the meter will tell you for sure).
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."