Chassis A/C

[randydupree2000]

---ok,so now get a test light and check to see if you have power to
the low pressure switch,if so,and the power is not going through the
switch you have either a bad switch,or no freon in the system.
randy In WanderlodgeForum@yahoogroups.com, David Brady
wrote:
>
> Thanks for the suggestion Randy, but no go on the wiggle.
> I'll be visition Josam's in Orlando on Monday, maybe they
> can have a look at it.
>
> David
> '02 LXi, Smokey, Va
>
> randydupree wrote:
>
> >if you wiggle the wires on the low pressure switch on the
compressor does it
> >make it work? i have to do this alot on the GM cars we have. with
the ac
> >turned on,engine running,wiggle the wires on the comp. and on the
hoses..
> >randy
> >----- Original Message -----
> >From: "David Brady"
> >To:
> >Sent: Saturday, March 04, 2006 2:56 PM
> >Subject: Re: [Wanderlodge_all] Re: Chassis A/C
> >
> >
> >
> >
> >>Before an after a 100 mile drive I checked to see if the
compressor
> >>was clutching-up and it wasn't. Does anyone know what kind of
> >>circuit breakers or fuses are in the compressor control path? a
> >>schematic would be very useful. I have a decent set of tools with
> >>me so any suggestions for diagnosing are greatly appreciated.
> >>
> >>Thanks again,
> >>David Brady
> >>'02 LXi, Smokey, Va
> >>
> >>Gregory OConnor wrote:
> >>
> >>
> >>
> >>>David, does the engine fan clutch up? did you try this with the
> >>>engine running and warm and the interior thermostat set lower
than
> >>>interior temp? some systems will not clutch up during startup
of the
> >>>vehicle. I have a 92 cummings M14 in a truck that stores
codes for
> >>>the ac functions. Having the computer read reveals volumns.
> >>>Greg--- In Wanderlodge_all@yahoogroups.com, David Brady

> >>>wrote:
> >>>
> >>>
> >>>
> >>>
> >>>>Folks,
> >>>>
> >>>>My chassis air conditioning isn't working. I haven't
> >>>>found any blown fuses or circuit breakers. The control
> >>>>switch wiring looks okay. If I turn on the key and toggle
> >>>>the dash ac switch I don't see any voltage changes on the
> >>>>wires going to the compressor (in the engine compartment),
> >>>>nor do I hear any relay chatter. The compressor doesn't
> >>>>seem to be engaging. Any ideas on what I can check?
> >>>>
> >>>>Thanks,
> >>>>David Brady
> >>>>'02 LXi, Smokey, Va
> >>>>
> >>>>
> >>>>--
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3/3/2006
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> Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date:
3/3/2006
>

[David Brady]

Thanks Randy, I'll try that in the morning. I could use a
lesson on the theory of operation. You mention the low
pressure switch. Without getting into the heat pump stuff
of compressing gas and letting it expand at a lower pressure
and consequently creating a cooling effect, which I basically
understand, what's in the control path that makes this
system work? What does the low pressure switch do? Are
there other sensors/switches? AFAIK, the system does
not use a thermostat; ie, it's either on or off. I guess she
compresses until the low pressure switch turns her off and
then when low pressure is hit again, the compressor
engages. There may be some hysteresis in here too. So
when I press the blue a/c switch on the dash, what does
that do?

Thanks,
David Brady
'02 LXi, Smokey, Va

randydupree2000 wrote:

>---ok,so now get a test light and check to see if you have power to
>the low pressure switch,if so,and the power is not going through the
>switch you have either a bad switch,or no freon in the system.
>randy In WanderlodgeForum@yahoogroups.com, David Brady
>wrote:
>
>



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Checked by AVG Free Edition.
Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date: 3/3/2006

[putneyflash@...]

you can jump across the contacts for the switch if compressor comes on ok, but
that doesn/t mean the switch is bad if you lose freon the low pressure switch
shiuts off the compressor,

-------------- Original message from David Brady :
--------------

Thanks Randy, I'll try that in the morning. I could use a
lesson on the theory of operation. You mention the low
pressure switch. Without getting into the heat pump stuff
of compressing gas and letting it expand at a lower pressure
and consequently creating a cooling effect, which I basically
understand, what's in the control path that makes this
system work? What does the low pressure switch do? Are
there other sensors/switches? AFAIK, the system does
not use a thermostat; ie, it's either on or off. I guess she
compresses until the low pressure switch turns her off and
then when low pressure is hit again, the compressor
engages. There may be some hysteresis in here too. So
when I press the blue a/c switch on the dash, what does
that do?

Thanks,
David Brady
'02 LXi, Smokey, Va

randydupree2000 wrote:

>---ok,so now get a test light and check to see if you have power to
>the low pressure switch,if so,and the power is not going through the
>switch you have either a bad switch,or no freon in the system.
>randy In WanderlodgeForum@yahoogroups.com, David Brady
>wrote:
>
>



--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date: 3/3/2006



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[Gregory OConnor]

Randy, does the engine fan kick on when you ask for AC at the dash or
does the Low Pressure Switch turn the fan on ?
Greg
--- In WanderlodgeForum@yahoogroups.com, "randydupree2000"
wrote:
>
> ---ok,so now get a test light and check to see if you have power to
> the low pressure switch,if so,and the power is not going through
the
> switch you have either a bad switch,or no freon in the system.
> randy In WanderlodgeForum@yahoogroups.com, David Brady
> wrote:
> >
> > Thanks for the suggestion Randy, but no go on the wiggle.
> > I'll be visition Josam's in Orlando on Monday, maybe they
> > can have a look at it.
> >
> > David
> > '02 LXi, Smokey, Va
> >
> > randydupree wrote:
> >
> > >if you wiggle the wires on the low pressure switch on the
> compressor does it
> > >make it work? i have to do this alot on the GM cars we have.
with
> the ac
> > >turned on,engine running,wiggle the wires on the comp. and on
the
> hoses..
> > >randy
> > >----- Original Message -----
> > >From: "David Brady"
> > >To:
> > >Sent: Saturday, March 04, 2006 2:56 PM
> > >Subject: Re: [Wanderlodge_all] Re: Chassis A/C
> > >
> > >
> > >
> > >
> > >>Before an after a 100 mile drive I checked to see if the
> compressor
> > >>was clutching-up and it wasn't. Does anyone know what kind of
> > >>circuit breakers or fuses are in the compressor control path? a
> > >>schematic would be very useful. I have a decent set of tools
with
> > >>me so any suggestions for diagnosing are greatly appreciated.
> > >>
> > >>Thanks again,
> > >>David Brady
> > >>'02 LXi, Smokey, Va
> > >>
> > >>Gregory OConnor wrote:
> > >>
> > >>
> > >>
> > >>>David, does the engine fan clutch up? did you try this with the
> > >>>engine running and warm and the interior thermostat set lower
> than
> > >>>interior temp? some systems will not clutch up during startup
> of the
> > >>>vehicle. I have a 92 cummings M14 in a truck that stores
> codes for
> > >>>the ac functions. Having the computer read reveals volumns.
> > >>>Greg--- In Wanderlodge_all@yahoogroups.com, David Brady
>
> > >>>wrote:
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>>Folks,
> > >>>>
> > >>>>My chassis air conditioning isn't working. I haven't
> > >>>>found any blown fuses or circuit breakers. The control
> > >>>>switch wiring looks okay. If I turn on the key and toggle
> > >>>>the dash ac switch I don't see any voltage changes on the
> > >>>>wires going to the compressor (in the engine compartment),
> > >>>>nor do I hear any relay chatter. The compressor doesn't
> > >>>>seem to be engaging. Any ideas on what I can check?
> > >>>>
> > >>>>Thanks,
> > >>>>David Brady
> > >>>>'02 LXi, Smokey, Va
> > >>>>
> > >>>>
> > >>>>--
> > >>>>No virus found in this outgoing message.
> > >>>>Checked by AVG Free Edition.
> > >>>>Version: 7.1.375 / Virus Database: 268.1.1/272 - Release Date:
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>3/1/2006
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>Yahoo! Groups Links
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>
> > >>--
> > >>No virus found in this outgoing message.
> > >>Checked by AVG Free Edition.
> > >>Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date:
> 3/3/2006
> > >>
> > >>
> > >>
> > >>
> > >>Yahoo! Groups Links
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >
> > >
> > >
> > >
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> > --
> > No virus found in this outgoing message.
> > Checked by AVG Free Edition.
> > Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date:
> 3/3/2006
> >
>

[David Brady]

Hi George,

Thanks for your help. I tried your diagnostics and found
that the clutch internal resistance is good, but the 12v
supply from the harness is non-existent. I may have a
fuse or circuit breaker issue, but I can't find a fuse/circuit
breaker at any of my load centers that's labeled anything
close to chassis a/c. Ralph, I looked in the outside
compartment next to the pilot seat, but there are no
fuses there for the chassis a/c that I can tell. Any help
in finding fuses is greatly appreciated.

Thanks,
David Brady
'02 LXi, Smokey, Va


George Lowry wrote:

>David,
>
>Had a similar problem with our '95 bird. At the compressor, you should
>find a wire that goes to the clutch. Mine had a connector that I could
>unplug, If it is a butt connector, just cut the wire. Two checks.
>First; with the key in the on position and the A/C controls set for
>cooling, check the wire end that comes from the harness for 12 volts.
>If you are not getting 12 volts, you probably have a blown fuse or
>other similar problem. Second; using an ohm meter, check the wire
>going to the clutch for continuity. The clutch is internally grounded
>so you should get a very low resistance reading. If it shows infinite
>resistance, the clutch coil is open and needs to be replaced. A
>confirming test is to use a jumper wire and connect 12 volts to the
>wire to the clutch. If the clutch is ok, it will pull in. That will
>give you a starting point.
>
>George Lowry
>'06 Alpine Apex - Formerly '95 Wbda 4203
>Spearfish, SD Now in Gila Bend, AZ
>
>David Brady wrote:
>
>
>
>



--
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Checked by AVG Free Edition.
Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date: 3/3/2006