I'll do a little research and see what I can find out. Many of the A-6s had
a bung on the side to 'check' the oil level. Strange, huh?
I used to have a whole library of info on these babies. We lost our home to
a fire in '82 and with it a lot of very good info. (Along with almost
everything else we owned). I'll have to see what's still around, but I don't
think I've got the vast library that I once had.
I just don't remember if they threw oil out the discharge because of the
design or in response to liquid coming in the suction side as they started
up. I do remember that they keep a lot of oil in circulation when running,
and that oil slugging in the expansion valve was a fairly common problem.
My other concern with a hermetic (at least most of them) is their
intolerance of low voltage during startup and their tendency to carbonize
(and thus contaminate) the whole darn system when they blow a winding.
Campgrounds are notorious for low voltages, and that doesn't mix well with
sealed compressors. They also suspend the motor/compressor internally with
undampend coil springs, and use flexible coils to connect to the outside
world through the case. That might introduce an interesting service life
dynamic, even as smooth as our coaches ride. If you've ever dropped a
hermetic and broken a motor mount, you know what I mean.
I do agree with your point that hermetic are quiet and reliable. I've just
can't recall seeing one on a refrigerated trailer, ice truck or other moving
vehicle. Again, just thinking out loud.
Mark
> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of Travis Martin
> Sent: Friday, April 23, 1999 11:21 PM
> To: gmcmotorhome
> Subject: Re: GMC: Rear evap issues (was: A.C. compressor)
>
>
> Mark,
>
> Sounds like a viable plan to me. I guess if you didn't get a suburban for
> your research i don't need to ask for one...I'd settle for a 98 as long as
> it was black or red. Or maybe white.
>
> I wonder where a guy could get an overrunning clutch that would fit neatly
> inside the motor sheave? Surely that isn't too big a chore. If you've
> followed Arch and my discussion, you'll see that we don't agree on why but
> we do agree on the need for it...
>
> But the separate compressor idea solves that problem. How serious to you
> think the oil distribution problem to be? Is there a way to minimize the
> A-6's proclivity for spewing its oil? A trap perhaps?
>
> A hermetic would have a lot of advantages.
>
> Travis
>
> -----Original Message-----
> From: Mark Grady
> To: gmcmotorhome
> Date: Friday, April 23, 1999 11:14 PM
> Subject: GMC: Rear evap issues (was: A.C. compressor)
>
>
> >
> >> Arch, I just had another thought (!!!)
> >>
> >> If the rear evaporator (s) are using expansion valves, which is
> >> the case if
> >> we use the units from suburbans etc, then we need the compressor
> >> to run all
> >> the time. This will mean installing an expansion valve and POA
> >> valve on the
> >> front evaporator. Or do we nead a POA? Mark?
> >>
> >> But it means we don't have to worry about cycling the
> compressor and so a
> >> clutch on the electric motor is back to being unnecessary.
> >>
> >> Or that's the current state of my cortexical flatulence.
> >
> >A POA *would* be a choice for a full run compressor.
> >
> >I'd lean more toward a solenoid in the liquid line and a conventional
> >thermostatic expansion valve if the Suburban rear evaps use one. The NAPA
> >temp catalog used to have all sorts of stuff like this, but I haven't
> looked
> >at one for a while. I'll try and get a copy tomorrow.
> >
> >Unless you're really spinning the compressor, I doubt that you'd
> freeze up
> >three evaps unless the air flow is low, temp is low and humidity is high.
> >Basically, that would be spring and fall in Indiana.
> >
> >POA valves are big (physically). They also aren't calibrated for
> 134, which
> >likes lower low side pressure than R-12. That's the down side.
> >
> >Individual capillary tube thermostats controlling the high side
> liquid flow
> >expansion valve would be my first choice. The last therm to turn
> off would
> >stop the compressor. Very simple to implement, individual temp control is
> >possible, works regardless of compressor speed, etc. The question is
> whether
> >these solenoids are still available. The electrical logic would be very
> >simple to implement.
> >
> >Again, this is theory, but I do see a good idea jelling up. I
> had a funeral
> >viewing today that kept me from making time to get to Acme Air. Perhaps
> >Monday. I never like to settle on an idea till I know what's out there to
> >pick from.
> >
> >I mentioned at work today that I'd like to requisition a '99 Suburban for
> >"research." Accounting dept looked over the half glasses, tugged down the
> >green eyeshade and froze the coffee in my cup with a mean stare.
> >
> >Also, I'll offer that we could schedule a call sometime next week (maybe
> >Thursday?) to discuss this topic on the phone. Let me know if you're
> >interested and I'll send you conference bridge instructions. Just a
> thought.
> >We can report back on our development ideas so anyone who's
> interested can
> >follow along.
> >
> >Mark
> >
> >
>
a bung on the side to 'check' the oil level. Strange, huh?
I used to have a whole library of info on these babies. We lost our home to
a fire in '82 and with it a lot of very good info. (Along with almost
everything else we owned). I'll have to see what's still around, but I don't
think I've got the vast library that I once had.
I just don't remember if they threw oil out the discharge because of the
design or in response to liquid coming in the suction side as they started
up. I do remember that they keep a lot of oil in circulation when running,
and that oil slugging in the expansion valve was a fairly common problem.
My other concern with a hermetic (at least most of them) is their
intolerance of low voltage during startup and their tendency to carbonize
(and thus contaminate) the whole darn system when they blow a winding.
Campgrounds are notorious for low voltages, and that doesn't mix well with
sealed compressors. They also suspend the motor/compressor internally with
undampend coil springs, and use flexible coils to connect to the outside
world through the case. That might introduce an interesting service life
dynamic, even as smooth as our coaches ride. If you've ever dropped a
hermetic and broken a motor mount, you know what I mean.
I do agree with your point that hermetic are quiet and reliable. I've just
can't recall seeing one on a refrigerated trailer, ice truck or other moving
vehicle. Again, just thinking out loud.
Mark
> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of Travis Martin> Sent: Friday, April 23, 1999 11:21 PM
> To: gmcmotorhome
> Subject: Re: GMC: Rear evap issues (was: A.C. compressor)
>
>
> Mark,
>
> Sounds like a viable plan to me. I guess if you didn't get a suburban for
> your research i don't need to ask for one...I'd settle for a 98 as long as
> it was black or red. Or maybe white.
>
> I wonder where a guy could get an overrunning clutch that would fit neatly
> inside the motor sheave? Surely that isn't too big a chore. If you've
> followed Arch and my discussion, you'll see that we don't agree on why but
> we do agree on the need for it...
>
> But the separate compressor idea solves that problem. How serious to you
> think the oil distribution problem to be? Is there a way to minimize the
> A-6's proclivity for spewing its oil? A trap perhaps?
>
> A hermetic would have a lot of advantages.
>
> Travis
>
> -----Original Message-----
> From: Mark Grady
> To: gmcmotorhome
> Date: Friday, April 23, 1999 11:14 PM
> Subject: GMC: Rear evap issues (was: A.C. compressor)
>
>
> >
> >> Arch, I just had another thought (!!!)
> >>
> >> If the rear evaporator (s) are using expansion valves, which is
> >> the case if
> >> we use the units from suburbans etc, then we need the compressor
> >> to run all
> >> the time. This will mean installing an expansion valve and POA
> >> valve on the
> >> front evaporator. Or do we nead a POA? Mark?
> >>
> >> But it means we don't have to worry about cycling the
> compressor and so a
> >> clutch on the electric motor is back to being unnecessary.
> >>
> >> Or that's the current state of my cortexical flatulence.
> >
> >A POA *would* be a choice for a full run compressor.
> >
> >I'd lean more toward a solenoid in the liquid line and a conventional
> >thermostatic expansion valve if the Suburban rear evaps use one. The NAPA
> >temp catalog used to have all sorts of stuff like this, but I haven't
> looked
> >at one for a while. I'll try and get a copy tomorrow.
> >
> >Unless you're really spinning the compressor, I doubt that you'd
> freeze up
> >three evaps unless the air flow is low, temp is low and humidity is high.
> >Basically, that would be spring and fall in Indiana.
> >
> >POA valves are big (physically). They also aren't calibrated for
> 134, which
> >likes lower low side pressure than R-12. That's the down side.
> >
> >Individual capillary tube thermostats controlling the high side
> liquid flow
> >expansion valve would be my first choice. The last therm to turn
> off would
> >stop the compressor. Very simple to implement, individual temp control is
> >possible, works regardless of compressor speed, etc. The question is
> whether
> >these solenoids are still available. The electrical logic would be very
> >simple to implement.
> >
> >Again, this is theory, but I do see a good idea jelling up. I
> had a funeral
> >viewing today that kept me from making time to get to Acme Air. Perhaps
> >Monday. I never like to settle on an idea till I know what's out there to
> >pick from.
> >
> >I mentioned at work today that I'd like to requisition a '99 Suburban for
> >"research." Accounting dept looked over the half glasses, tugged down the
> >green eyeshade and froze the coffee in my cup with a mean stare.
> >
> >Also, I'll offer that we could schedule a call sometime next week (maybe
> >Thursday?) to discuss this topic on the phone. Let me know if you're
> >interested and I'll send you conference bridge instructions. Just a
> thought.
> >We can report back on our development ideas so anyone who's
> interested can
> >follow along.
> >
> >Mark
> >
> >
>
