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From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: window vs RV AC
Date: Fri, 26 Sep 2003 04:00:56 -0400
Message-ID: <>

let's start a new thread...

AFAIK, there is no such thing as an RV window unit.  He's talking about a
conventional residential window unit.

Just went down that path with my new concession trailer so I can offer some

The first and maybe biggest problem is that I could not find a 120volt powered
window unit any larger than 12k btu.  RV units are commonly available in 15k
btu and sometimes larger.  12k is just barely enough for the concession
trailer but I didn't have the option of using an RV unit.

RV ACs are designed with low inrush compressors.  Window units are not.  This
has a major impact on generator usage.  The 4kw Onan in my mom's MH will not
reliably start this window unit when the weather is in the 90s.  Sometimes the
compressor starts and sometimes it doesn't.  It puts a pretty good whack on my
8kw genny I use for the trailer.  This genny starts it OK but you can really
hear it labor for a few seconds.

I really can't see any big difference in power consumption once running.  My
window unit has a little higher SEER rating than the RV AC I have but not
enough to matter.

A window unit is not designed to manage the condensate with any significant
tilt.  An RV  unit will.  If my window unit is even a degree off level with
the rear high, water runs out the front of the unit.  It's a good name brand
(Fedders) so it's not that it's cheaply made or anything.  A window unit
simply doesn't have to deal with that problem.  I've mounted mine at a fairly
steep down-angle.  It looks somewhat funny but the water drips out the back as
it is supposed to.

A window unit is not designed for continuous vibration.  I've seen instances
where the constant vibration from travel caused the internal plumbing inside
the can of the hermetic compressor to fatigue and fail.  An RV compressor is
designed for that kind of service.

For equal cooling capacity the prices are not that much different.  New, this
unit I have was around $350.  Add another hundred plus some careful shopping
and you have yourself an RV AC.


On Thu, 25 Sep 2003 17:36:37 -0600, mts <mts@ren-prod-inc.comNOSPAM> wrote:

>"Bob  Thomas" <> wrote:
>>If your Tioga is so old, why pop 6 to 8 hundred bucks for an RV A/C when you
>>can hang a window unit on it for maybe 100 to 150??  In addition, the window
>>unit will use far less electricity??
>Good question... I really know nothing about window units for RVs and
>wasn't aware of their existence.  Any good places or search keywords
>to learn more about RV window units?

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: window vs RV AC
Date: Fri, 26 Sep 2003 13:14:51 -0400
Message-ID: <>

On Fri, 26 Sep 2003 09:25:01 -0600, mts <mts@ren-prod-inc.comNOSPAM> wrote:

>Saw a portable air conditioner, not sure where I could put the thing
>because of its size, either when in use or not in use, and it was over
>$300 which makes it silly to consider when a good rooftop unit can be
>had for well under $700 and might actually do the job decently.

FWIW, I have a couple of the GE portable units.  One I use to spot cool my
dishwasher dude so that I don't have to AC the whole washroom.  The other I
use to spot cool me in the bed at night so I don't have to cool the whole

They work good for those purposes but they're not so hot for general air
conditioning.  The problem is, while the hot condenser exhaust air is
discharged through a hose to the outside, the condenser cooling air is taken
from the room.  IOW, the unit is pumping out cold air just about as fast as it
is making it.  If the unit had two hoses, one for condenser inlet and the
other for condenser outlet, it would be a GREAT idea.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Honda 3000is vs Yahama 3000seb OR Neither
Date: Mon, 26 Jul 2004 16:12:21 -0400
Message-ID: <>

I've never seen an RV package unit (rooftop type) with a short cycle timer.
There really isn't a need.  RV AC compressors are different from ordinary AC
compressors.  The compressor general replacement catalogs have special
listings for RV compressors.  They're designed to run on a wide voltage range
and quality of power and to start reliably even on low voltage.  This design
feature makes the motor develop enough torque to start reliably on a short
cycle under most conditions.

The only time I've seen a compressor fail to short cycle start was when the
power supply was soft - too much resistance in the shore power circuit or on a
generator not capable of supplying the surge.

My 4kw inverter generator will reliably short cycle my AC until the outside
temperature rises above 95.  Then it requires a minute's rest.  Pretty much
the same situation with my mom's MH.

I wouldn't recommend short cycling an AC as a routine matter but I'd not get
excited when it happened either.


On Sun, 25 Jul 2004 10:00:02 -0700, wrote:

>On Sun, 25 Jul 2004 03:59:19 GMT, "FMB" <> wrote:
>>Thomas Allemani" <> wrote in message
>>> Come ON guys an oil change in a small engine costs about what--$2.50?
>>> filter? a couple bucks sheeze its amazing the warrantee these things
>>> at all. Anyway I went and bought a EU 3000is and tried it out today.
>>> It will run my 13,500 ac unit if I leave it cycle normaly BUT If i
>>> turn up the thermostat to kick it off then right back on the gen will
>>> disengage and the red light will come on for overload. I guess the
>>> answer to that is don't do that.
>>If your AC isn't protected from restarting too soon after shutting down, it
>>will kick a lot of generators off and may also do damage to your AC.  The
>>thermostat (or AC) has a 3 min timer which starts after the AC cycles off,
>>and it won't alow the AC to cycle back on till the 3 min are up.  Has
>>something to do with the compressor trying to compress liquid.... Some HVAC
>>fellow might come on here to explain that to you, as that is not my
>To prevent the compressor from trying to start under load, there is
>normally a delay timer to allow the pressures to equalize. Most A/C
>units use a "delay on make" timer which means that the timer starts
>when the switch is turned on. I changed mine to a "delay on break"
>which means the timer starts when power is turned off, allowing the
>compressor to start when cooling is called for the next time without
>having to wait for the delay cycle.

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: AC and genset question for small trailer
Date: Wed, 11 Jul 2007 13:56:24 -0400
Message-ID: <>

On Wed, 11 Jul 2007 09:04:44 -0700, JC Dill <> wrote:

>>A Honda eu2000 will run an 8000 btu air conditioner. It runs my 15k Coleman
>>with nothing else drawing it down...if I leave the eco-throttle switch off.
>Thanks.  I'll let her know, and pass on your insulation suggestion.

One word of caution.  If she's thinking about a window unit, tell her to test the
unit after un-boxing and before she installs it. She'll want to be able to return it
if the generator won't start it. Cover the condenser with a blanket with the unit
running to simulate blazing sun in the summer, run it awhile, turn it off, wait
awhile and try to start it with the EU.

Reason I mention this is that RV ACs contain special low starting inrush compressors
to enable them to start on generators.  Window units don't.  A small window unit can
draw as much starting current as the biggest RV unit.

I have a cheap 13.5Kbtu window unit in my concession stand.  It occasionally makes my
5KW Generac QuietPack grunt.  The AC starts but one can hear the generator work.  I'm
fairly confident that even the EU3000 would not start this AC.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Lazy I
Date: Sun, 03 Aug 2008 18:00:45 -0400
Message-ID: <>

On Sun, 03 Aug 2008 13:39:40 -0500, Bob Giddings <> wrote:

>>Somebody was BSing you on that.  R12 is now plentiful.  Lots of recycled
>>supply and little demand. The price is now almost all tax. Last time I bought
>>a blow-off can, it was about $20.  Couple of years ago.
>I was talking to a mechanic at a garage.  I'd guess he was
>telling me what they'd charge me.  I'm sure there is a wholesale
>supply to be had a lot cheaper.

I just buy blow-off cans over the counter at Napa or Auto-zombie, whichever
one has 'em in stock at the time.

I would NOT take this kind of work to a general mechanic.  Look around and
find your town's mobile AC garage.  Seems like every town has one.  Usually
the shop does radiator repairs too.  They usually do a lot of semi and reefer
work too.  Even the nearby podunk town of Madisonville here has one.

They specialize in the work, buy the parts wholesale in case lots and have the
crimping machines necessary to make up hoses.  I didn't get any special prices
at the one I used in Cleveland.  I didn't even like the guy - advanced
alcoholic.  But he had by far the lowest prices for making up hoses and
related tasks of anyone in town.

>I'd heard they didn't work well.  But the mechanic told me "that
>depends on who's doing it."  As though there were some kind of
>art to it.  I don't know what to make of that, and we didn't go
>further into it.

The early kits didn't work well.  The PAG oil decomposed quickly in the
presence of chloride residue from the R12.  Compressor failure followed.

A proper retrofit consisted of barrier hoses, O-ring replacement, a new
dryer/receiver, draining the oil from the compressor, solvent flushing the
condenser and evaporator, replacing the flare fittings with the new SAE quick
couples, filling the compressor with PAG "oil" (first cousin to brake fluid),
evacuating and then charging the system with 134a.

That's still the best way to do it and is the way I do it whenever the
customer will allow it.  My labor rates are cheap because I enjoy this work
and I like to be selective.  Still, the retrofit costs >$500.

Nowadays with the improved POE (ester) oil and additives, the process and kit
are simple  Here's  a typical kit

Here's a good page describing the different procedures

>>I didn't see anything in the litany to get excited about other than the
>>'fridge and maybe the roof.  The fridge may start cooling after a few days. It
>>took mine that long to come back to life after having sat for a couple of
>There's that much of a lag?  I asked the guy to leave it plugged
>in and tell me if it got to working.  That was yesterday, and I
>haven't heard from him.

Not normally, but if it's been sitting for while then maybe.  Mine did.  I was
just about to declare it dead when it suddenly started working.

Another factor may be trying to fire it up on 120 volts instead of AC.  The
BTU input from the gas burner was much greater than the electric heating
element.  It would start on AC but just barely.

>>If not, then you could replace it or have it rebuilt, though I'd advise not.
>>I'd never go back to absorption after having had my conventional fridge that
>>runs from an inverter.  The shelf layout is nicer than anything I've seen in
>>an absorption, it cools instantly when turned on, hot weather doesn't affect
>>it and it keeps ice cream nice and hard.
>Fact is, John, I haven't had any trouble at all with my 2000
>Dometic RM2652.  Keeps beer cold and ice cream hard.  Has to be
>defrosted once a year or so.

Mom's eh, whatever brand didn't keep ice cream hard at all.  It also didn't
keep frozen food cold enough to avoid quick freezer burn.  It was either a '99
or '01 model.  I remember that it was one year away from Y2K but I can't
recall which side.

>I have a theory that the key to absorption fridges is to keep
>them running.  Mine has never been turned off, except for
>cleaning, since I bought it.  Either on gas or electric, it just
>keeps on working like new.

I agree.  Mine stayed on practically continuously until the day that I got the
blast of gas from the thing when I opened the door.  There was an outfit in
Atlanta that would have rebuilt it for $500 but frankly, I was fed up with its
erratic performance, especially after seeing similar performance with Mom's
and some of the rigs that I've worked on.  An electric + inverter + more
battery capacity is soooo much nicer.

>I really like the inside and the comfort, and I like the way it
>drives.  I don't like the AC not working, and the fridge.
>Everything else I'd eventually learn how to fix.

The dash AC just isn't a big deal.  Really.  The 'fridge could be.  If you
have to replace it with another absorption unit, is the rig still a good value
at +$1200?  Probably.

>The other thing is the wind noise whistle above 60.  That's a
>little irritating.  I suppose the only answer to that is crank up
>the radio.  If only it worked.

Or find the whistle.  On both mine and Mom's rig, the stainless steel whip
radio antenna initially whistled.  It resonated in the wind.  I solved the
problem in both cases by slipping a length of black heat shrink onto the shaft
and shrinking it in place.  The plastic damped the stiff wire enough that it
no longer whistled.

>There is something I don't understand.  On the underside of the
>overhand are a couple of small backward facing factory vents,
>maybe a half inch high by 4 inches wide.  What the heck?
>Ventilation of the overhang?  To keep any leaks from causing

Or to keep out mildew from moisture that would condense under there in hot
humid weather when the AC is cranking.  I've never seen vents there so that's
just a SWAG.  OTOH, I HAVE seen a LOT of overhang rot so maybe they're heading
off that problem.

>This unit has not actually come up for sale yet, and he seemed
>pretty embarrassed by all the problems.  Maybe I oughta tell him
>to get the thing driveable (fix the starter and get it inspected)
>and I'd take the thing off his hands for $3K.  Blue book is
>$4843.  That would give me a little cushion.

Sounds like a plan.

>There's nothing like a lot of problems to get you up and going in
>the morning.  With this thing in the driveway I'd probably live
>forever.  :o)



From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Lazy I
Date: Sun, 03 Aug 2008 21:09:52 -0400
Message-ID: <>

On Sun, 03 Aug 2008 16:10:06 -0500, Bob Giddings <> wrote:

>On Sun, 03 Aug 2008 13:57:03 -0400, Neon John <>
>>I didn't see anything in the litany to get excited about other than the
>>'fridge and maybe the roof.  The fridge may start cooling after a few days. It
>>took mine that long to come back to life after having sat for a couple of
>Okay, John.  I heard from the Lazy Daze front.
>1. The fridge is working.  Took 24 hours to get cold.
>Is that likely due to insufficient charge?  What would cause that
>delay?  Or are there too many suspects to name just the one?

Not a charge problem.  The thing's pressurized to something like 600 psi and
then welded shut.  Either the fill gases are there or they aren't.

I'd lay the blame on two things.  One, it being laid up for awhile and two,
trying to fire it off on AC.  If he'd lit the propane it would probably have
been cooling by the time you got there.

>2.  This guy has a source for R12, somebody who tanked up on
>several cases back when it was legal.  He's going to pressurize
>the system this afternoon and see if he can get cold air.  If he
>can, even if it still has a leak, that'll tell me the compressor
>is all right, and the system CAN be fixed without replacing
>everything.  Just pressurize with dye to find and fix the leak. I
>may try just tightening all the hoses to begin with.  A top up
>may last quite a while.  I used to have a truck that needed
>topping up once a year.  Of course, back then it was a couple
>bucks a can.

OK.  With a rig that old, it's probable that some of the refrigerant loss is
diffusion through the hoses.  On old vehicles like that, more often than not,
I can wrap a plastic bag around a length of suction hose, let it sit for a
little while and then stick my H-10 leak detector nozzle in the bag and detect
freon.  The H-10 can detect a leak equivalent to 1/4 oz per year so it's
literally sniffing molecules.

The Barrier hose that I mentioned solves the problem.  It has an impervious
layer that stops R12 and 134a in its tracks.  That's the main component in
making a charge of R12 a lifetime charge.

>I also heard about something called "Freeze One" which is
>compatible with R12, works as well as R12, but is not on the
>prohibited list.  Have to look into that.

If you want a completely drop-in replacement that requires no other changes,
look at R-406a.  That's the blend that George Goble and I worked on for
several years back in the early 90's and that he got a patent on.  In addition
to being compatible with all mobile refrigeration materials, it actually
improves the average system's performance by about 20%.  The 3-component blend
can be varied to get even greater performance but we decided that 20% was a
safe value that wouldn't overload existing condensers.

A main component of the patent is using a component (propane in our case)
strictly for oil transport.  The fluorinated hydrocarbons such as R134a are
not miscible with mineral oil.  A system charged with the stuff will work fine
until all the oil ends up in the condenser or accumulator and the compressor
locks up from oil starvation.

There have been a number of attempts to skirt our patent and a few resulting
suits but in general, if a blend uses a component, the major purpose of which
is to transport mineral oil then it violates the patent.

There are two major types of drop-in refrigerants other than R-406a.  One type
is a blend of HFCs and sometimes R22 that skirt our patent but still transport
a little oil, usually by simple gas friction with the oil.  These products
work OK in some vehicles where all the components are on about the same level.
Disaster in vehicles where the compressor is at or near the highest point in
the system or where the suction line is oversized (Old GM system - not enough
gas velocity to drag the oil along.)

The other type are HC blends, propane/isobutane being the most popular mix.
George and I perfected a blend in the late 80s that worked great and we
published the formula on the net. (look in the archives from
that era for my ID, and george's,, I think)

Long story short, MACS (mobile air conditioning society) and a few others,
seeing their predicted $1200 per car retrofit profits threatened, stirred up
enough sh*t over the stuff being flammable that HC blends were outright banned
for mobile use in about 15 states.

There are still some HC blends on the market.  The way they get around the
bans is by marketing and labeling it for only stationary refrigeration use.

I don't recall which class Freeze One falls into.  Regardless, you'll have a
continuing problem with "slow leaks" until you install barrier hoses.

HC blends go through old, non-barrier hose like a dose of salts.  So does one
component of R-406a.  In the case of HCs, the diffusion is VERY fast, such as
in a month or two.  Worse, it'll sometimes loosen hunks of oxidized hose liner
and that will circulate until it either blocks one of the various screens or
bursts the desiccant sack in the receiver/dryer.  Then you have a mess on your

R12 is a large molecule and ironically, diffuses slower than any of the
replacement refrigerants.  A charge should last a whole air conditioning

I don't know if it is still on the market or not and can't recall the name but
there was/is a product designed to seal old hoses.  It consisted of two
organo-silicon compounds.  One absorbed moisture and became silicone oil.  The
other is a very thin moisture-cured RTV monomer.  After the receiver/dryer is
changed out to get rid of the moist desiccant, this stuff was charged into the
system just like oil.  The moisture absorbing component bound up any remaining
traces of moisture.  The RTV monomer diffused through the hose pores and when
it got close enough to the outside world to absorb moisture, cured into a
non-permeable silicone rubber.

This stuff worked great.  The only problem was that customers would not follow
directions.  Duh!  They'd not go to the trouble to change out the
receiver/dryer and would not hold a high vacuum on the system overnight to
remove the moisture absorbed in the pores of the inner surface of the hoses.
The result was that the stuff hit the receiver/dryer, cured on contact with
the desiccant and did nothing to seal the hoses.  And in some cases, it shed
RTV particles that stopped up the expansion device's screen.

If the stuff's still on the market then a shot of it, a new receiver/dryer and
a recharge of R12 will do ya.  If you're interested in that route, I'll try to
remember the name.

Here's another little secret that the green-weenies and MACS don't want you to
know.  You can make your own blend.  Make sure there is enough R12 still in
the system to transport the oil and then charge the system with 134a.  Works
like a champ.  It's against the EPA nazi's rules but hey, so is everything
else anymore.

You can get a good idea if there is enough R12 in the system by pressing the
shraeder valve on either the high or low side service port with the system
off.  If a foam of oil comes out with the refrigerant, then there is enough
R12.  If the gas is dry, or mostly so, then add some 12.

>If he can get cold air, and I buy it, I'm gonna try to get him to
>throw in a few cans of R12.  He may not have access to that much,
>but it's worth a try.  He's kind of cagey about the R12.

I don't blame him.  IN the beginning of the ban, both the EPA and MACS sent
out snitches to try to catch people.  EPA because, well, just because.  MACS
because they wanted to put the shade tree mechanics out of business.

Be aware that EPA rules say that you have to have a recovery system at hand
whenever working on an AC system.  Also be aware that EPA pays a 25,000 dollar
snitch reward.  Best to do your work inside a garage or at least with the nose
of the rig poking in your garage.  And at night, if possible.

I have a recovery system but I STILL hide my work.  I don't want to have to
deal with the EPA storm troopers after some greedy snitch drops a dime.

>How do you get yours?  I thought you had to be government
>licensed to even buy the stuff.  Reply by email if you want, to

I have all the certs and licenses.  I just show my green card and buy away.

Most anyone can get a "section 609" mobile AC certification.  It involved a 20
question open-book test and a $20 fee.  You're limited to buying refrigerants
that are used in mobile applications but that's not too much of a hardship.

IMACA used to be the major on-line license grantor.  They were formed to
oppose MACS who was trying to use the licensing requirement to eliminate both
shade-tree mechanics and general purpose mechanics from competing with their
membership.  EPA let them write the regulation.  yeah, very dirty.  Even the
name IMACA was chosen to poke at the eye of MACS.

Unfortunately they were bought out by MACS and it appears that the
domain is now gone.  Hmmm, it looks like MACS is now offering the Section 609
certification.  The procedure is a bit more complex but still fairly simple.

Looks like the fee is $15.

Other than buying an occasional can of R12, the handiest use of this cert is
buying R22 for your home AC.  It's used in mobile refrigeration systems (such
as your RV's roof-top AC) and so can be bought on a 609 card.

BTW, if you plan on keeping an R22 system going, now is the time to stock up.
Actually, it's past time.  The irrational* EPA-mandated phase-out is underway
and that is running the price up extremely rapidly.  It went up $100 per 30 lb
tank just in the last year.  I bought a couple of cylinders recently for just
in case but I've decided that all my future R22 work is going to be done with

* Even if you believe in the ozone hole myth, R22 is about as harmless as it
gets.  R12 had a claimed ODP (ozone depletion potential) of 1.0.  R22 is
something like 0.05 or some similar tiny number.  Plus 99.99% of the R22 is
used in hermetically sealed systems that are only opened to replace something
that broke.  The refrigerant is recovered in the process.  They don't leak and
they don't need topping off.

The phase-out is purely doctrinal - no rational nor scientific reason behind
it - simply a "gotta ban all chlorine-containing refrigerants just because".

>3.  He's convinced the fire problem was caused by the starter
>hanging.  He's going to replace the starter.  We'll see what
>happens then.


>4.  I've come to a few conclusions during my motorhome hunt.
>A bargain ain't a bargain unless it's what you want.
>If it's what you want, structural problems like rot,
>delamination, and leaks are next.
>If all that's okay, drive quality is the third consideration.
>After that, it's just a matter of what you feel like fixing.
>Nothing alone in the grab bag is a deal breaker, though all the
>parts together may add up to one.  That's the situation I'm in

Fully agree with that too.

I kinda enjoy fixing up my rig.  Like hotrodding, only there's a lot more room
to work in.  Once the mission-critical stuff is fixed, the rest can be
governed by your supply of round tuits :-)


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