28' 1991 Breakaway 5.9 Cummins.
Heater Core leaking, also replacing a/c compressor. Unable to access Evaporator Coil and Heater Core. Looks like they were factory installed right before the outside skin was riveted on. Any ideas?
P.S. Thanks to Hank Wadley for help in locating a/c compressor!

You can get to heater core & evaporator from the inside, front wall (by the return vent). Unfortunately, you do have to pull off some carpet and saw through the wood, but that beats going in through the front. I had the evaporator replaced in my unit, and you really can't tell that we ever went in from the cab. The picture in the ACME catalog I referenced you to shows the plenum assembly details, etc. pretty clearly. Good luck.

I'm having similiar problems on 1989 25'C Regal. I don't see how to access after tearing out the plywood I have more metal. I can run my finger over the heater core, but don't see any fasteners to unscrew.

Well, I had to go into mine again. This time I did it myself and learned a whole lot more...for example, that my repair guy never did get to it the way he told me he did...sorry for the misdirection (even sorrier about the $1600 I gave these bozos).

Here is the straight scoop in gory detail...very long post (130 lines)...

I have received many questions about gaining access to the Heater - A/C plenum box. Since this is something we all have to do sooner or later (2nd time for me) and it is a long, complicated procedure, I thought this would be a worthwhile posting. Even if you don't work on your Barth yourself, you might want to print this off to assist your repairman. Mine charged me $1600 to replace the evaporator coil. He not only did a lousey job and took 17 days to do it, but he damaged many components trying to figure out how to get to the evaporator --- such as my backup monitor --- which didn't need to be removed in the first place.

In order to get to the heater core or evaporator coil, it is necessary to remove the heater plenum (box). The following information is accurate for my 1992 BS11B Breakaway (30', front door model) with ACME
A/C; your installation may be different.

If you are putting an order together for ACME, be sure to add items for new Prestite insulating tape and adhesive backed foam...you're sure to need them. ACME can be reached at 800-552-2263 or www.acmeair.com. Be sure to get their "Catalog for Recreational
Vehicle A/Cs & Heaters".

If you have never done this before, make sure you have plenty of
coffee and band-aids available. It took me three days to get my
plenum out (included much head-scratching). Hopefully, these
directions will help and the engineering changes I'll suggest will
greatly simplify getting to the unit in the future.


REMOVING AND REPLACING HEATER PLENUM

1 Drain coolant from engine at front faucet (approx 4 gallons)
2 Remove Freon/R134a from A/C system
3 Remove front entry grab-rail (4 screws under buttons)
4 Disconnect 12V power (chassis and house)
4 Remove heater blower motor cooling tube
5 Remove & Label heater blower wires
6 Remove 5 sheet-metal screws from heater blower cover
7 Remove heater blower
8 Reach inside cavity where heater blower was; remove 5 sheet metal
screws which go into dash / backing ring
9 Remove door-restraining belt hooks (2)
10 Remove trim piece under door restraining hooks
11 Remove right-side trim piece cover vertical frame from dash to
overhead (under 3 buttons). Good idea to spray surface with
Armor-All where it meets dash and overhead to reduce rubbing
12 Remove (4) buttons/screws on dashboard cover.
13 Remove (24) screws holding defroster vents to dashboard cover
14 Remove & Label (2) ground wires / (4) hot wires for
windshield defrosting fans. Pull loosend wires through
firewall grommet
15 Remove (6) screws holding defroster fans to dashboard cover
16 Remove dashboard cover. Careful! Very flexible/flimsy. Lift up
slightly at each fan, pull wires through, remove fan. Repeat
for other side. Then pull up on right side where vertical trim
piece was. You might want an assistant to keep cover from
flexing too much...not necessary but it would help.
17 Remove all screws from two aluminum plates surrounding right
defroster vent. Cut sealer with razor slitter around all sides
except side nearest to front of windshield
18 Remove rear portion of L-shaped aluminum plate and rotate front
L-shaped plate up. Raise right side of defroster vent and push
it through dash to remove it
19 Remove A/C and plumbing connections from plenum. Remove expansion
valve and cover openings for protection.
20 Remove right front headlight assembly.
21 Remove any wire clamps, etc. which may still be in the way of
sliding the plenum toward the front grill opening for removal.
22 Get someone with VERY small hands and arms to help. Look through
hole (where defroster vent was) down and to the rear. Remove
(3) screws holding top of plenum to firewall. The one at the
right is almost impossible, but you can get it.
23 From the front of the rig, remove vacuum line to plenum vacuum
motor and remove (2) screws from bottom of plenum to firewall.
Plenum is now loose and quite heavy (although tar-sealer &
insulation may be holding it to firewall still). Rock and pull
gently back and forth. If it doesn't come off, either you or I
forgot to remove something else...look for it.
24 Reaching through the headlight cavity, lower the plenum to about
even with the bottom of the headlight opening then slide it to
the right and remove through front grille. Don't worry about
damaging the coils during this step --- they are protected by
a steel backing plate in the plenum.

To reinstall, reverse the above steps, more or less. To begin hanging
the plenum, roughly position it and then hang it by the lip of
the backing plate engaging the cut-out for the return air in
the firewall.

While you have your Barth completely disassembled and your
spouse is screaming that it will never look the same again, I
would suggest the following engineering changes to greatly
simplify doing this again in the future:

1 Obtain (3) 1/4-20 T-Nuts
(3) 1/4-20 hex-headed machine screws or bolts, approx
1-1/4" long
(9) 4-40 machine screws, 1/2" long, washers and nuts
2 Drill 1/4" holes in plenum where the top three sheet-metal
screws were. Install T-nuts in these holes, and secure with (3)
4-40 screws each. Be sure the "top of the T" is outside the
plenum with the threaded portion going through (facing the rear
of the coach when installed).
3 Drill corresponding 1/4" holes (actually a tad larger for
installation ease - to allow for plenum flexing) through
firewall.
4 Reinstall the plenum as above, but now pass the three top bolts
through from the inside of the coach engaging the T-nuts.

Now, the top three bolts can be removed in the future from the
inside without removing all that dashboard stuff. All you have
to do is get your small-handed friend to reach in from under the
dash for the right one. It's tough, but possible. If a little
bit more room would help, remove the bottom sheet-metal screw
holding the dash front to the frame and you can flex it out a
bit with no ill effects.

The center one is easy to get from inside the heater motor
cavity.

The left one, depending on the dexterity of your friend can be
gotten from below, or you can remove the two screws holding the
right-most A/C vent into the dash, detach the hose from the vent
and gain access through the hole for the removed vent.


I sincerely hope you never have to go through this exercise but,
if you do, I am sure these instructions will help a lot. Any
comments, corrections, suggestions or updates regarding your
particular coach or experience are welcomed!

Hank Wadley

I've just completed my second heater plenum removal/replacement...this time I did it myself. Found out my repairman lied to me...he didn't get in that way, he just told me he did to justify some of the damage he did. I apologize for spreading this misinformation, but I never doubted him before.

I've put together a fairly complete set of instructions which are the result of my having done it myself...so I know it's accurate. I'll post it as a separate item in a minute. Comments/corrections are appreciated!