1992 WB40 Air Conditioner replacement - directions & pics
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06-23-2007, 16:29
Post: #1
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1992 WB40 Air Conditioner replacement - directions & pics
NOTE: I have two Dometic AC units that I am willing to part out
cheap to anyone needing parts. I probably could part out one of the thermostats if someone needed one badly enough (need to find a way to plug up the hole and hang something over it I replaced both front and center Dometic units with new Carrier AirV 15Kbtu Heat Pumps. I choose these units because they have infrared remote controls and the head unit is installed in the lower unit cover. So you do not have to replace the original wall thermostats as they just get disconnected and are no longer used. One thing to note about newer units, they all appear to require 12 volts now, whereas the older units installed in the BB only needed 120 volt AC and the voltage for the thermostat was generated in the AC unit and sent to the thermostat over the thermostat wiring harness. So you will need to be prepared to run a 12 volt positive and ground to the new AC units. OK lets get started: First make sure all AC power is disconnected from the unit (turn off the forward AC control switches, turn off the thermostat controls, turn off the circuit breaker, disconnect shore power, etc.). Next you will need to remove the lower panel from the unit. In a 1992 WB40, this is a vinyl wrapped piece of plywood with a air filter grate attached to it. The panel is held in place by four plastic push in retainers (see "dometic lower cover push pin_*.jpg") that are pushed into holes drilled into the ceiling plywood. The retainers are located about 1" to 2" in from each front and rear corner. You can open the filter grate and grasp the lower unit at the front with your fingers and pull down and get the forward of the unit to pop out of their holes, then grasp the panel along the sides toward the back and do the same thing. Once the lower unit cover is removed, you will need to disconnect the power lines at the lower unit (see "dometic electrical box_*.jpg"). Then remove the screws located inside the electrical box as the electrical box covers one of the retainer bolts and you can only get at it if you remove the electrical box. You can also remove the thermostat harness at this point, one side of this harness has a latch, you can see it in the picture "dometic thermostat wiring latch.jpg", press on this latch and pull the two halves apart. Next remove the lower duct diverter cover (see "dometic lower w_o cover.jpg"), believe there are about 18 phillips screws here. Once you remove these screws, if the lower unit has silicon sealer around the edges sealing it to the upper unit (see "dometic ducted assy_*.jpg") you need to score the sealer with a razor to ease the removal of the ducted assy. Once the screws are removed and the silicon scored, take a standard flat bladed screw driver and insert it between the cover and the AC unit and pry the diverter cover from the upper unit. Next you will need to remove the four retainer bolts (see "dometic ac retainer bracket and bolt_*.jpg). If you are replacing the unit with a new unit that will use a new lower unit, you will need to also remove the brackets as they are not needed with a new lower unit normally. The upper unit can now be removed. My upper unit seals where siliconed to the coach roof, so it took a bit of force to break this seal. I just grasped the rear of the AC unit as it gives you more leverage and pulled up with consistent force until the unit broke the seal. Then load the unit on a lift (I used a Genie Superlift, see "Carrier ac on genie lift_*.jpg") and lower from the coach. Or use whatever method you have to get the unit off the roof. Now is a good time to run the new 12 volt wiring harness if your unit needs one. This could be done in one of several ways. If you are not using the harness for the thermostat, you could cut off the end and twist half the wires together for the positive side and half for the ground at the AC end, and then do the same at the thermostat near the drivers seat. Then snake a new wire from the thermostat to the upper forward fuse panel and install a new fuse and the wiring. I choose to run a new wire. I did this at the center AC unit. I drilled a hole (first one was too high and ended in the foam insulation) low enough to miss the foam insulation (see "Carrier 12v wiring hole.jpg"). In my coach, the kitchen is on the street side at mid-cabin. So I removed the wiring chase in the upper kitchen cabinets and then used a fish tape to go from the hole to street side wiring chase. I found an unused circuit here which was capped. It was labeled #9, and it was also not attached at the upper front fuse panel and was capped as well. I used this wire to run my 12V positive. Next I located a wire in the chase that was grounded to the chassis in the wiring chase (you will have to ohm to find this ground (mine was white in color), or just find a chassis tubing and tap a new wire into it for the ground). I attached the wire labled #9 at both ends and added a fuse in the upper fuse panel for this circuit. Because I was also installing a new forward unit, I used the fish tape to go between the vinyl ceiling panels and the roof plywood from the center unit to the forward unit and joined these two circuits together at the new center AC unit. So the circuit goes from the upper forward fuse panel down the street side upper wiring chase, then goes at mid-coach to the center AC unit via a new hole in the center AC support bracing, it is then connected to the AC 12 volt wiring and also jumpered to the forward AC unit (goes between the ceiling panels and the plywood sheeting) and connected to the 12 volt circuit there. Next clean the opening on the coach in prep for the new unit. Get the new unit up on top of the coach (I used the Genie lift here as well, also used it to remove an old spare tire that was on my roof that was the wrong size). Lift the AC unit and place it over the opening in the roof (DO NOT SLIDE THE UNIT AS IT WILL DAMAGE THE SEAL). If you so desire, run a bead of silicon around the opening before you place the unit over the hole. Make sure the unit is centered over the hole and square on the roof and then return to the inside of the coach to finish the install. Next, if you are using the original BB brackets and lower unit run the four AC retaining bolts through the brackets (this may require that you re-position the BB brackets by removing the two wood screws from each bracket and re-attaching in the proper place). Torque these bolts to the manufacture spec. If you are using a new lower unit, follow the instructions to attach any wires or other items before the bolts are secure and then secure the bolts and torque them to specs. For the Carrier AirV, locate the new lower unit assy, before installing the assy, attach the foam block to the upper unit per the instruction (lining the one edge up with the edge of the AC air outlet) by removing the paper backing to expose the adhesive. Now attach the ducted divider to the lower unit at the correct height for you unit (mine was the very first hole for 3.25"). Now run the four long retaining bolts (see "Carrier lower unit mounting bolts.jpg") through the lower unit to the upper unit. Place the three wiring harnesses (see "Carrier lower unit wiring harness-1.jpg") that attach to the curb side of the AC unit on that side of the electrical box, and the one wiring harness (sorry no individual pic of this harness, you can see it on the right side of the electrical box in pic "Carrier test unit before final mounting.jpg") that attaches on the street side of the electrical box. Attach these harnesses to their proper connectors on the lower electrical box. Next attach the new 12 volt harnesss to the red and black wires that are located on the street side of the electircal box. There will be two blue wires with the harness that will not be used (they are used for AUX FURNANCE, which does not exists in the WB40). Next insert the freeze protect thermal sensor in the condenser at the center of the condenser. Push it all the way in at a 45 degree angle to the condenser per the instructions. Remove the two screws (one on each end) from the lower unit electrical panel (see "Carrier lower cover ac wiring cover_*.jpg") to gain access to the area where the AC wiring will be connected Insert the plastic grommet in the hole in the side of the electrical box, insert the AC wiring and then attach the romex wire to the AC Unit wiring (see "Carrier lower cover ac wiring.jpg"). The unit should be ready to run at this point, so before putting the electrical box cover back on, plug the coach shore power in, turn on the AC breaker and test the unit. If everything is OK, turn off the breaker,disconnect power, etc. and re-install the lower electrical box cover. Then install the lower unit cover (see "Carrier lower unit in operation.jpg"), turn on the power and breakers and enjoy your new AC unit. Note: If you need to remove any of your ceiling vinyl panels, they use plastic retainers similar to the AC lower cover (see "Ceiling panel push pins_*.jpg"). They are located at various places along the panel. They are a little bit of a pain to find and then get them to release, just be patient in locating and getting the to release. Michael Brundridge 1992 WB40 Georgetown, TX |
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06-23-2007, 16:31
Post: #2
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1992 WB40 Air Conditioner replacement - directions & pics
Forgot to mention in the article that the pictures are located in the
Photos section under the folder titled "Air Conditioner". Michael Brundridge 1992 WB40 Georgetown, TX |
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06-24-2007, 00:36
Post: #3
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1992 WB40 Air Conditioner replacement - directions & pics
--- In WanderlodgeForum@yahoogroups.com, "mbrund" <mbrund@...> wrote:
> > NOTE: I have two Dometic AC units that I am willing to part out > cheap to anyone needing parts. I probably could part out one of the > thermostats if someone needed one badly enough (need to find a way > to plug up the hole and hang something over it > > I replaced both front and center Dometic units with new Carrier AirV > 15Kbtu Heat Pumps. I choose these units because they have infrared > remote controls and the head unit is installed in the lower unit > cover. So you do not have to replace the original wall thermostats > as they just get disconnected and are no longer used. One thing to > note about newer units, they all appear to require 12 volts now,............ Howdy, Michael. Thank you very much for posting your installation report and the pictures. We will have to replace our bedroom air conditioner maybe next year so your post will be saved on my laptop for future use. Thanks again, Regards, Jack and Liz Pearce Fulltiming in a 1993 Wanderlodge WB40 Currently in Cowtown RV Park, Aledo Heading for Amarillo on Monday, hope to meet up with John Finn |
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