Caravan World — 6 August 2012

VERY FEW PEOPLE would choose to travel without an air-conditioner, but not all vans have them. While it’s true fitting one to your van is probably a job best left to professionals, here’s a look at what would be required if the more confident and capable DIYers out there wanted to have a go. We recently saw some pros fit a roof-mounted Dometic E2200 unit into a 4.58m (15ft) pop-top with an aluminium roof.

With pop-tops like this one, the unit is best fitted towards the back because it makes lifting the roof section easier than a centrally-mounted unit would. And in the case of this van, the power is sourced from under the rear bed – an added benefit of a rear-mounted unit.

Some vans also have a factory-installed support bracket under the cladding, which makes cutting the hole and fitting the unit very easy.

An air-conditioner like this Dometic has most of the fittings required with the unit, but you will also need silastic sealant, a support bracket (if you don’t trust your welding skills, companies like Sydney’s Barnes Caravans can sell you a pre-fabricated unit), some timber for the roof cavity support, wiring to the appropriate amperage (10A here), a plug and connectors and, in this case, 12V wiring to re-route the roof downlights. Some self-tapping screws will also be required.

Tools you’ll need include a mallet, quality box cutter, screwdriver and various bits, square edge rule, tape measure, pencil or marker, heat gun (a hair dryer will do) conduit and tin snips.

When it comes to the 240V wiring involved, bring in a licensed electrician.

The first step is to find exactly where you’ll position the unit. As mentioned above, this one was going onto an ‘unknown’ roof – we weren’t sure where the existing wiring was – and one where we were pretty sure no air-conditioner supports were in place.

You are sometimes able to use an existing hatch as your entry point and, in other cases, the air-con position is already pre-existing from the factory – all you need to do is hacksaw a hole in the right place, a 10-minute job. But make sure of the exact position before you go drilling or cutting anything.

Once we worked out where the unit would go, we marked out the support-bracket position and trimmed the ends off the bracket to suit the roof. We then marked out the square where the aperture would be cut and drilled through at the corners, helping to mark out the area to cut out the ceiling panel inside the van.

We then got stuck in with the mallet and box cutters. This process is slower than using a jigsaw, but it’s less messy and cuts less deeply, which is vital to avoid cutting through any wires already in the roof cavity.

With the square ceiling panel cut out (and the corresponding roof panel also cut, with either tin snips or the mallet and box cutters), it was time to check for wiring.

In this case, ceiling lighting wiring ran in a conduit through the centre of our cut-out, so once we removed the insulating foam we could cut the conduit out and snip the wires to re-route them around the cut-out. Because we were careful not to cut the wires around the edges of the cut-out, we had plenty of room to snip and extend the wires.

We used a heat gun to melt away the foam insulation, allowing us to fit a support frame around the the aperture. This avoids the risk of the relatively weak roof and ceiling crushing up against the support frame when secured to the main air-con unit. If the roof crushes it will compromise the seal between the support frame.

Before supporting the aperture, we needed to plumb wiring though to the corner of the roof, where we would later cut a hole and plumb the wire down to the 240V plug under the bed, via the side cupboard. This is done by melting a channel through the foam insulation, using a section of conduit heated up at the end and pushed through to the corner from the air-con aperture.

With four pieces of timber cut to suit, each was then tapped into position around the periphery of the aperture to give it support.

We put a bead of silicone to seal the support bracket to the roof. The bracket itself was slightly bowed so it would not add any pressure to the centre of the roof with the weight of the air-con unit on it, but rather spread the load more evenly. We then fitted the support bracket, lined it into position and drilled at the corners.

Once the bracket was in position, we mounted the main unit on top. The Dometic came with a thick rubber seal, so there was no need to silicone it against the bracket. The brackets that hold the air-con main unit to the van aperture were then secured. This sandwiched the ceiling, roof, support bracket and main air-con unit together and spread the bead of silicone applied earlier to an effective seal.

It was then a matter of attaching the interior fascia unit with its filters and vent covers, and finishing off the wiring at the wall unit powerpoint under the bed by cutting the lead to the appropriate length and fitting a plug. This is a job for an electrician. Also, for those thinking about hardwiring the unit: you can’t unless you have an electrician’s licence.


01 Two supports – the one on the left with welds ground smooth.

02 Dometic E2200 air-con and installation kit.

03 Measuring and marking up support bracket.

04 Some vans have an air-con support bracket pre-fitted at the factory.

05 Drill through the roof to mark out the square in preparation for cutting.

06 Measure the square inside the van from drill holes made from outside. 

07 Cut out the square using a strong box-cutter and hammer, ensuring wires are not cut through.

08 Peel away roof lining – do the same on the outside.

09 Use a heat gun to shrink foam so timber supports can be fitted. 

10 Roof light wiring cut, extended and rerouted around air-con duct hole.

11 Heat up conduit with heat gun to make channel through foam for wiring.

12 Air-con’s 10A wiring routed through the roof to the corner, where it was plumbed through cupboard to powerpoint under the bed.

13 Apply bead of silastic to bond and seal bracket to aperture.

14 Seal with a bead of silastic at support bracket ends and screw into place with self-tapping screws.

15 Tap timber support frame into place.

16 Air-con unit has a thick rubber seal in this case, so no sealant is needed to fit to support bracket.

17 Air-con unit in place. Note how support bracket is bowed upwards to spread weight more evenly.

18 Brackets secure main unit to roof and squeeze out silicone bead to effective seal.

19 Ask an electrician to wire air-con to power with the appropriate connector.

20 Use foam spacers (supplied with the air-con) to seal main unit outlet air duct to internal fascia.

21 With filters fitted, now it’s time to plug in the main unit to the internal fascia.

22 Bolt the fascia to main unit, then inlet filters and covers will be fitted.
(Right: w
ith wires routed though to under-bed power outlet, plug added.)

24 The finished product.

Source: Caravan World May 2012

More RV tech articles


how to tutorial tips fit air conditioner caravan knowledge step by step air-con tech

External Links