Dometic air conditioning system – replace heating coil

Reading time 2 minutes

Updated – December 31, 2022

... and suddenly – only cold air!

The cause is usually a burned out heating coil. There is usually no replacement for old systems. So improvisation is required.

Before carrying out any work on live parts, all poles must always be disconnected from the power supply. Likewise, all work must only be carried out by authorized specialist personnel.
All statements without guarantee!

After removing the housing cover and the Styrofoam cover (with feeling, but with a clear upward pull all around), the old heating coil is accessible. It is held in position solely by spring force. After removing the two cable connectors from the two contacts on the heating element, it can be removed from the side panels.

According to the nameplate, the heating coil installed here is a heating element with 1,200 W. The only available replacement heating element with only 800 W was just under 100 euros.

An alternative was found Heating element with 500 W. Two of these, connected in parallel, result in at least 1,000 W. Both heating elements have their own overtemperature switch. Together with the over-temperature switch attached to the original heat exchanger, albeit somewhat carelessly, this results in a significant increase in safety.

Four 40 mm wide and 3 mm thick aluminum flat profiles, each 75 mm long, as well as two aluminum angle profiles measuring 40 x 80 x 5 mm are required for assembly.

The flat profiles serve as an assembly aid for the two heating elements. The mounting holes of the plastic brackets of each heating element are transferred precisely to the flat profile pieces.

The two holes each using a 2.5 mm drill, suitable for subsequent thread cutting with M3, are used to screw the heating element holder to the flat profile. Two additional holes at the other end ensure a hold on the angle profile. This profile, in turn provided with appropriate holes and threads, creates the connection to the existing galvanized steel sheet that previously held the old heating element.

The two red and black silicone-coated connecting wires are each connected via a 3-pin WAGO terminal to the orange cable that supplied the old heating element with voltage. Clean cable routing using cable ties ensures a secure hold and prevents unwanted contact with the heating element.

Before putting the heater into operation, check all components for mechanical stability, as well as the cable routing for intact insulation and electrically clean contact.

After assembling the Styrofoam cover and screwing the device cover together to make it moisture-proof, the test run follows: ... and warm air comes out again - operation successful!