The proper procedure to remove as much existing coolant and replace it with new is as follows:
Make sure that electric element does not get accidentally turned on with no coolant in the boiler tank. Turn off circuit breaker in your AC panel. If element gets turned on with no liquid in tank, it will immediately fail.
Drain existing coolant through drain (in your model the drain goes through the floor of the coach). You will get around 16 gallons of coolant.
Fill boiler tank with tap water. Turn on diesel burner and bring unit to operating temperature. Turn on interior heat so that you also flush out the coolant lines to interior heat exchangers.
Shut unit down and drain.
Fill unit with coolant (50% coolant and 50% distilled water).
Depending on how much diesel fuel was added, you may want to flush twice before adding proper coolant.
- Roger Berke -