Your heating and cooling gear works hard on a big lap, and it only lets you down when you have skipped the basics. This reference sets out what to check on your air conditioner, diesel heater, gas appliances, hot water system, fans and seals, and how often to do it, so nothing catches you out in the middle of nowhere.
The Maintenance Schedule at a Glance
Most heating and cooling failures on the road are not really failures. They are neglected filters, perished seals, a fuel tank run dry, or an anode nobody ever changed. Keep on top of the list below and your systems will run for years. The table sets out the core jobs, what you are actually checking, and how often to do it.
| Item | What To Check | How Often |
|---|---|---|
| Air con filters | Pull the return-air filters, wash in warm soapy water, dry fully before refitting | Every 2 to 4 weeks in use |
| Air con roof seal | Gasket between the unit and roof for cracks, flattening or water marks on the ceiling | Every 6 months, and after rough roads |
| Air con drain | Condensate drain holes and channels clear of dust, leaves and insects | Every few months in use |
| Diesel heater run | Fire it on high for 15 to 20 minutes to burn off carbon, even in summer | Monthly, year round |
| Diesel heater exhaust and intake | Exhaust and air intake clear, secure, unblocked and vented well clear of the van | Every 3 months, and start of the cold season |
| Diesel heater fuel | Tank topped up and clean, fuel not old or waxed, pick-up screen clear | Before each cold trip; annual glow plug or screen service |
| Gas appliances | Full gas system and appliance check by a licensed gasfitter; leak test | Every 12 months (or per your state) |
| Carbon monoxide and gas alarms | Press to test, check the use-by date, replace flat batteries | Monthly test; replace unit per its expiry |
| Hot water anode | Sacrificial anode (storage systems) for wastage; replace when heavily eaten | Inspect every 6 months; replace yearly or as needed |
| Hot water flush and valves | Drain and flush the tank, exercise the pressure relief valve, check for leaks | Every 6 to 12 months |
| Fans and vent covers | Roof-fan blades and screens cleaned, blades spin freely, no rattles | Every 3 months in use |
| Seals and insulation | Window, door, hatch and vent seals for gaps and perishing; insulation dry | Every 6 months |
Air Conditioner
The single most valuable thing you can do for a caravan air conditioner is keep the filters clean. Blocked return-air filters choke airflow, which makes the unit work harder, cool worse, ice up and eventually burn out the fan or compressor. Pull the filters every two to four weeks in the tropics or over a hot summer, wash them in warm soapy water, let them dry completely, then refit. It takes two minutes and it is the difference between a unit that lasts a decade and one that dies in three summers.
Twice a year, get up on the roof and look at the mounting gasket, the foam seal squashed between the unit and the roof opening. Corrugations and UV slowly flatten and crack it, and a failed roof seal is the classic cause of water dripping through the ceiling in the first big downpour. While you are up there, clear the condensate drain holes and channels of dust, leaves and mud-wasp nests so water runs off outside rather than pooling on the roof or finding its way in.
A soft brush and a can of compressed air clears dust from the roof-unit fins without bending them. Bent or clogged fins cut cooling performance and are a common reason a unit that used to cope suddenly cannot.
Diesel Heater
Diesel heaters reward one simple habit: run them. Fire the heater up on its highest setting for fifteen to twenty minutes once a month, all year round, even through summer when you do not need the heat. A good hot burn clears carbon out of the combustion chamber and glow plug, which is the single biggest thing you can do to keep the unit reliable. Heaters that only get used in a cold snap and then sit idle are the ones that soot up and refuse to start when you finally need them.
Every three months, and again at the start of the cold season, check the exhaust and combustion-air intake. Both need to be clear, secure and unblocked, with the exhaust venting cleanly outside and well away from windows, vents and the underfloor. A blocked or badly positioned exhaust is the number one cause of diesel heater trouble and a genuine safety risk. Keep an eye on the fuel too. Top the tank up before a cold trip, avoid running very old or waxy diesel, and have the glow plug and fuel pick-up screen serviced roughly once a year if you run the heater hard.
Gas Appliances
Gas is where maintenance stops being a DIY job. Your gas cooktop, gas hot water and any gas space heater share a system of regulators, hoses and connections that need a licensed gasfitter to inspect and leak-test. Book a full gas check every twelve months, or more often if your state or your insurer requires it, and always after any work on the gas system. In between professional checks, keep it simple: look over the rubber hoses for cracking and perishing, keep burners clean, and never poke around inside a regulator or appliance yourself.
The one gas-related job that is squarely yours is the carbon monoxide alarm, and every van that runs gas or a fuel-burning heater should have one. Press the test button monthly, replace flat batteries straight away, and note that CO alarms have a service life, usually five to seven years, so check the printed expiry and replace the whole unit when it is due.
Gas work and the sealed refrigerant circuit inside your air conditioner are jobs for licensed professionals, not weekend DIY. In Australia it is illegal to carry out caravan gas fitting without a licence, and opening a sealed refrigerant system without the right ticket is both against the law and dangerous. Leave both to the pros.
Hot Water System
If you run a storage hot water system, the part that quietly determines its lifespan is the sacrificial anode. It is a threaded rod designed to corrode so your tank does not, and it wears away over time, faster on bore or mineral-heavy water. Inspect it every six months and replace it once it is heavily eaten, usually about once a year. A ten-dollar anode changed on time saves a several-hundred-dollar tank.
Every six to twelve months, drain and flush the tank to clear sediment, then exercise the temperature and pressure relief valve by lifting its lever and letting it snap back, which stops it seizing shut. Check the fittings for weeps and leaks while the water is running. Tankless and continuous-flow systems have no anode, but still deserve a periodic descale if you have been drawing hard water, plus the same look over hoses and connections.
Flush the hot water tank at the end of a long stint on bore water rather than waiting for a set date. Mineral-heavy water lays down sediment far faster than town supply, and a quick flush now prevents a smelly, sluggish system later.
Fans, Vents, Seals and Insulation
Roof fans and vent covers do a lot of the cooling work when you are off grid, and they clog with road dust, pollen and insects. Every three months in use, clean the blades and insect screens, check the blades spin freely, and chase down any rattles before they wear a bearing out. A clean, balanced fan moves far more air and draws less power than a dusty one fighting itself.
Seals are the unglamorous job that decides whether your heating and cooling is even worth running. Twice a year, work around every window, door, hatch and vent seal looking for gaps, hardening and perishing rubber. A perished seal lets your cool air leak out in summer and your heat bleed away in winter, and worse, lets water and dust in on corrugated roads. While you are at it, check that insulation behind panels and around the fridge vents is dry and in place, because wet or displaced insulation is both a heat leak and a mould risk.
- Clean the air con filters every few weeks. It is the highest-value job on this list.
- Give the diesel heater a hot run every month, all year, and keep the exhaust clear.
- Book a licensed gas check yearly and test your CO alarm monthly.
- Change the hot water anode before it disappears, and flush the tank yearly.
- Keep fans clean and seals sound, or the rest of your work leaks straight out.
What This Means in Practice
You do not need to memorise the whole table. The trick is to fold these jobs into rhythms you already have. Make the filter wash and the CO alarm test part of your monthly reset, the same weekend you rotate the pantry or check tyre pressures. Put the six-monthly jobs, roof seal, anode, window seals, on the calendar twice a year, and tie the diesel heater’s hot run to the first cold snap and then once a month after that.
The bigger jobs, the licensed gas check and anything touching the air con refrigerant circuit, get booked with a professional when you are passing through a town with a caravan service centre. Plan those around your route rather than leaving them until something breaks in a place with no workshop for 400km. Do the small things often and the big things on schedule, and your heating and cooling gear will simply keep working, which on a big lap is exactly what you want from it.
Last updated: July 2026.
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