Webasto Cool Top Trail 28V Quick Guide
Simple Rhinomax-specific instructions to operate and troubleshoot your Webasto Cool Top Trail 28V variable-speed roof air conditioner. For full technical information, download the complete user manual below.
⚙️ Basic Operation (Rhinomax Edition)
Follow these steps for everyday use of your Cool Top Trail 28V in a Rhinomax camper.
Power & Start-Up
Make sure your camper is connected to a suitable 230 V supply or quality inverter / generator and that circuit breakers are ON. Use the ON / OFF button on the remote to start the unit. The compressor may take up to 3 minutes to begin cooling or heating – this is normal protection for the system.
Selecting Mode & Temperature
Press MODE to cycle through COOL, HEAT, DRY, FAN and AUTO. Use ▲ / ▼ to set the temperature between 16–30 °C (not available in FAN-only mode). In AUTO, the unit chooses heat or cool automatically to hold your setpoint.
Fan Speed, Turbo & Direction
Press FAN to choose Low / Med / High or AUTO (auto fan in COOL or HEAT). Use TURBO for maximum output when the cabin is very hot or cold. Adjust the air louvres on the ceiling unit to direct airflow where you need it.
ECO & Sleep Modes
Press ECO to toggle ECO1 (≈70% capacity) or ECO2 (≈40% capacity) for quieter, more efficient running – ideal for night use or when power is limited. Use SLEEP in COOL or HEAT to gently adjust the set temperature overnight, reducing noise and energy while maintaining comfort.
🌡️ Getting the Best Performance
Simple tips to help the variable-speed system cool and heat your Rhinomax more efficiently.
Pre-Cool / Pre-Heat
On very hot or cold days, start the air conditioner early while you’re still driving or setting up (with mains / generator connected). Close doors, windows, hatches and blinds to reduce heat load.
Managing Condensation
Keep doors and windows closed while running the unit. Use a higher fan speed to reduce “sweating” on cold surfaces and allow condensate to drain off the roof as designed.
Using Generators & Inverters
The Cool Top Trail 28V requires a clean, stable 230 V supply. Check generator / inverter sizing and quality with your supplier and always fully unwind extension leads to avoid voltage drop and overheating.
Remote & Panel Control
Aim the remote at the ceiling unit display; the unit will beep when it receives a command. If you misplace the remote, you can still cycle basic modes using the touch button on the air distributor panel.
🔧 Troubleshooting & Fault Codes
If something doesn’t feel right, run through these checks before calling support.
Unit won’t turn on or no display
- Confirm the van is plugged into mains or generator and the RCD / breakers are ON.
- Check the remote control batteries and replace if the display is faint or blank.
- Verify the extension lead is fully unwound and correctly rated (min. 3 x 2.5 mm²).
- Check that the campsite or inverter supply hasn’t tripped or overloaded.
Poor cooling or heating performance
- Make sure doors, windows and roof hatches are closed and blinds / awning are in use.
- Set fan speed to HIGH or TURBO to reach temperature faster.
- Clean the return air filter – a blocked filter is the most common cause of low performance.
- Check the roof around the outdoor unit is clear of leaves, dust and obstructions.
Water dripping inside or excessive condensation
- Condensate draining onto the roof outside is normal in humid conditions.
- If water appears at the ceiling unit, ensure the van is parked reasonably level (under 5°).
- Inspect that the roof drain outlets are not blocked by dirt, sealant or debris.
- Increase fan speed and reduce moist air entry (close doors / windows).
Common error indications
- dF – not a fault: the unit is defrosting the outdoor coil during low-temperature heating.
- E0–E3 / A1 – sensor or communication faults. Switch the unit OFF, wait 5 minutes and restart. If the code repeats, contact service.
- E4 / E5 / C4 / b5–bA – protection against over-temperature, over-current or abnormal refrigerant conditions. Disconnect power and arrange inspection by a qualified technician.
If faults persist after a reset, note any error code shown and contact Rhinomax or a Webasto service agent.
🛠️ Preventative Maintenance Tips
A few simple habits will dramatically increase reliability and lifespan of your Cool Top Trail 28V system.
Clean the Air Filter
Check the return air filter every couple of weeks when in regular use. Remove, wash in warm soapy water, dry completely and refit. Never operate the air conditioner without the filter installed.
Look After the Remote
Replace the two AAA batteries when the display fades. Remove batteries if the van is stored for long periods to avoid leakage, then reset the clock and any timers.
Regular Use & Annual Check
Run the air conditioner for 20–30 minutes every 6 months to keep components lubricated. Have the roof unit, mounting bolts and heat exchangers inspected and cleaned by a qualified technician at least once a year.