Experiencing problems with the rear AC in your 2017 Mercedes Sprinter van? You’re not alone. A common issue, especially during hot weather, is a malfunctioning rear air conditioning system. This guide, drawing from real-world experiences, will help you troubleshoot potential problems and get your Sprinter’s AC blowing cold air again.
One often-overlooked area to check is the electrical connections located under the driver’s seat. As one Sprinter owner, Dennis, pointed out, a critical fuse and associated wiring connectors reside in this location. Specifically, look for a fuse connected to thick brown wires. These wires often run from the back corner of the seat box, down under the driver’s side stepper (the ABS plastic cover), and connect to two flat break/socket connectors. This area is unfortunately prone to moisture accumulation from road splash.
Corrosion at these unprotected connectors can lead to significant electrical resistance, effectively cutting power to your rear AC. In severe cases, the connectors may even separate completely due to corrosion. Dennis’s recommended fix involves replacing these vulnerable connectors with standard household or commercial wiring jointers. Soldering and tinning the connections, followed by sealing them with shrink wrap, provides a more robust and moisture-resistant solution. Don’t forget to replace the fuse and clean the fuse box contacts as well.
Another potential culprit in rear AC failures, as shared by Sprinter owner Grahm, is the relay. Grahm experienced a sudden rear AC shut down during a road trip. While the condenser unit seemed to be operating, there was no blower function inside the van. Troubleshooting his 2017 Mercedes Sprinter, Grahm located the AC relay (K9) in the footwell and under the driver’s seat. Replacing this relay restored the rear AC function. Interestingly, even after putting the old relay back in, the AC continued to work, suggesting a possible intermittent issue or a temporary reset by removing and reinstalling the relay.
While relay replacement can sometimes resolve the issue, it’s crucial to investigate the underlying cause, especially if the problem recurs. In the case of the 2017 Mercedes Sprinter rear AC, both fuse/connector corrosion and relay malfunction are plausible causes. Therefore, a thorough inspection of both the under-seat wiring and the AC relay is recommended when diagnosing rear AC problems in your Sprinter van. Addressing these potential weak points can help ensure reliable cooling for your passengers, especially during demanding conditions.
