RV Automatic Transfer Switch Dead - AC Power Troubleshooting & Repair

Bottom Line Up Front

Your ATS with display is experiencing a classic internal relay failure after 21 years of service. The fact that you have shore power coming into the "IN" terminals but nothing going "OUT" to your coach panel, combined with the generator not triggering the transfer, points to failed internal contactors or control circuitry. Even though you manually pushed the contacts and they stayed engaged, the electrical connection isn't being made - this typically indicates burned or pitted contact surfaces, or the solenoid coil that holds them closed has failed. This is a common failure mode for ATSs in this age range, and unfortunately it's not a simple DIY fix due to the high-voltage components involved.

Root Causes

After 21 trouble-free years, your ATS is experiencing age-related failures in its switching mechanism. Common causes include burned or corroded main contactors that no longer make proper electrical connection even when mechanically engaged. Over time, the high current loads from your coach (especially AC units) create arcing that damages the contact surfaces.

The control circuit may also have failed - this includes the solenoid coils that actuate the contactors, the voltage sensing circuits that detect when to switch sources, or the logic board in the display unit. Since your generator won't trigger the transfer either, this suggests the problem is in the main switching assembly rather than just the shore power detection circuit.

Environmental factors also play a role after two decades. Moisture, dust, and temperature cycling can cause internal corrosion and component degradation. The protective contact cover you removed may have allowed contaminants to accumulate on the contact surfaces over the years.

Before You Start

CRITICAL SAFETY WARNING: Turn OFF the main breaker feeding your ATS and disconnect the generator before any further inspection. ATSs contain live high-voltage circuits (120V or 240V depending on your RV's electrical system) that can be lethal. Even with power off, some ATSs may contain capacitors that retain dangerous charges - if your unit has large capacitors, discharge them using a proper capacitor discharge tool or have a qualified technician perform this step before touching any components.

You'll need a multimeter capable of reading 240V AC safely, basic hand tools, and good lighting. Have your ATS manual handy - if you don't have it, Automated Engineering Corp may still have documentation available for your series. Take photos of all wire connections before disturbing anything.

Check if your unit is still under any extended warranty - though unlikely after 21 years, some manufacturers offer longer coverage on transfer switches. Also verify your coach's main electrical panel breaker hasn't tripped, as this could create similar symptoms.

Consider this repair's complexity honestly. ATS internal repairs require working with high-voltage components and precise adjustments. If you're not completely comfortable with electrical work at this level, this is definitely a job for a qualified RV technician.

The Repair Process

Start by verifying the problem with your multimeter. With shore power connected and main breaker OFF, you should read your system's voltage (120V or 240V) at the shore power source and 0V at the ATS output terminals - this confirms your diagnosis. Check the neutral and ground connections as well, as a poor neutral can cause similar issues.

Remove the ATS from its mounting to access the internal components. Your ATS uses electromagnetic contactors that should show continuity between input and output terminals when energized. Test the solenoid coils for continuity - they should read within the manufacturer's specified range (verify with dealer). If open circuit, the coils have failed.

Inspect the main contact surfaces carefully. Even if they close mechanically, burned or pitted surfaces won't conduct properly. Professional contact cleaning or replacement requires special materials - standard sandpaper will make things worse. The contacts may need professional reconditioning or complete contactor replacement.

Test the control voltage circuits that operate the contactors (voltage varies by manufacturer - check your unit's specifications). The display unit contains the logic circuits - if it's showing error codes or not responding to input changes, internal board failure is likely. Check continuity of control wiring between the display unit and contactor coils. Test voltage output from the control board when transfer should occur. Verify proper grounding of control circuits. If control voltage is present but contactors don't engage, the problem is likely mechanical contactor failure.

Professional Help Needed

Given the age of your ATS and the symptoms you're describing, professional diagnosis is strongly recommended. A qualified RV technician can properly test the contactors, control circuits, and determine if repair or replacement makes economic sense. They'll have the proper test equipment and safety procedures for working with transfer switches.

Expect diagnosis costs of $150-250, with repair costs potentially ranging from $400-800 depending on which components have failed. A complete ATS replacement would run $1200-2000 including labor. Many shops can rebuild your existing unit if parts are available, which may be more cost-effective than replacement.

If you decide to replace the entire unit, consider upgrading to a newer model with better surge protection and digital controls. Your existing wiring should be compatible, but code requirements may have changed in 21 years. A professional can ensure proper installation and compliance with current RV electrical standards.