Need help troubleshooting charger

I have a Manzanita Micro PFC20 in my EV Chevy truck (I bought truck already converted). When I plug in, no matter how much charge is on batteries, charger goes directly to timer/shutdown mode–yellow limit light is on and blue timer light is blinking. So, it doesn’t fully charge. (I can get a full charge by manually turning charger back on–need to do this 3 or 4 times over the night). Is this a charger problem or wiring? What should I be looking for? Any help is greatly appreciated