siddons13 Posted October 14, 2023 I'm having an issue with my 2016 NV 3500 not blowing hot air. The control valve under hood has been bypass and its warm going into firewall. The heater core is warm under dash and all the actuators seem to be working fine. Is there something I'm missing? Quote Share this post Link to post Share on other sites
crusty Posted October 17, 2023 Just at idle, but works at speed? That is you are low on coolant. All modern Nissan trucks are like this. Also note that the radiator is the INCORRECT place to top off the coolant. The pressurized coolant bottle is what needs to be topped off. If it is low, the suction line on the bottom will suck air into the system. The heater core gets a bubble in it. The good news is it is as simple as fill it and drive. The internet is full of complex solutions to filling the cooling system. The cooling system is designed to rid itself of bubbles just by driving around. You need to get some RPM in the engine driving around so the water pump will actually push water through the bubble. Once you get the bubble moving around it will vent itself in the coolant bottle. 1 radin2son reacted to this Quote Share this post Link to post Share on other sites
