How to Troubleshoot a GMC Suburban Heaterby Alibaster Smith
The GMC Suburban uses a heater core to heat the cabin. The heater core redirects hot engine coolant away from the engine and through the heater core to heat the Suburban. Over time, the heater core may fail. When this happens, you won't get any heat in the passenger cabin and you'll need to replace the core. However, before replacing the heater core, you should troubleshoot the heater core for your GMC Suburban.
Turn the engine on.
Turn the fan speed setting to the highest setting.
Turn the heater to the hottest setting.
Open the hood of your Suburban and grab the upper radiator hose before the vehicle has had a chance to warm up. Wait until the hose begins to heat up. Eventually, you won't be able to grab the hose anymore. This means that coolant is flowing through the hose.
Check the radiator to heater core hose. The hose running to the firewall from the radiator will run to the heater core. Check this hose to make sure that it is warm. Be careful not to touch this hose. Hold your hand over it to verify that it is warm. If it is, then coolant is making its way to the heater core.
Check the heat output in your Suburban. If you are not getting heat in your Suburban, but the coolant seems to be making its way into the heater core, then you may need a new heater core and thermostat.
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