Keep Cool and Diagnose a Bad Volvo S70 Heater Core
With the press of a button, you can get hot air blowing from the air conditioning vents inside your Volvo. This is made possible by a heater core that uses your hot engine coolant to warm your cabin in a way that's similar to how your radiator cools it down. As the hot coolant travels through its tubes, its fins begin to dissipate the heat into the outside air while a fan blows the heat out to the cabin. This may seem simple, but you will surely appreciate this on a cold night or during a winter's drive. You will need to ensure that your Volvo S70 heater core isn't showing any signs of wear and tear so that you can confidently drive outside when the temperature's freezing. Otherwise, the frightful weather will eventually get inside your vehicle and cause goose pimples, shivering, hypothermia, or even death.
Cracks and leaks
Cracks in the core or in its heater hose will cause the engine coolant to leak out. Apart from inefficiently heating up your S70, a leak can also cause trouble for other parts of your car. Because the heater core is located under the passenger's side of the dashboard, the coolant can soak your carpets. If you notice a wet spot in this location that produces a sweet smell, a fogged-up windshield, a greasy film on the windows, and a low amount of coolant in the reservoir, then you definitely have a leak on your hands. You'll need to replace the heater core and/or your hose, refill the coolant, and clean and dry your carpet when this happens.
Slow warm up, noises, and erratic functions
A malfunctioning Volvo S70 heater core has many signs that may be unnoticeable until you press that heater button. These include taking more than ten minutes for your cabin to warm up; a grinding, swooshing, or clanking sound that you can hear whenever your heater is turned on; "heated" air that isn't hot enough; and the continuous fluctuations of the vent's temperature. If you notice these signs, then you'll need to replace your heater core at once.