Heater blows cold air. Low on coolant 3 months ago.filled it fixed heat issue. Oil change at that time. No coolant in oil. Does not blow white smoke or drip out of exhaust. Low on coolant again at this time, now overheats a little bit but not all the time. No visible leaks. Cooling system was pressure tested last time it was low by dealership. No pressure leak. Another Nissan mechanic said it has open system and is normal.
This could be caused by a variety of things such as low coolant levels, a clogged heater core, a faulty thermostat, a faulty blower motor or heater core bypass hoses that are leaking. I would also recommend checking the water pump to be sure it is operating as it should. I would suggest having an expert from YourMechanic come to your home to diagnose and repair.
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