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Old 12-07-2010, 10:29 AM
John Belculfine John Belculfine is offline
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2003 Altima
 
Join Date: Mar 2010
Posts: 9
Default 2003 Altima - Heater Problem

I have a 2003 Altima, 3.5 V6 with 192,000. During the past couple of winters, the heating system has been blowing cold air into the cabin at idle during normal operating temperature. The system blows warm air during high-idle warm-up and if I rev the engine in neutral and while driving. At red light, cold air begins to enter the cabin. Heating/cooling system is the automatic climate control, set-it and forget-in type.

In an effort to resolve the issue, I removed the heater core hoses from the top right of the engine and forced water to clear any blockage from the heater core. Some gunk came out, but nothing that would suggest partial blockage. At the same time, I replaced the antifreeze by draining the radiator, cleaning out the overflow, and also replaced the upper and lower radiator hoses for the first time.

The thermostat was not replaced as I do not believe I would get any heat if it was defective. The radiator cap was not replaced either, it appeared to be OK. No leakage of antifreeze, no noise from the water pump. Lastly, I have selected the option of not recirculating the air from outside to see if there is any change - no such luck.

The car is in very good operating condition and other than basic maintenance, has not had any major repairs during its history. I am one of the lucky ones.

Any ideas? Thank you!

John
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