# a not so typical heatercore issue (03)



## catmoosebear (Nov 20, 2014)

I purchased a rebuilt 03 altima last august and have not had strong heat in the car ever. considering I live where weather gets lower then -30c i decided this year to look into it. 
First off it was throwing a code which was a thermostat failure. OK. 
Coolant temp gauge in the car was reading significantly lower then what the engine was performing (radiator fan on and the gauge not reading anything on the dial, after 15 minutes driving the needle finally points at the first bar)
I tried bleeding it,
It was also not leaking coolant and (here`s the fun part) the input to the heater core was hot and the output was cold. (hang on!)
So naturally after much searching and googling I bought a new thermostat, drained the entire system and checked the thermostat that ran from the radiator to the engine (boiling water opened right up) and replaced the outflow thermostat with a brand new one. While it was open I checked to make sure that there was no blockage in the heater core by running tap water from a hose through both the input and output of the heater core ( brown tinted water came out) but the overall flow was consistent with what was going in. I put everything back together bleed the air and sure enough, nothing changed. heater input is hot, output is cold. No leaks still have a check engine light and no heat.

Its also worth noting that I broke the thermostat housing when replacing the thermostat and as such replaced the housing and sensor at the same time with a junkyard part

sadly the worst things about this is that i have more time then money

If anyone has any idea of what might be the issue please let me know. at this point I've done everything but disconnect the heater core itself (its thats the case the car is doomed to be cold)

Thanks!


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## smj999smj (Jan 1, 2006)

These cars were notorious for trapping air in the heater core. There was a Nissan service bulletin that had instructions on to how to properly bleed the cooling system. It was #NTB02-047c and you can download a copy of it here:

2003 Nissan Altima Service Bulletins - Nissanhelp.com

Another possibility could be that the mode door actuator that controls the airflow through or around the heater core could be not working.


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