HEATING ISSUE

[farmallbn]

We have a 2006 Nissan Pathfinder that heats great when you are driving, but every once in awhile when you slow down or come to a stop the heater blows cold air. I think it is the water pump, but could be thermostat. It is a 4.0 liter 4x4. I am mechanically inclined, so I believe I could change the water pump if that is what it is, but is there a site I could look at to get a breakdown on how to change it. It might be something else though? Any ideas. I had really good luck the last time I posted, so hopefully the same goes with this one. Thanks

[Encryptshun]

I have an '05 Xterra that was doing exactly the same thing. Flush your entire cooling system and also separately flush the heater core. Drive the vehicle and then flush the heater core a second time. If you just flush the core but not the cooling system, the gunk that clogged it the first time will just clog it again.