Heater Core won't get hot/stay hot.

[martinqc]

I have been having issues with my heater for a bit and now it won't get hot or stay hot. Allow me to explain...

1. If I start the car and allow it to idle, the coolant temp rises, but the heater never gets hot. It does get luke-cold like it's trying, but no further.

2. If I start the car and switch to the heater while leaving the fan off, the heater core gets hot. Once I turn the fan on, the air cools off back to luke-cold.

3. The defroster does not defrost. Air blows, but no improvement.

4. recently replaced my cabin filters, all tests done with air in recirculation mode.

5. When it did work, it took some time to get warm.

6. Attempted to 'bleed' air out of the system, but not sure if that accomplished anything. Don't know if there is air in the system or a blockage.

I would like to say that I am somewhat skilled with working on cars. I'm good at following directions. I have a Haynes manual, but this is something I may need 'by-the-numbers'. Please have mercy on a poor xTerra lover's soul. This car saved my family's and my lives. I want to get it back in working order.

[Chef]

Chang out your thermostat and get new coolant and mix 50/50 with DISTILLED water

[Xterra Mike]

You may have a blockage in your heater core. Take your hoses off the firewall (be carefull they might be brittle) and spray some water in one hole then spray in the other hole. See if anything comes out.

[Gsimpson2G]

Originally Posted by Xterra Mike

You may have a blockage in your heater core. Take your hoses off the firewall (be carefull they might be brittle) and spray some water in one hole then spray in the other hole. See if anything comes out.

+1, really sounds like this.

[martinqc]

Appreciate the fast replies folks. I do know where the hoses enter the firewall, which is good. Do I need to shield the water coming out from the engine or anything?. btw, I do think I have a thermostat issue also, just not the source of this issue. I will give these a try and let you all know how it turns out.

[RacerXXL]

What year X? If it's a 2nd Gen you may want to check these out.

http://www.thenewx.org/forum/showthread.php?t=35941

http://www.thenewx.org/forum/showthread.php?t=24370

[Domasticus]

I recently had the same problem if flushing your core does not work then depending on how old your xterra is it may have rusted on the inside like mine had (which we replaced) it will keep it from getting hot also if you do change it yourself and your airbag light comes on after you put everything back together then you need to reset your air bag sensor to passengers seat by turning you key to on and waiting for airbag light to go off as soon as it does then turn your key to off and count to 5 Mississippi do this 3 time and you air had light will blink slower let it do this for another 5 sec then turn your key back to off and when you start it it should no longer be on
Airbag tip is for saving you the trouble I had

[martinqc]

The core does get hot, if the fan isn't running. I hope it is not a core replacement. I saw in the book where it's located and what has to be removed to get at it. How much did your replacement core run you?

btw, the air bag thing already happened to me when I pulled out my front seats for some detailing and when I reconnected the seats it popped up on me. I appreciate the heads up though.

[Domasticus]

Mine was about $2-300 for core and we did the work on it ourselves

[Chef]

Try the thermo first before you take out the core. It's probably stuck. Keep it simple