03 Explorer heat not working well

[03AZExploder]

Lately my heater isn't blowing as hot as it usually does. I've also noticed that my temp gauge won't even get to halfway after 30+ min of highway driving. The gauge doesn't move or fluctuate at all, gets to the first line and stays there. Coolant level seems fine, could this be a thermostat? Or some other sensor?

 

[Mr Dubya]

Start with the thermostat swap.


-Dubya

 

[03AZExploder]

Start with the thermostat swap.


-Dubya

I'll do that tonight. I've also read about some water temp sensor that's also on the t-stat housing. Would it be wise to replace that as well while i'm there?

 

[Mr Dubya]

Not too familiar with that. I have high hopes it may just be the thermostat - always seems to be.

 

[ponkotsu]

Now with the cold I'm having same issue on my Aviator. Heat not so overwhelming. Temp gage never gets to half way mark. Anyone know what is normal position for the temp gage? I think my scan data is telling me I'm hitting 80C which seems low but not terrible.

 

[Mr Dubya]

The normal position for me during winter is at about the half-way mark, maybe a sixteenth of an inch above? When I had low-temp problems last year (thermostat replacement fixed it) it wouldn't get to the half-way mark, usually peaking an eighth of an inch below it.


-Dubya

 

[03AZExploder]

Now with the cold I'm having same issue on my Aviator. Heat not so overwhelming. Temp gage never gets to half way mark. Anyone know what is normal position for the temp gage? I think my scan data is telling me I'm hitting 80C which seems low but not terrible.

That sounds exactly like what im experiencing. This time last year my heat would melt my face, not so much right now. I drove for an hour last night and it never moved past the first tick mark. Its always sat in the middle of the gauge for me. Hopefully it is just the thermostat.

 

[ponkotsu]

That sounds exactly like what im experiencing. This time last year my heat would melt my face, not so much right now. I drove for an hour last night and it never moved past the first tick mark. Its always sat in the middle of the gauge for me. Hopefully it is just the thermostat.

I'll probably change the t-stat and flush the core this weekend. It's basically routine maintenance anyway so not really wasted effort. If that doesn't fix it, then not really sure what else it could be.

 

[ponkotsu]

So got around to this today. I didn't bother changing the t-stat as it is running at a constant 90C, which is normal. Flushed out both heater cores with plain water first. Seems like they were already super clean and water flowed freely both directions. Then I ran CLR in them for about 10 minutes. Again, absolutely nothing came out and water flowed freely. But, I do have much improved heat. I think there was air in the system. I was really careful when filling the heater cores to get all the air out.

If you do have the auxiliary core in the rear, you have to pinch off the hoses one at a time to direct your flow. Not too difficult.