With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If not too hot to hold, then you have to look at the actual engine temp and if that is up, if it is, then your looking at a restricted heater core.
If you find that they are both too hot to hold, then the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
If they are both not too hot to hold on to, then you either have a restricted heater core or the system is not completely full and getting air pockets for some reason.
May, 21, 2011 AT 2:10 PM
Replaced stuck open thermostat-did not help. Re: heater core hoses-one is hotter than the other but not too hot to touch at full operating temp.
Cannot find heater control valve in heater hose that should be there per car books and internet? Is this missing? (Just bought this car.)
Are there self-test diagnostics on Climate Control Panel? Using manual override not EATC.
Going to remove heater hoses and try to flush core while still in car as not looking forward to removing entire dash to replace heater core. Would full radiator system flush heater core as well?
How do you clear air pockets from system?
Thank you very much for your assistance. I appreciate knowledgable help such as yours.
May, 21, 2011 AT 2:14 PM
From what you're describing, the core is plugged up. You can try removing the hoses and back flushing it with water pressure but you will probably need a new heater core.
May, 21, 2011 AT 3:16 PM
I think you are correct. I will try flushing just the core but would a full cooling system flush be advised as well in addition to this or maybe instead of this?
What about the missing heater control valve?
May, 21, 2011 AT 3:20 PM
It might be a good idea to clean the rest of the system if it shows any sign of contamination but your problem right now is with the heater core so that needs special attention.
May, 21, 2011 AT 4:21 PM
I appreciate your replies. I am flushing the heater core right now.
Do you know anything about the missing "heater control valve"? It is supposed to be inline in one of the the heater core hoses but it is not there.
May, 21, 2011 AT 6:54 PM
Apparently you didn't read my first post. This car uses an air blend door, not a water valve. Coolant circulates 100% of the time
May, 21, 2011 AT 8:26 PM
I did read your post but misunderstood. Sorry. I thought it had both components. I have researched this so much I have confused myself beyond the point of return as both parts are listed everywhere for this model and in the repair manuals as well. I flushed the heater core and now both hoses get hot evenly but still no heat. I am now researching replacing the air blend door which looks worse than replacing the heater core.
I think I'll take a break as it is near 70 degrees and will be near 80 degrees tomorrow. But I'll need heat next week.
I really appreciate your assistance with this. Thank you for your time.
May, 21, 2011 AT 8:29 PM
The door itself is about 8 hours to change but the actuator is the more common failure. You will have to remove the actuator to see if the door is stuck or damaged.
May, 21, 2011 AT 8:31 PM
Got it. Thanks. Looks like I might as well replace the heater core while all this is undone anyway.