Howdy All
My '05 Nav. has lost it's hot defrost so I've been looking for symptoms, etc.
I ran the on board DATC self test and got a 2266 code. From other information that looks like a Lower Blend Door Failure but there still just didn't seem to be any hot air making it's way anywhere into the passenger cabin so I checked the hot water valve. With the engine at operating temp and manually holding the water valve open the cabin gets lots of hot air. The valve itself looks like it will hold a vacuum but the line connecting to it doesn't measure any vacuum at all.

I'm wondering if anyone can tell me if this model has the Dash Vacuum Manifold? And if these symptoms would sound like this manifold would be the problem?

Thanks in advance for any help.

 

The vacuum shut off should only pull a vacuum when the AC is on. When you're trying to get hot air, there should not be any vacuum on that valve. No vacuum = open valve. Do you get hot air anywhere at all?

 

No, there doesn't seem to be hot air anywhere at any time. From your description it sounds like I didn't understand the Water Valve. If I understand what you are saying the vacuum to the water valve would only be present when the AC is on, correct?

 

Yes, AC on should pull vacuum on that valve and close it, shutting off the hot coolant flow to the heater core. If this valve is open, no vacuum, it allows hot coolant to flow through the heater core

 

So with hot water running through the heater core, and no hot air in the passenger cabin or on the wind shield is it possible to diagnose if I am headed into a blend door repair or vacuum solenoid?

I really don't want to go after the blend door and find out that it was the vacuum solenoid.

 

If the heater core is receiving hot water, and you can feel that the inlet and outlet tubes are getting hot, then you have a blend door issue. It could be the actuator (usually this gives off a clicking sound in the dash, like stripped gears trying to move) or a failure of the blend door itself, either broken or jammed. Since you have a fault code on a blend door, that may be your issue. You will have to diagnose it further though