Disappointing Interior Heat Saga

[RandomUserName6]

We inherited an SEL with the dual automatic HVAC a little over a year ago.

 

The typical lousy heat, much worse on the driver's side.

 

From what I've been told, the last owner would typically start the car and let it run about ten minutes before driving it in the winter.

 

And (thankfully), the ridiculous engine-out water pump and why not the timing chain repair was done about two years ago.

 

Since we've had the car, I've only managed to improve the interior heat to merely disappointing.

 

It does have front seat heaters (SEL package?) and they do work but she doesn't want to use them.  Naturally.

 

Chronologically:

 

Replaced the cabin filter.  Needed replacing but not plugged or overly dirty.

Drained coolant, disconnected the heater core hoses at the thermostat housing.

Blew thru one end, with the other end draining thru a cone paint filter.  A small amount of debris.

I assume if I can easily blow thru the open core with 60+ year old lungs, it's not even partially plugged.

Three cycles of distilled water via vacuum fill, run, drain thru a cone paint filter.

Added a quart of Motorcraft VC-1 coolant flush with distilled water via vacuum refilling.

Ran it for about an hour, drained again thru a cone paint filter.  Even less debris recovered.

Total amount of loose, coolant-colored calcium looking stuff: maybe the size of a gumball.

Installed a new Motorcraft thermostat with the jiggle valve at 12:00.

Vacuum-refilled with new Motorcraft coolant.

Took for a test drive, seemed slightly better.

Before and after this much, the car has always warmed up correctly via the dash panel gauge and doesn't overheat either.

No coolant leaks.  Reservoir stays at filled max level.  No steam in the exhaust after warming up.

Still not really acceptable to the Better Half.

Removed left and right blend door actuators and replaced both with new Motorcraft.

Cracked open the replaced drivers' side actuator: no broken teeth, no real wear or damage on the wiper/contacts.

The driver side linkage moved by hand easily with the actuator removed.

Both new actuators move when changing the temperature settings.

Though I would love to see video or pictures of the blend door linkages at each end of their correct full travel.

Pulled the kick panel HVAC fuse, ran the car for a bit, reinstalled the fuse. and no real change.

Also never any glitches or drop-outs or lack of response from the HVAC controls.

Did the system control reset thing several times but I think it only returned an 88 once.

Clear, official instructions for resetting this generation of the automatic dual zone system with Sync seem hard to come by.

The temps delivered by the car are about the same in both Dual on and off modes, at least from the drivers' experiences.

The car has never directed air flow to the wrong locations when changing the controls.  The drivers' mode actuator does move.

Looks near impossible to change anyway.

Cycling the recirculation button results in the air door opening and closing.

Also checked the key on engine off supply voltage to the in-car temp sensor: ~4.8V.

Checked resistance across the disconnected sensor: fell within the range for the given ambient temp listed in the FSM chart.

Good, as that part which was near impossible to find online is listed as no longer available.

Temp aspirator tube is fully connected with no splits.  Also cleaned off the temp sensor before re-installation.

The displayed outdoor temperature on the control panel does seem to match the actual exterior temps.

Typical March: hot and cold weather.  AC also seems merely barely okay but hadn't tested during triple digits yet.

Would like to have it recovered, the fill valve(s) replaced, and recharged to specs but nothing to do with poor heat I assume.

Still not really accepted by the Better Half; can't blame her.

 

Not a big fan of this car. At all.

 

What have I missed?

[edjunior]

Well my question would be, why do you still have it?  It seems like it's been nothing but trouble and a money pit.  Is there any reason you are keeping it?

[RandomUserName6]

On 3/28/2026 at 8:56 PM, edjunior said:

Well my question would be, why do you still have it?  It seems like it's been nothing but trouble and a money pit.  Is there any reason you are keeping it?

It was her sisters, who died unexpectedly.  So mostly a sentiment hesitancy.

[1004ron]

Sorry to hear about the family loss that led to your ownership of the Edge.

 

I don't have any specific fault finding to suggest but have not seen the lack of cabin heating reported here, which leads me to believe that there's a solution to your problem, just need to identify what that is.

[RandomUserName6]

2 hours ago, 1004ron said:

Sorry to hear about the family loss that led to your ownership of the Edge.

 

I don't have any specific fault finding to suggest but have not seen the lack of cabin heating reported here, which leads me to believe that there's a solution to your problem, just need to identify what that is.

Thank you.  I've tried another reset (after trying at least three different instructions that didn't work).  Pressing Power, Defrost (front), and Off at the same time resulted in horizontal segments at the beginning and two 88s displayed at the temperature values at the end, supposedly meaning a successful reset with no error codes.  We'll see.

[enigma-2]

With both both weak heat and weak cooling, my initial guess  would be a faulty blend door actuator. This would be especially true if the air flow is sufficient but it just isn't hot or cold enough. (If the airflow weak it suggests a different problem.)

 

First try a reset. 

1. Turn the vehicle off.

2. Press and hold the system power button and the front defrost button at the same time, for about 5 seconds.

3. Then release and press the power button again.

(This forces the system to recalibrate the climate doors.)

 

[RandomUserName6]

27 minutes ago, enigma-2 said:

With both both weak heat and weak cooling, my initial guess  would be a faulty blend door actuator. This would be especially true if the air flow is sufficient but it just isn't hot or cold enough. (If the airflow weak it suggests a different problem.)

 

First try a reset. 

1. Turn the vehicle off.

2. Press and hold the system power button and the front defrost button at the same time, for about 5 seconds.

3. Then release and press the power button again.

(This forces the system to recalibrate the climate doors.)

 

Umm...

 

I wrote in my initial post that I've already done everything you've suggested.

 

The A/C is broadly... fine.  It probably just needs a top up of refrigerant.

 

 

[enigma-2]

It would appear that you have covered all of the possibilities. Based on your statements, it really comes down to the blend doors opening all the way or a partially blocked Heather core. 

There's a easy check for the core, after the car is warmed up, feel both hoses going into the cabin. Both should be hot. In one is noticeably cooler than the other, there's a partial blockage.

 

Some time ago, Ford issued a customer satisfaction program for this generation  due to casting sand or scale corroding and plugging the heater core channels. (It's expired now, but the problems you wrote about seem to describe it to a tee. Some sand left over from engine casting worked its way to the core partially blocking the small channels. Weaker on drivers side than passenger. Never gets really hot, etc.)

 

The complaint was for a 2008 but applies to all first generation edges.

 

https://blueovalforums.com/forums/index.php?/topic/37362-poor-heater-performance/