I have the above truck Eddie Bauer edition, I have been trouble shooting a heating problem for a while now.

What I have is luke warm heat in front and luke warm changeing to cold out of the rear heater. The truck is up to temp (gauge reading half way, I prefer the old cars where the gauges actullaly told you something), the water hoses to the front and rear are hot. and the coolant levels are up. I have not checked the blend door yet but since the problem was front and rear I was looking for other issues.

Being an Eddie Bauer the truck has the automatic heating controls so I was first looking in that area, I found that the air conditioning is on when I have everything set to heat. I have the auto heat set to the highest temp and the ac is still engaged. The rear heater has the ac lines very cold. If I stop the truck hot and go into the store, when I start the truck the heat coming out is very hot however it slowly cools off. The ac is clearly causing a problem. Where do I start with this climate control system to repair it?

 

The A/C compressor runs whenever you have it set to automatic. Press the floor button and you'll get heat and the compressor will be off. As to the rest of the problem, to me it sounds like your heater cores need to be flushed.

 

The heating system was flushed by the previous owner not too long ago, and didn't seem to solve the problem. If the ac is on whenever it's set to auto is that not rather counter productive? I went out and set the heat to floor and the heat out of the front got warmer and the ac line in the rear were no longer cold. I will have to drive it longer on a cooler day to see if just having it on manual will solve my problems.
If I have it set on floor does the temp settings still affect the air temp coming out of the vents.
I don't get why the ac would be pumping cold air into the system while the heat is trying to pump hot air out. This is what seems to be happening.

Thanks for the reply, not trying to be difficult, just trying to understand the system.

 

Is there a schematic of the heating/cooling system somewhere online. I did a search but came up with nothing specific.

 

No problem...I'll try and explain how the automatic system works as simply as possible. When you're in auto mode the system has to be able to control the temperature inside the cabin. After all, if you set the temperature at 70 degrees you want it to be 70 degrees, right?

So one on one hand you have the heater core as the hot air source and on the other hand you need a cold air source to mix with the hot air source, hence the A/C compressor. Now the way the system automatically regulates the air temperature coming out of the vents is by moving what's called a blend door between the hot and cold air sources. Think of a single handle sink faucet, on one side is cold water and hot at the other. The desired temperature out of the faucet is established by moving the handle left and right until the correct cold and hot source mix is achieved. The blend door does this same function, only automatically. Therefore, if the A/C compressor wasn't running you wouldn't have a cold source so all you would get is heat, just like as if you had no cold water running to the sink faucet.

You might be asking yourself why not have the compressor cycle on and off as it's needed. The answer to that is, when the compressor is turned on it takes time for it to reach the correct pressure to make cold air, this would in turn cause the system to respond way to slow and maintaining the correct temperature would be sluggish and difficult.

 

I have a tread some where here for the same problem, I dont have auto climate control, 2001 expedition no heat, replaced thermostat flushed system, temp is good right in the middle, changed both blendair door motors cause they go bad alot, no difference. I have front and rear heat, in the winter I barley get any heat, blower works fine, i can hear the blend air door open and close, is it possible to have both heater cores blocked up? She dont drive much only has 65,500 miles on her. any ideas

 

I have similar issue with my 2010 expedition xlt. Have clicking in rear from what I think is blend door (not in front though). Ac is cold but could be colder but I have no heat whatsoever.

 

Yes, it sure does sound like you're having an issue with the motorized blend door actuator.

 

Yeah I figured that but what about the front? There's no heat anywhere and no clicking in front. Just in back.

 

Assuming you've felt the two heater hoses and they're hot when the engine is fully warmed up, you have two different issues. The rear clicking is due to a broken gear inside the motorized blend door actuator, the front can be the infamous broken blend door issue. When the blend door hinges break the door just lays there leaving you unable to control the front temperature.

 

I have a similair issue with my heat in my 2000 ford expedition. I had my intake manifold crack on my last year before the winter and I had gotten it fixed including replacing the temp gauge. Then I didnt have any heat. The line going into the heater core (Right Line) is really hot but yet the left side is cold. Wasnt to sure if just flushing the heater core will fix the issue. My A/C works just fine.

 

Definitely sounds plugged. I'd first try back flushing the core and if that doesn't work then you'll need to replace it.

 

I figured that might be the issue because when my intake manifold cracked all of my antifreeze got blown out of it, prolly has funk caught in it. Anyone have a link to a thread or video on how to back flush this? I know it isn't hard but I don't wanna flush water into the wrong area.

 

I have a 2000 Ford Expedition, XLT, 4WD, V8, 5.4 Liter.
I had front heater core bypassed, I just changed it, am re-assembling, but need diagram for where all hoses connect on block, etc.
Either post here or email to mesark@yahoo.com

Thanks,
Bill

 

I have a 1999 Eddie Bauer Expedition, 4WD, V8, 5.4 Liter with Auto Climate Control. I can try to send some pictures of the hoses it you still need them. Not sure if 1999 and 2000 are the same.