When I back flushed mine a couple of weeks ago, I disconnected the hoses at the front of the engine block (near the thermostat) they were just held on by spring clips. Worked great!

 

Thanks for the input. I'll look again. Probably missed seeing the connections.

I do have one other question for anyone who has removed and or replace the blend door actuator. Better yet, if you have one accessible.

With the Blend Door exposed, can you or should you be able to turn the shaft of the actuator by hand?

I know they are electrically operated but mine will not move by hand. I am going to remove and replace along with blend door but curios.

 

I would not put much pressure on it as you might strip the plastic gears. My neighbor just did his and that was the problem, stripped gears.

 

I took the dash off and checked the heater core, blend door, and blend door actuator. Everything seems OK so started looking in the engine compartment.

Found:

1. Found a bad very short vacuum line and replaced.
2. Checked both heater hoses and they are luke warm.
3. Checked upper radiator hose and it is luke warm and has next to no pressure.

I don't remember what the lack of pressure in the upper radiator hose means, i.e. water pump or thermostat.

I am thinking that the thermostat is bad and stuck in the open position.

Need help or ideas.

Thanks

 

My answers are in blue. Keep checking.

 

This thread is well-timed. I am deep into this on my 99 Expy with manual HVAC. Hopefully a lot of people are watching this thread and a solution can be found. I have the 4.6 engine and that is apparently plumbed in a very different way to the larger 5.4 engine. I had been getting a smidget of heat out of the front. If the fan is on lo, then there's a touch of heat. Raise the fan level and no heat. I am sure that's because there is a trickle of water through the heater core. The core is not clogged, as I had it checked with this problem first started, and there is a little more heat out of the rear unit, but that's it. Now, here is the interesting part... I thought it would be the blend door (as you are probably thinking), so I pulled the console and the actuator. No broken parts whatsoever. Actuator is good. I tested it. I put a piece of cut metal in the bottom of the blend door and moved it by hand without an issue. Open, closed. Smooth. All the splines are intact. I can see how these break because the control resistance range goes beyond the physical range of the door, so if you want yours to last, don't turn it all the way to cold or all the way to hot. That is what puts the pressure on the blend door. Moving on, I checked the hoses with the engine cold. They are empty. I do not think this is normal. The radiator tank is full. So, my thoughts turn to a shutoff valve. On the 5.4, there is a valve on the heater supply which shuts off when AC is turned on. This would be my prime suspect, BUT, I don't see one - anywhere. Unfortunately, on the 4.6, the heater supply looks like it is coming from the back of the engine. One line is on a pipe from the intake manifold. Can't find the other too easily yet. Does anyone know if there is one of these valves on the 4.6? If so, where it might be located? Also, is it possible that there could be an air bubble in the system? Any other thoughts? There are times when going up and down hills, the heat works normally, so when the water gets in there, we're good to go, but it doesn't seem to be getting there. As far as this thread goes, I suspect the shutoff valve and I would say the same for me - if I could verify that it has one and get the location! I'm the original owner, so if the part is supposed to be there, it should still be there. Thanks in advance for any help!

 

It seems like you have some air in the system and it needs to be purged.

SECTION 303-03: Engine Cooling 2000 Expedition/Navigator Workshop Manual

GENERAL PROCEDURES

--------------------------------------------------------------------------------

Cooling System Draining, Filling and Bleeding
Draining

WARNING: Never remove the pressure relief cap while the engine is operating or when the cooling system is hot. Failure to follow these instructions can result in damage to the cooling system or engine. To avoid having scalding hot coolant or steam blow out of the degas bottle when removing the pressure relief cap, wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, (still with a cloth) turn and remove the pressure relief cap. Failure to follow these instructions may result in personal injury.

CAUTION: The coolant must be recovered in a suitable, clean container for reuse. If the coolant is contaminated it must be recycled or disposed of correctly.

NOTE: About 80% of coolant capacity can be recovered with the engine in the vehicle. Dirty, rusty or contaminated coolant requires replacement.

Release the pressure in the cooling system by slowly turning the pressure relief cap one half turn counterclockwise. When the pressure is released, remove the pressure relief cap.
Place a suitable container below the radiator draincock (8115). If equipped, disconnect the coolant return hose at the oil cooler.
Open the radiator draincock.
Close the radiator draincock when finished.
Filling

Add the correct engine coolant mixture to the degas bottle.
Move the temperature blend selector to the full warm position.
Run the engine until it reaches operating temperature.
Add the correct engine coolant mixture to the degas bottle until the coolant level is between the "COOLANT FILL LEVEL" marks.
Turn off the engine and allow the cooling system to cool.
Repeat Steps 1 through 5 until the degas bottle level is OK.
Bleeding

Select maximum heater temperature and blower motor speed settings. Position control to discharge air at A/C vents in the instrument panel (04320).
Start engine and allow to idle. While engine is idling, feel for hot air at A/C vents.
CAUTION: If the air discharge remains cool and the engine coolant temperature gauge does not move, the engine coolant level is low in the engine and must be filled. Stop the engine, allow to cool and fill the cooling system as described.

Start the engine and allow to idle until normal operating temperature is reached. Hot air should discharge from the A/C vents. The engine coolant temperature gauge should maintain a stabilized reading in the middle of the NORMAL range and the upper radiator hose (8260) should feel hot to the touch.
Shut the engine off and allow it to cool.
Check the engine for coolant leaks.
Check the engine coolant level in the degas bottle and fill as necessary. For additional information, refer to Cooling System Draining, Filling and Bleeding in this section.

 

Thanks for that. I thought it might be the issue, but I went back out and did more research. Looks like there is a clog at one of the connectors in the pipe going to the rear unit. This may be disrupting the flow for front and rear. Not knowing how the circulation is setup, all I can know for sure is that all is hot except for this one connector. Hot on the pipe side, cool on the hose side. Here is the link to another thread I found where someone has what I think is exactly the same issue. https://www.ford-trucks.com/forums/1...r-vents-2.html

 

So what is the problem if you have done all of that and still have no heat? I have a 99' with the 4.6 and am
at my wits end as to what to do next. I have replaced thermostat (changed to a
hotter one), changed water pump, flushed system 3 to 4 times, heater core has been
burped and has proper flow (just no heat). Checked the blend door, actuator motor,
replaced temp. control, checked vacuum lines (used vacuum tester inside the cab and
under the hood). Top heater hose from radiator checks at 110 degrees after 40 mile
trip and bottom runs around 88 degree. When you park after a trip you can touch the
block and hoses without being burned. _The block __will not heat up._ I am at my
wits end with this truck I even went as far as putting cardboard in front of the
radiator to check the fan clutch and it still runs cold! Still banging my head! Please, any ideas welcome!!

 

Sounds like my situation and given up on banging head. Yesterday drove the car for quite awhile and checked upper radiator hose. I had pressure unlike earlier. I still did not have heat.

My daughters emergency brake light is staying on for some reason and intermittently goes out. On my way home, the light went out and started having heat front and rear. Not a lot of heat but it was warm enough that you could tell the difference. I also noticed that the rear defroster on/off light was blinking. Shut the car off and determined that a relay was clicking so I need to change it but busy this morning. Son diagnosed with Terminal Cancer and going to Stanford Doctor for Second Opinion this AM.

The heat at this point is the least of my problems however, based on the brake light issue and the multiple solutions offered that are not working, I am beginning to think that there is a computer issue. Not sure what but how can the brake light affect the heater unless tied to the computer somehow. If I solve the brake light and rear defroster clicking tomorrow when I return and it solves the heater problem, maybe this will take off in another direction.

Sorry, starting to vent. On top of everything else, my daughter was hit by a drunk driver a few days ago in my 2004 Expedition with 60K miles. The car is borderline total and I won't know for sure for a couple more days.

 

You sure put what is important in perspective. I hope things improve for you and your family. We'll pray for their health to be restored.

 

Sorry to hear of the problems you and your family are facing and I certainly hope things get better for you all. I was at stage 4 myself about 8 years ago and hopefully your son will be as lucky as I was. A second opinion is a definate need when facing the few options that are available.

Moving on to your heat issues. Have you checked for or noticed any sign of a water leak from the windshield on the driver's side? As both you and developer have similar issues and have different climates, I am guessing that perhaps water may have gotten into the fusepanel and or the GEM that is directly above it. Believe me this is only a guess bur wierd actions from the E brake lamp combined with a sudden influx of more heat has me thinking that there may be an issue in that area. There is another part that could be causing the problem and that is the ambient air temperature sensor that is inside the head or control panel and may be obstructed.

SECTION 412-00: Climate Control System — General Information 2000 Expedition/Navigator Workshop Manual

DESCRIPTION AND OPERATION

--------------------------------------------------------------------------------

Climate Control System
WARNING: To avoid accidental deployment and possible injury, the air bag system backup power supply must be depleted before repairing any climate control components. To deplete the backup power supply, disconnect the battery positive cable and wait one minute. Failure to follow these instructions may result in personal injury.

WARNING: Carbon monoxide is colorless, odorless and dangerous. If it is necessary to operate the engine with vehicle in a closed area such as a garage, always use an exhaust collector to vent the exhaust gases outside the closed area. Failure to follow these instructions may result in personal injury.

WARNING: R-134a is classified as a safe refrigerant, but misuse can make it dangerous. The following precautions must be observed. Failure to follow these instructions may result in personal injury.

Always wear safety goggles when repairing an air conditioning system.
Avoid contact with liquid Refrigerant R-134a. R-134a vaporizes at approximately -25°C (-13°F) under atmospheric pressure and it will freeze skin tissue.
Never allow Refrigerant R-134a gas to escape in quantity in an occupied space. R-134a is non-toxic, but it will displace the oxygen needed to support life.
Never use a torch in an atmosphere containing R-134a gas. R-134a is non-toxic at all normal conditions, but when it is exposed to high temperatures, such as a torch flame, it decomposes. During decomposition it releases irritating and toxic gases (as described in the MSDS sheet from the manufacturer). Decomposition products are hydrofluoric acid, carbon dioxide and water.
Do not allow any portion of the charged air conditioning system to become too hot. The pressure in an air conditioning system rises as the temperature rises and temperatures of approximately 85°C (185°F) can be dangerous.
Allow the engine to cool sufficiently prior to performing maintenance or serious burns and injury can occur.

CAUTION: To avoid damaging the vehicle or A/C components, the following precautions must be observed:

The A/C refrigerant of all vehicles must be identified and analyzed prior to refrigerant charging. Failure to due so can contaminate the shop bulk refrigerant and other vehicles.
Do not add R-12 refrigerant to an A/C system that requires the use of R-134a refrigerant. These two types of refrigerant must never be mixed. Doing so can damage the A/C system.
Charge the A/C system with the engine running only at the low-pressure side to prevent refrigerant slugging from damaging the A/C compressor.
Use only R-134a refrigerant. Due to environmental concerns, when the air conditioning system is drained, the refrigerant must be collected using refrigerant recovery/recycling equipment. Federal law requires that R-134a be recovered into appropriate equipment and the process be conducted by qualified technicians who have been certified by an approved organization, such as MACS, ASI, etc. Use of a recovery machine dedicated to R-134a is necessary to reduce the possibility of oil and refrigerant incompatibility concerns. Refer to the instructions provided by the equipment manufacturer when removing refrigerant from or charging the air conditioning system.
Refrigerant R-134a must not be mixed with air for leak testing or used with air for any other purpose above atmospheric pressure. R-134a is combustible when mixed with high concentrations of air and higher pressures.
A number of manufacturers are producing refrigerant products that are described as direct substitutes for Refrigerant R-134a. The use of any unauthorized substitute refrigerant can severely damage the A/C components. If repair is required, use only new or recycled Refrigerant R-134a.

CAUTION: To avoid contamination of the A/C system:

Never open or loosen a connection before discharging the system.
When loosening a connection, if any residual pressure is evident, allow it to leak out before opening the fitting.
Evacuate a system that has been opened to install a component or one that has discharged through leakage before charging.
Seal open fitting with a cap or plug immediately after disconnecting a component from the system.
Clean the outside of the fittings thoroughly before disconnecting a component from the system.
Do not remove the sealing caps from a new component until ready to install.
Refrigerant oil will absorb moisture from the atmosphere if left uncapped. Do not open an oil container until ready to use, and install the cap immediately after using. Store the oil in a clean, moisture-free container.
Install a new O-ring seal before connecting an open fitting. Coat the fitting and O-ring seal with refrigerant oil before connecting.
When installing a refrigerant line, avoid sharp bends. Position the line away from the exhaust or any sharp edges that can chafe the line.
Tighten threaded fittings only to specifications. The steel and aluminum fittings used in the refrigerant system will not tolerate overtightening.
When disconnecting a fitting, use a wrench on both halves of the fitting to prevent twisting of the refrigerant lines or tubes.
Do not open a refrigerant system or uncap a replacement component unless it is as close as possible to room temperature. This will prevent condensation from forming inside a component that is cooler than the surrounding air.

The manual climate control system heats or cools the vehicle depending on the function selector switch position and the temperature selected.

The function selector switch position determines heating or cooling and air distribution.
The temperature control setting determines the air temperature.
The heater blower motor switch (18578) varies the blower motor speed.
The electronic automatic temperature control system maintains the selected vehicle interior temperature by heating or cooling the air.

During A/C operation the system also reduces the relative humidity of the air.
The driver may override the automatic mode of operation.

Principles of Operation

There are four main principles involved with the basic theory of operation:

Heat transfer
Latent heat of vaporization
Relative humidity
Effects of pressure
Heat Transfer

If two substances of different temperature are placed near each other, the heat in the warmer substance will transfer to the colder substance.

Latent Heat of Vaporization

When a liquid boils (converts to gas) it absorbs heat without raising the temperature of the resulting gas. When the gas condenses (converts back to a liquid), it gives off heat without lowering the temperature of the resulting liquid.

Relative Humidity

The amount of moisture (water vapor content) that the air can hold is directly related to the air temperature. The more heat there is in the air, the more moisture the air can hold. The lower the moisture content in the air, the more comfortable you feel. Removing moisture from the air lowers its relative humidity and improves personal comfort.

Effects of Pressure on Boiling or Condensation

As the pressure is increased on a liquid, the temperature at which the liquid boils (converts to gas) also increases. Conversely, when the pressure on a liquid is reduced, its boiling point is also reduced. When in the gas state, an increase in pressure causes an increase in temperature, while a decrease in pressure will decrease the temperature of the gas.

The Refrigerant Cycle

During stabilized conditions (air conditioning system shutdown), the refrigerant is in a vaporized state and pressures are equal throughout the system. When the A/C compressor is in operation it increases pressure on the refrigerant vapor raising its temperature. The high-pressure and high-temperature vapor is then released into the top of the A/C condenser core.

The A/C condenser core, being close to ambient temperature, causes the refrigerant vapor to condense into a liquid when heat is removed from the refrigerant by ambient air passing over the fins and tubing. The now liquid refrigerant, still at high pressure, exits from the bottom of the A/C condenser core and enters the inlet side of the A/C evaporator core orifice.

The A/C evaporator core orifice is the restriction in the refrigerant system that creates the high pressure buildup in the A/C condenser core and separates the high and low pressure sides of the A/C system. As the liquid refrigerant leaves this restriction, its pressure and boiling point are reduced.

The liquid refrigerant is now at its lowest pressure and temperature. As it passes through the A/C evaporator core, it absorbs heat from the passenger compartment airflow passing over the plate/fin sections of the A/C evaporator core. This addition of heat causes the refrigerant to boil (convert to gas). The now cooler passenger compartment air can no longer support the same humidity level of the warmer air and this excess moisture condenses on the exterior of the evaporator coils and fins and drains outside the vehicle.

The suction accumulator/drier is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the evaporator core from reaching the A/C compressor. The A/C compressor is designed to pump refrigerant vapor only, as liquid refrigerant will not compress and can damage the A/C compressor.

The refrigerant cycle is now repeated with the A/C compressor again increasing the pressure and temperature of the refrigerant.

The A/C cycling switch interrupts compressor operation before the external temperature of the A/C evaporator core gets low enough to cause the condensed water vapor (excess humidity) to turn to ice. It does this by monitoring low side line pressure. It is known that a refrigerant pressure of approximately 210 kPa (30 psi) will yield an operating temperature of 0°C (32°F). The A/C cycling switch controls system operation in an effort to maintain this temperature.

The high side line pressure is also monitored so that A/C compressor operation can be interrupted if system pressure becomes too high.

The A/C compressor relief valve will open and vent refrigerant to relieve unusually high system pressure.

Clutch Cycling Orifice Tube Type Refrigerant System

Item Part Number Description
1 19E762 A/C charge valve port (low side)
2 19E561 A/C cycling switch
3 19C836 Suction accumulator/drier
4 19703 A/C compressor
5 19D644 A/C compressor pressure relief valve
6 19D594 A/C pressure cut-off switch
7 19E762 A/C charge valve port (high side)
8 19712 A/C condenser core
9 19D990 A/C evaporator core orifice
10 19860 A/C evaporator core
11 — Low pressure vapor
12 — High pressure vapor
13 — Low pressure liquid
14 — High pressure liquid


System Airflow Description

Max A/C


When MAX A/C is selected:

The air inlet duct door is at full vacuum, closing off outside air and admitting only recirculated air.
The panel/defrost door is at full vacuum and the floor/panel door is in the no vacuum position, directing airflow to the instrument panel A/C register (19893).
The temperature is usually set for maximum cold but may be heated if desired.
Air will be picked up at the recirc opening by the blower motor (18527). Within the A/C control set for maximum cold, airflow across the A/C evaporator core (19860) will be diverted past the heater core (18476) and then directed into the passenger compartment through the instrument panel A/C register. There is also some airflow to the AC side window demisters.
The A/C compressor (19703) will be enabled when MAX A/C is selected.
The blower motor is on.
A/C


When A/C is selected:

The air inlet duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
The panel/defrost door is at full vacuum and the floor/panel door is in the no vacuum position, directing airflow to the instrument panel A/C registers.
The temperature may be raised if desired.
The A/C compressor will be enabled when A/C is selected.
The blower motor is on.
Vent


When VENT is selected:

The air inlet duct door, with no vacuum being applied, will block recirculated air and admit outside air. From there, air flows through the system to the instrument panel A/C registers.
The floor/panel door is in the no vacuum position to block airflow to the heater outlet floor duct (18C433).
The panel/defrost door is at full vacuum, closing off airflow to the windshield defroster hose nozzle (18490). There is also some airflow to the A/C side window demisters.
The temperature can be adjusted to heat the air but air cannot be cooled below outside temperature.
The A/C compressor will be disabled when VENT is selected.
The blower motor is on.
OFF


When OFF is selected:

The A/C inlet duct door is at full vacuum, closing off outside air and admitting only recirculated air.
The panel/defrost door is in the no vacuum position, closing the passage to the instrument panel A/C registers.
The floor/panel door is at full vacuum, closing the passages to the panel/defrost outlets.
The blower motor and the A/C compressor are off.
PANEL/FLOOR


When PANEL/FLOOR is selected:

The air inlet duct door is at no vacuum, blocking the recirculated air passage and admitting outside air.
The panel/defrost door is at full vacuum, closing off airflow to the windshield defroster hose nozzle.
The floor/panel door is in the partial vacuum position, allowing airflow to both the heater outlet floor duct and the instrument panel A/C registers. There is also some airflow to the A/C side window demisters.
The A/C compressor will be enabled when PANEL/FLOOR is selected.
The blower motor is on.
FLOOR


When FLOOR is selected:

The air inlet duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
The floor/panel door is in the full vacuum position, directing all airflow to the heater outlet floor duct.
The temperature can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature level.
The panel/defrost door is in the no vacuum position, blocking air circulation to the instrument panel A/C registers.
The A/C compressor will be disabled when FLOOR is selected.
The blower motor is on.
FLOOR/DEFROST


When the FLOOR/DEFROST is selected:

The air inlet duct door is in the no vacuum position blocking recirculated air and admitting outside air.
The panel/defrost door is in the no vacuum position directing airflow to the windshield defroster hose nozzle.
The floor/panel door is in the partial vacuum position, allowing airflow to both the windshield defroster hose nozzle and the heater outlet floor duct. There is also some airflow to the A/C side window demisters.
The A/C compressor will be enabled when FLOOR/DEFROST is selected to dehumidify the air and reduce windshield fogging.
The blower motor is on.
DEFROST


When DEFROST is selected:

The air inlet door is in the no vacuum position, admitting outside air.
Both the panel/defrost door and the floor/panel door are in the no vacuum position so that most of the incoming air is directed to the windshield defroster hose nozzle. There is also airflow to the A/C side window demisters.
The temperature setting will determine the amount of air that is directed through the heater core and the amount that bypasses the heater core.
The A/C compressor will be enabled when DEFROST is selected to dehumidify the air and reduce windshield fogging.
The blower motor is on.
Manual A/C Electrical Components

Item Part Number Description
1 19980 Manual A/C control assembly
2 19D594 A/C pressure cut-off switch
3 19E561 A/C cycling switch
4 19703 A/C compressor
5 18527 Blower motor
6 18591 Heater blower motor switch resistor
7 19E616 A/C electronic door actuator motor

Electronic Automatic Temperature Control Electrical Components

Item Part Number Description
1 — Remote control buttons
2 19D888 Automatic temperature control sensor hose and elbow
3 19E663 A/C sunload sensor
4 19E702 A/C ambient air temperature sensor and bracket
5 19980 Electronic automatic temperature control module
6 19D594 A/C pressure cut-off switch
7 19E561 A/C cycling switch
8 19703 A/C compressor
9 18527 Blower motor
10 19E624 A/C blower motor speed control
11 19E616 A/C electronic door actuator motor

 

I am sorry to hear about the way things are going for you and your family Vietnamvet. I pray things change for you and your family, my heart goes out to you. In case no one has told you this but "Thank you" for your service to our country.
Now back to the other two more days of working on same old thing and tired of not having heat!!! I have done everything possible and still have gotten nowhere! I have signed on to 3 different forums and still no answers. The best answer to my heat problem is looking like a wick and a match, at least it will be warm for a little while. Not real impressed with a 4.6 at all.

 

The 4.6 is a good engine depending on the application. I think it is definately underpowered for use in a 6000 lb truck without the addition of a blower or turbo.
Oh, and you forgot a gallon of gas.

 

Just reviving this thread a bit with what I think is new info. The 4.6 in my 99 is plumbed differently that the larger engine. The rear heat unit is plumbed with exactly the same diameter pipe as the front and the supply and return lines are joined with "T" connectors. I spent a lot of time chasing down a low-front-heat issue thinking it was the diverter door or servo, which it was not. The problem is when there is the slightest restriction in the front heater core (even some buildup as I have), the volume of hot water runs to the rear heater core instead. To get heat to come back to the front as a fix, the supply out to the rear heater core needs to be throttled down with a restriction. In my case, a clamp. By impeding the flow a bit to the rear core, heat improved 100% out of the front. My .02 - YMMV.