How do you repair the heater blend door on a 1997 Ford Expedition?

Answer 1

Typically to fix a broken blend door, a mechanic will disassemble the entire dash, and replace the plenum box. Unfortunately this is an expensive fix because it is labor and parts intensive. There is a DIY solution called heatertreater. They provide instructions on how to access the blend door by removing the glove box, and replacing the blend door without removing the dash and plenum assembly. Broken blend doors are a common problem among Ford Explorers, and most heating and A/C issues in late model Ford explorers and Expeditions are directly caused by a malfunctioning blend door.

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You can also try look here:

- http://www.ford-trucks.com/forums/192261-99-eddie-bauer-expedition-blend-door-fix.html

The heater core is difficult to change on the Ford trucks. They have it buried in the plenum box and you have to remove the steering wheel, steering column, dash, evacuate the refrigerant system, drain the radiator, and remove the plenum box to get to the core. Replacing the core is easy, getting to it is a day's work. The Expedition is particularly difficult to get to. It is almost above the transmission tunnel and well buried behind the dash. The Expedition uses the same plenum box as the F150, so any information on that system applies to the Expedition/Navigator.

You need to be sure that the heater core is really the problem before tackling this job. If you have a pool of coolant on the floor, you'll have to go after the core. If the problem is lack of heat, there are some things you need to eliminate before tearing into the truck. You need to make sure that coolant is flowing through the core. Check the temperature of the heater hoses going into the firewall when the engine is cool and see if they warm up together as the engine warms up. If both hoses get hot at about the same rate, this is a good indication that coolant is flowing through the core. You can also remove the hoses and flush the core with a water hose splice from Home Depot and a water hose. Water should flow unobstructed through the core.

If it appears that coolant is flowing and you don't have obvious leaks, the next step is to check the blend door. This door controls the air flow through the heater core and failure is common on Ford trucks. When the door breaks, it can block the flow of air through the core and kill heat and will also have an impact on AC. If the system seems to work intermittently, it's a good indication that the door is broken and rattling around randomly blocking or opening the passage to the core.

For diagnostic information on how to check the operation of the blend door and a cheap easy fix, check the heatertreater listing on Ebay or the web site at heatertreater.net. The dealer fix for the blend door is basically the same procedure for replacing the heater core, so it will be expensive. The HeaterTreater alternative will solve the problem at a fraction of the cost and work and is well within the capability of the average shade tree mechanic.That is why Aluminum blend doors, recirculation doors and modes doors would be preferred over the plastic OEM blend doors.