Thermostat

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Oct 13, 2002 | 01:31 PM

grandin

Thread Starter

New User

Joined: May 2002

Posts: 3

Likes: 0

From: Lebanon usa

Thermostat

I have a problem with the a/c & heat thermostat on my 1998 Navigator. It is one of those automatic controls...where the temperature is set by setting the desired temperature. It is stuck on cool....and when the temperature is run up to 90 degrees it still blows cold. It has the rear heat and air, and it will get hot when the rear temperature is turned up. I know on the older auto and less complicated there was a valve in the heater line that would get stuck sometimes. I looked under the hood but could find no such control valve in the heater line. I was hoping that the valve was stuck and would be easy to free up.....so my wife can have some heat..... Has anyone had this problem and can it be easily fixed?

Oct 14, 2002 | 11:28 AM

charlesvalentine

Senior User

Joined: Jan 2002

Posts: 176

Likes: 1

From: TEXAS!

Thermostat

I believe there is a blend door that is supposed to open to "blend" the hot and cold air. There are a few of these doors and they are elactronic motor controlled. In addition there are a few tempature sensors involved. There are DTCs associated with the failures of these components. So I would recommend getting a code scanner (or get the codes read) There should be DTCs that indicate the problem like : B1249 - Blend Door failure.

Then I would recommend getting the FORD CD from the Guy on Ebay who sells them for between $10-$20. The CD has indepth diag proceedures for determining root cause and instructions on how to replace the parts. Be forewarned that some of the tests they ask you to do require breakout boxes, multimeters and other special tools. But, through a little street smarts its easy to eliminate certain tests and being part of the problem.

99 F250SD EC 5.4L 3.73 285 BFG/ATs...
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