Heat for 04 Expedition

[chasineyes]

Last night I let the truck "warm up" for about 15 minutes and noticed it wasn't really producing much heat. Even after driving, the air was "warm" but not as hot as I thought it should be. If I remember right, the thermostat helps control the temperature of your interior heat? Can a thermostat go "partially bad" or do they pretty much just die out?

Thanks and happy new year.

By the way the truck has 103000 and probably never had it changed. And the trucks temperature reading seems to work like normal.

[zamboni]

Sounds like the thermostats shot. Probably stuck. When you get a new one, ask for the "hottest" one they have

[Macgyver55]

Quote:

the thermostat helps control the temperature of your interior heat

Not really, it only regulates the temperature of your engine. But, when the thermostat is operating correctly, the engine temp will more quickly get to where it should be and you will have more heat than if it never reaches full operating temp. A sticking or partially stuck stat will cause a slower warm up than a properly functioning one will, and sometimes/often never reach full running temp.

Make sure to verify that the coolant level is full before doing anything, and if and when you put in a thermostat, put in the same as you take out.

[fishing tech]

A couple of things can cause no heat or poor heat. T stat is 1, plugged heater core is 2, and a broken blend door or temp control unit if you have auto temp control.

Away to check the stat is to start the vehicle, let it run and watch your temp gauge. Once the gauge starts to move into the normal range feel the upper radiator hose. If it is warm odds are your stat is opening early or staying open. When the temp gauge reaches its highest point in the normal range the upper rad hose should be to hot to hold onto. If it is to hot to hold onto at this time check the core.

To check the heater core. Once the temp gauge is into the normal range you can feel the heater hoses going into and coming out of the core. They should both be very hot, the outlet will be a tad cooler but you should not be able to hold onto very long. This will tell you if the core is plugged or not. If the inlet is hot and the outlet is cool the core could be plugged. If they are both hot to the touch and you have no/poor heat you may have a blend door. blend door motor, or controller problem.

I hope this helps.

[mechanico]

If it's not the thermostat, and it's probably not, there's a thing called a blend door in the climate control. All that stuff is burried deep in the dash board. It's vacuume controlled, so... First check for old cracked vacuume hoses that you can get to. Also the climate control module can go bad, or connections can get loose. It is what the heat, vent, and fan knobs are attached to. There is a really nifty vacuume plug in the thing which can come loose, but not likely. Your best bet to get a handle on it is to google "blend door" with your modle and year. Lotsa times folks include pics and step by step instructions. I hope I'm wrong about it, cause it's a real pain to get to.

Good luck!

[chasineyes]

Thanks for the help. I don't think its the thermostat but haven't had a chance to "feel" the radiator hoses to potentially eliminate that. With regards to the "blend door", would a faulty one cause water to drip from the box/area under the glove box? We notice in the summer if we're on a long drive in hot conditions, water will start dripping from that area?

[Macgyver55]

If it is plain water (not coolant) dripping inside during warm weather, it means the condensor drain is plugged.

Its possible that if there were any water remaining from the summer, that the blend door could be frozen and may thaw out after driving, or it may have broken from being forced by the actuator.

It would be a good idea to get it in a warm place to thaw completely, then make sure that drain is open.

[mechanico]

I think McGyver55 may be right about the drain plug or it could also be that the heater core is plugged and/or leaking, which could also explaine the lack of heat. Actually, you can access part of the plenum box that houses the heater core, blend door, and maybe part of the cooling condenser as well as fan ducts by pulling the glove box out. I can't specifically remember, but I believe you can see some vacuume hoses from there too. Also, I use a mirror a lot for these kind of repairs...'takes a little practice...

Also! Back on McGyvr's idea, if you're not sure what is leaking, taste it. If it's sweet it's coolant AND you need to spit it out quickly cause it's poison. Ok, you won't immideately drop dead, but you should probably rinse...it'll sure kill a dog.

[jeffreyd]

you can clean the drain tube by crawling under the passenger side behind the front tire and look in the area where the core is. it should be a tube in the body work that has a anti dirt plug in the end. if you can get to it pull the plug out and blow shop air in the tube to clean it out.

[mechanico]

Just a little air pressure. You can pop the hose loose. Don't make me tell you how much trouble I caused when I tried to clear out the tub drain like that...

[mechanico]

Did ya ever figure it out?