i have a 2000 f-150 XLT and i just noticed about a month back that im only getting cold air on all temps everywhere.im not sure if its the cold air from outside when its on heat or if it just stays on a/c or what. i have figured out its not the heater core,dont think its the temp **** on the panel.someone told me its probably te door that switches back and forth isn't opening or the motor is broke.well im pretty sure its not that either but how would i find out? so if anyone has any answers suggestions about what is wrong or any ideas?

 

On most cars there is a valve hooked nto the inlet hose to the heater core, when you put the **** on heat it opens the valve and lets hot water go through the heater core thus you are now producing heat. If you are sure it's not the **** then find the valve on some cars it's out side in the engine compartment I am not sure on ford trucks. some one should pipe in and let you know where it is. It may and probably is vaccum operated. hope this helps.

Lance

 

I am trying to remember if these are vacumn operated or not. The valve is on the right side of the engine compartement next to the firewall. You will see all the heater hoses and the valve in the middle of them.

 

Well when you find the valve have some one turn the heat switch from cold to hot and back see it it is operating. Sometimes the valves get corrosion and crud on them that stop them from operating dw40 or other lubricants will fix it with some work.

 

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The temperature blend door has an electronic actuator that opens and closes it to adjust the amount of airflow through the heater core. The actuator is under the center of the dash, above the hump in the floor, attached to the bottom of the heater housing.
I've seen the actuator go bad on these but the blend door where the actuator attaches to can break too. That's quite a common problem on Explorers and most of the info for them works on these trucks. Take a look at https://www.ford-trucks.com/forums/s...d.php?&t=24962

 

Racerguy if you would clarify for me, does the hot water always flow through heater core but just no air is allowed to flow across the core or is there a valve that actually stops the flow of hot water? Does the actuator door just control where the air flows to or actually stop all the air flow?

 

On these the hot water always flows through the heater core. The temperature blend door controls how much air flows through the core or around it.

 

I'm trying to get to https://www.ford-trucks.com/forums/s...ad.php?t=24962
but it says there is no thread specified. Can you help?

 

Welcome to the forum mthommes

It appears that maybe that thread isn't on the server anymore for some reason. I'm not sure what happened to it.

I assume you've got blend door problems on your truck? What year and model and what's it doing or not doing?

 

Hi Racerguy!

This is about my son's 1998 Mercury Mountaineer 5.0L which he bought a few months ago. A/C works great but when it got chilly, he realized he wasn't getting any heat. Thermostat's ok, water pump ok, good flow through the heater core. One strange thing beside no temp control is that it seems like when you put the function switch on anything besides "Off", the A/C comes on. We thought it might be the 3 switch module that that controls the heat/ac but then I started focusing on the blend door being stuck since he only gets cold air. He's had estimates of >$1000 to fix it, but he's not about to dump that kind of money into it. He's kind of in a bind because this was the vehicle he was using to take his dog to the dog park, but with no heat, the windows frost up and neither the 2-legged or 4-legged passengers are very comfortable or safe.

The quick fix I found at http://www.blenddoorfix.netfirms.com/ seems promising but I haven't had a chance to see what it looks accessing that area through the glovebox. Maybe this weekend. Any thoughts or hints are certainly appreciated. Thanks!

Mike

 

The most common cause of what you're describing is a broken blend door.
The quick fix you found will probably get it working again and the instructions there will show you how to access it to check it. It's a bit of a pain to check but not all that bad.
To replace the blend door if the quick fix doesn't work you have to remove the whole dash and heater plenum assembly
The only way you can get a blend door from Ford is to buy the whole heater plenum assembly.
You can get a replacement blend door seperately from Motormite. Do a search on www.dormanproducts.com for part number 76807.

The A/C does run in any position other than off or vent to help dehumidify the interior of the vehicle to help keep the windows clear.

 

I got the impression from the "quick fix" link that the part that breaks is the plastic post coming off the servo control motor, activated by the temperature switch position. That looks like it just mates with the top of the blend door axis post. Does the blend door really break such that it has to be replaced? That seems like a much tougher job, basically impossible without taking out the dash.


Mike

 

i had a similar problem... it was my ****... it broke free of the shaft and it just sliped on it and the shaft happend to be stuck on the cold side...

 

On the Explorer/Mountaineer the part that usually breaks is the top of the blend door shaft where the servo shaft goes into.