2002 Explorer - Assistance request - Heat is not working

[STLMach1]

2002 Explorer - FIXED - Heat is now working!

Greetings folks,

I bought a 2002 Ford Explorer Limited back in February of this year. The heat worked well during late winter/early spring but now that it's cooling off again and I'm turning it back on for the first time in a while to find that it's blowing cold air rather than warm.

It has the climate control feature that allows you to set a desired temperature rather than manually turning a temp control dial. I believe that the controlling unit knows what it is trying to do (meaning it's trying to heat) as when I run the temp down to its lowest setting (60 degrees), the blower fan will virtually shuts off. With the cab temperature being cooler it knows that it doesn't need to add any air. When I run it up to its max temperature (90 degrees), the blower progressively increases in speed attempting to warm the interior. The problem seems to be that the engine coolant may not be making it into the heater core to provide a heat source.

Even when I try manipulating the temperature through manual controls rather than running it in Auto mode I essentially get the same results. When transitioning settings, every now and then I'll feel some heat but it quickly fades back to cold air.

Oddly, when I've got it set to 90 degrees in Auto mode and switch to manual (say the vents), the A/C light comes on giving me them impression that despite being set at 90 degrees when in Auto, that mode was in fact running the A/C. Is this a possibility? How can you truly tell when the compressor is engaged (i.e. cooling) and not just free spinning (i.e. not cooling)?

I recall there being a valve in the coolant lines somewhere between the radiator and the heater core that would stop the flow of hot water when you weren't adding heat to the incoming air. Is this still present on the 2002 Explorer and could this be the issue? I seem to recall this having been a problem on a 1986 Bronco II that I owned years ago.

I also recall there being a door in the heating/cooling duct work that might play a part in the air source (hot or cold) coming into the cab. Might this be somehow inoperable (vacuum driven?) or possibly stuck?

Could there be relays involved in all of this that aren't working or worse, something wrong with the temperature controlling unit essentially issuing incorrect directions to the devices it manipulates when regulating temperatures?

This is a little out of my element so any direction that you can provide would be MOST appreciated.

Thanks,
Michael

 

[Exproblems]

Greetings folks,

I also recall there being a door in the heating/cooling duct work that might play a part in the air source (hot or cold) coming into the cab. Might this be somehow inoperable (vacuum driven?) or possibly stuck?

This is a little out of my element so any direction that you can provide would be MOST appreciated.

Thanks,
Michael

>>>>>>>>>>>>>>>>>

Try this link below to a post by "Curtis". It refers to a problem with the "air recirculation door".

http://www.explorerforum.com/forums/showthread.php?t=284042

You could also have a problem with the "Blend Door actuator" which controls the cold and hot air mixture into the vehicle. The actuator is the motor that rotates the blend door from the hot and cold side of the system. Do you hear any kind of thumping noise coming from behind the dashboard when you adjust the hot and cold temp knob manually? If you do hear the thumping or clunking noise, then your blend door actuator is bad. There is a post on how to fix this written by "BigRondo" on the 1st page of the forum Sticky Threads for Stock 2002-2005 Explorers. I got that post link for you on blend door actuators from BigRondo, it's below.

http://www.explorerforum.com/forums/showthread.php?t=294140

Both issues are common problems in 2002-2005 Explorers.

 

[STLMach1]

Thanks, Exproblems!

I will look at these posts tonight and see if they might point to the problem. I test drove another 2003 Explorer that made the telltale thumping noise so I know what you're talking about. Mine isn't making that sound. I'm pretty sure that I can hear the blend door moving when swinging the temperature. Not sure yet if that's the culprit or not but it's worth looking into.

I will update with my findings asap.

Thanks again!
Michael

 

[Exproblems]

Thanks, Exproblems!

I will look at these posts tonight and see if they might point to the problem. I test drove another 2003 Explorer that made the telltale thumping noise so I know what you're talking about. Mine isn't making that sound. I'm pretty sure that I can hear the blend door moving when swinging the temperature. Not sure yet if that's the culprit or not but it's worth looking into.

I will update with my findings asap.

Thanks again!
Michael

>>>>>>>>>>>>>>>>>>>>

Your welcome! Besides the blend door actuator going bad, the blend door itself can go bad as well, just not as common as the actuator going bad. There is a fix for it called "heater treater". Try typing "heater treater" into the search bar at the top of the forum and it should pull up posts on bad blend doors. Good luck!

 

[STLMach1]

I've done a bit more research regarding the posts concerning the blend door and the actuator. Sounds like the actuator repair is going to a FUN project. Before I dive into that however I wanted to pose a few more questions along with some shots.

When I cycle the temp control, I can hear what I'm certain is the blend door changing positions which really leads me to believe that the root cause of this is elsewhere (though at this point it's too early to tell). I'm just hoping to find an easier fix than pulling the dash apart if at all possible.

While I'm not exactly certain of the valve's name, I believe that the value pictured below is what regulates the flow of hot water to the heater core. When I switch the temp from hot to cold, this valve does not change position. Should it?

I would expect the line to be hot but it's not. I've even manually held the valve in the other position hoping that water would begin to flow but the air coming from the heater vent still heat up nor does the line itself.

There's what appears to be a filter just above the fitting that connects to hose to the top of the intake manifold. Could this be clogged? The manifold's hot but the line that should be receiving water from it is not.

It puzzles me that the line's not hot. If the blend door or the actuator motor were the problem, wouldn't these lines that lead to the heater core, especially where the lines are metal, still be hot?

Many thanks for the input folks!
Michael

 

[STLMach1]

And it's fixed! - I have heat again!

Well, embarassingly enough, I found the cause: Low Engine Coolant Level.

I didn't even think to check this until tonight but the radiator must have been low. I added coolant and took it for a test drive to find that I once again had heat. Thankfully a cheap and easy fix. Just frustrated that I didn't think of that sooner...

Thanks again for the input Exproblems!
Michael

 

[Fighting5thSVT]

Don't be embarassed, be happy. Cheap and easy with no worries. Be glad you found it now than after tearing your dash and fingers to pieces.

 

[Exproblems]

Well, embarassingly enough, I found the cause: Low Engine Coolant Level.

I didn't even think to check this until tonight but the radiator must have been low. I added coolant and took it for a test drive to find that I once again had heat. Thankfully a cheap and easy fix. Just frustrated that I didn't think of that sooner...

Thanks again for the input Exproblems!
Michael

>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Your welcome Mike! Glad it was an easy fix. How much coolant did you have to add to bring it up to the full level? Now you just have to find out what was the reason for the cooling system to be low on coolant in the first place. Make sure you don't have any leaks anywhere.

 

[STLMach1]

Finally found the leak...

Well, what I thought was an easy fix turns out to not be so easy... After just buying the Explorer earlier this year I thought that maybe the coolant had been low all along.

Turns out the leak is at the gasket between the aluminum thermostat housing and the plastic intake manifold shown by arrow A.

I had hoped that I could just take the aluminum thermostat housing off but arrows B1 and B2 (which can't been seen in the photo) are to two bolts that go from the bottom up rather than the top down. There appears to be NO way to get to bolt B2 without removing the entire intake manifold.

Ford tells me that the gasket that is under the thermostat housing is sold only as part of a kit which includes an entire intake manifold for roughly $600. Expensive gasket... I've found assemblies like the one in the photo online for under $200. Think Ford's marking this up a bit???

Does anyone have any suggestions as to the best way to fix this? I will try to take some pics of my intake on Sunday to better illustrate the problems. Thanks in advance for any input that anyone can lend.

After some searching, it sounds like this could be my issue too. https://www.explorerforum.comforums/showthread.php?t=262363

What concerns me now is the fact that the aluminum crossover is meant to be part of the plastic intake manifold and that if this is the source of the leak that there may be no separately sold gasket that can be replaced. I guess that this would be separate from the intake manifold gaskets... Sounds more like the entire manifold would need to be replaced just to replace this gasket. Wonder of one could made from gasket material with an Exacto knife. Any more input on the seal(s) between the aluminum crossover and the plastic intake?

Michael