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2002 Sport - No Heat


deek33

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Indianapolis, Indiana
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2002 Explorer Sport 4x4
I drive a 2002 Explorer Sport and unfortunately the heat stopped pumping out at the end of last winter. The blower would shut off and turn back on whenever it pleased, completely at random.

Summertime came around and after a charge the a/c was rockin'. No issues.

Fast-forward to now. The blower doesn't seem to shut itself off anymore, but I still have no heat. I've replaced the thermostat and flushed the cooling system. I also disconnected the hoses from the heater core and shot some water through, which seemed to flow just fine.

The hose going in to the heater core gets very hot, but the one coming out seems to only get a little warm. Is this normal?

Also, not sure if this is normal, but even with the heat control knob turned to high my a/c clutch engages every 10-20 seconds.

Any suggestions? My soon-to-be frozen fingers and toes really appreciate it!

Edit: I should also note that I am not hearing any noise from the dash that would indicate a problem with the actuator. Not sure if that makes a difference or not.
 
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mic98xlt

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City, State
West Haven, Ct.
Year, Model & Trim Level
98 XLT
03 Sport
Dee my wife has a 97 Ex which is basically the same system. She had the same problem with the appearance of the air conditioner blowing really cold air no matter which position the temperature knob was set. I sat down and read thru many a post here and on other forums about "Blend door" and "Actuator" problems. I was confused as all hell until I saw the You tube video "Heater Treater" I know it a promo for their blend door replacement but it showed me the inner working of the heater/ac box (Plenum) and just how the door is hinged and easy to get repaired once you gain their knowledge.
I really thought my wife's blend door was bad but I decided to check and make sure that the actuator which controls the blend door was good before I set out to repair the blend door. My actuator had the easy black tab type post that you can just easy unsnap it from the top of the heater assembly. I took the connector wires off the actuator and then unsnapped it off the heater. It has a long plastic shaft (about an inch) that goes down into the heater box (Plenum) which basically controls and physically turns the blend door to mix the heat (heater core) with cold air from the ac. The actuator pigtail connector is long enough for you to physically hold the actuator and then replug the connector back in. I then turned the car on and adjusted the ac/heater control knobs to see it the shaft on the actuator moved or made noise. I got absolutely nothing and the actuator acted dead. All of a sudden I noticed I was getting heat out of my dash air vents. Apparently my actuator was dead which then froze it in the cold ac position and thereby closed out the heater core portion of the heater box. Basically once I removed the actuator from the top of the heater box, it freed up the blend door to swing freely allowing the heat to flow thru. Looking back I also remember finding the right side of the heater box was hot but the left side was cold which told me the heater core inside was operating but not somehow allowing the heat to flow all the way thru the system.
Bottom line is that sometimes the blend door gets stuck because of a bad actuator which then locks out the heater core portion. I am using an Allen wrench to keep my blend door locked in an open position until I get a new actuator. My blend door did not need replacing and I could feel where the top of the blend door shaft mates with the actuator shaft was not cracked or broken. I think your blower motor staying on is something different from your heat problem and probably related to a bad blower (motor or resistors).
I think one of the best post on blend door and actuator repair is best summarized by the second link below. Common sense and baby steps first usually is the best solution. Good Luck!

http://heatertreater.net/Exp_Rngr Video.html

http://www.explorerforum.com/forums/showthread.php?p=2224644
 
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deek33

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2002 Explorer Sport 4x4
Thanks for the info. I'll tear in to it tonight. But, is it normal for the a/c compressor to run even when the heat is turned on? That seems strange to me.
 




mic98xlt

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03 Sport
I know it sounds crazy, but yes the air compressor does keep running majority of the time. This is without you calling for ac even in the plain heat control knob position. It's some crazy design by Ford which many have never noticed until they have an problem an incidentally see the compressor staying on constantly or cycling.
 




deek33

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OK - I found the actuator behind the glove box. I removed the actuator, left the harness plugged in, changed the temp control knob from hot to cold and the gears rotated fine.

Next I stuck a flathead screwdriver down in to the hole that moves the blend door. With the air turned to high I was able to turn the screwdriver and feel the blend door suction in to place. If I turned the air off I was able to move the blend door back to it's original position.

So it seems that the blend door and actuator are working correctly. What confuses me is that the plenum is warm to the right of the blend door, but cold on the other side.

Any ideas?
 
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deek33

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Looking back I also remember finding the right side of the heater box was hot but the left side was cold which told me the heater core inside was operating but not somehow allowing the heat to flow all the way thru the system.
That seems to be my problem. Does this require replacing the heater core? Or is there a way to properly clean it out? As I said earlier water seems to flow through just fine. Is it possible to flow in and out of the heater core without circulating through the whole thing?
 




mic98xlt

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03 Sport
It sounds just like what I experienced with my wife's heater plenum. The right side was hot or warm which meant the heater core was getting hot inside and water passing thru. The very top of the blend door has a sort of hollow shaft that is shaped to accept an "D" shape actuator shaft. The plastic shaft on the actuator is suppose to fit tight inside this hollow "D" shaft and moves the blend door. They are infamous for the hollow blend door shaft to break in half or become distorted making for the actuator to properly turn but not physically contact correctly or move the blend door inside the plenum. I would be sure that the top of the blend door shaft doesn't feel broken or distorted first. Feel with your finger the top of the blend door shaft and try to determine if it feels like the hollow shaft is complete. A regular screw driver blade didn't work for me and I had to use an "L" shaped Allen wrench into the blend door top shaft to hold the blend door open. It was the closest thing I could find which would physically fit in the short area above the plenum and go down into the hollow shaft. On my wife's heater I could feel and hear the blend door move with the Allen wrench. Without the Allen wrench, I heard the blend door physically being "suck" closed and no heat was coming out again only cold AC.

So in summary, please double check and use an proper size Allen wrench in the blend door shaft and recheck the blend door shaft is not distorted. Also make sure on the actuator itself the shaft is not somehow broken causing it not to mate properly with the shaft.

Sorry if I'm being long winded.
 




mic98xlt

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That seems to be my problem. Does this require replacing the heater core? Or is there a way to properly clean it out? As I said earlier water seems to flow through just fine. Is it possible to flow in and out of the heater core without circulating through the whole thing?
I think based on my experience with mines, you have fluid passing thru your heater core and it doesn't need changing. The heat is trapped inside (held hostage ;) )by the blend door problem. Meanwhile the ac isn't mixing with the heat causing an wicked cold vent output. I have attached an link to an quick fix for problems with the blend door shaft. It has several pictures that I think might also help you determine exactly where the problem is with your blend door.

http://www.blenddoorfix.netfirms.com/
 




deek33

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No need to apologize!... detail is good, and I appreciate your help.

I'm retiring for the night, but I'll try again tomorrow. I might cut the stupid box open so I can visually verify if the blend door is functioning.

It makes a perfect excuse for buying a Dremel tool, right?
 




mic98xlt

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Yes a dremel is a wonderful tool. I just brought one at walmart for $49.00 (300 model). Good nite.
 




deek33

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I think based on my experience with mines, you have fluid passing thru your heater core and it doesn't need changing. The heat is trapped inside (held hostage ;) )by the blend door problem. Meanwhile the ac isn't mixing with the heat causing an wicked cold vent output. I have attached an link to an quick fix for problems with the blend door shaft. It has several pictures that I think might also help you determine exactly where the problem is with your blend door.

http://www.blenddoorfix.netfirms.com/
I just verified that the blend door is opening and closing completely, just like it should be. I was able to stick my hand up in far enough to touch the heater core and it's ice cold.

So, since the line going in is hot, yet the heater core is cold, I wonder if it has some sort of bypass that allows the juice to flow even if there's a blockage. I'm not sure what else it could be at this point.

Edit: I just learned that there's a heater control valve on the line coming from the heater core. I'm going to bypass it or replace it (whichever is easier.. it's difficult to reach) and see what happens.
 
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mic98xlt

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98 XLT
03 Sport
On mines (97 Mountaineer) both the inlet and outlet hoses of the heater core were getting equally hot. You mentioned earlier that you were able to send water thru the core after you changed the fluid and thermostat. Was your fluid bad (rusty) and did you try to flush your heater core portion? Usually when the heater core goes bad it leaks and runs down out of the plenum plus you smell anti freeze inside the cabin first. I don't know of any bypass inside the heater core itself and it's basically an small radiator with an in and out hose connection. My wife's 97 had an vacuum controlled shutoff valve on the inlet hose but my 98 Explorer did not have one. If the heater core isn't working than it most likely would be some kind an blockage inside the core which you already have noted. I'm almost stumped and you have been thorough. I added a couple more links that might help. The first one is about flushing and locating the control valve on the inlet and the second is a basic diagram of an Explorer plenum showing how the air circulates thru the ventilation system.


http://forum.doityourself.com/archive/index.php/t-150249.html
http://autorepair.about.com/library/a/1g/bl958g.htm

I did a little more research and your should also have an heater inlet control valve. Follow the heater hoses back in the engine compartment and you should find a round black cylinder type with a smaller plastic vacuum tube attached. Perhaps yours is not properly allowing the fluid to flow thru to the heater core. Sometimes the plastic vacuum line leaks or the valve itself is bad. The vacum line is designed to draw the valve open and close to the inlet fluid flow into the heater core.
 
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deek33

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I did a little more research and your should also have an heater inlet control valve. Follow the heater hoses back in the engine compartment and you should find a round black cylinder type with a smaller plastic vacuum tube attached. Perhaps yours is not properly allowing the fluid to flow thru to the heater core. Sometimes the plastic vacuum line leaks or the valve itself is bad. The vacum line is designed to draw the valve open and close to the inlet fluid flow into the heater core.
I verified that the heater control valve is working as it should. I'll recap...
- Verified heater core is not clogged by running water directly through
- Inlet hose to the heater core is very hot
- Return hose from heater core is cold
- Replaced thermostat
- Verified blend door and actuator are working correctly
- Heater control valve opening and closing as it should

What are the two sensors under the intake? I think one is a coolant temperature sensor, any idea on the other?

The thing that baffles me is that the return line from the heater core is cold, so the flow has to be stopped by something. However, I know it's not in the heater core itself because I disconnected the return line from the firewall, started the engine, and witnessed the coolant spray out.

This sucks!:mad:
 




mic98xlt

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I'm not sure at this time what the sensors on the intake are exactly for. The only other thing I could suggest with extreme caution is to get a old external drop in type Ford heater core. I'm talking about the one's that just a mini radiator with exposed metal fins with inlet and return tubes on the end. You then could "jury rig" it up with the inlet and return heater hose in the engine compartment and feed the radiator fluid thru it to see if the external heater core does get hot. Such a undertaking like this is not for the faith of heart and reasonable care and caution would have to be taken to avoid getting physically burned by hot radiator fluid should a leak occur.

Are you 100 percent sure that you have reasonably made sure that the control valve is allowing the closing and opening to the fluid flow? Also that the core has been flushed forward and reversed out completely eliminating any possibility of an blockage or flow restriction? How about your thermostat, was it placed in the right direction? I'm not doubting what you have done or your ability, I just want to be sure that nothing is assumed. I'm really surprised with all your efforts, this hasn't been resolved.
 




deek33

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I'm going to take the alternator off to get a better look at the control valve. It's a possibility that the lever is broken and I just can't see it.
 




deek33

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I put a new heater control valve on and now my heat is working again!

Thanks for all of your help!
 




mic98xlt

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Thanks for the follow-up and and congratulations! It's been interesting to follow your progress. I always was confident you would find the problem and "heat" is definitely in fashion in the North already this season :)
 




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