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Discussion Starter · #1 ·
Thanks in advance for reading this long post.
I have searched several threads for the solution to "little or no cabin heat" in my ZX3. The inside of the car has little heat, not none, but I have to wear my coat everywhere I go. If I drive for 30 minutes or more, the temp warms up to acceptable levels, but the heater is still putting out lukewarm air. There is no change to how it has worked since I bought it Aug 2013 (so last winter and this winter).

This is what I have looked at, things that were identified in other posts: I took off the kicker plate below the steering wheel and verified that the blend door cable assembly moves full stroke (at least it appears that way from the 'nub' on the actuator going the full 3/4 turn both ways). I can hear the blend door go to the full 'cold' position when I move the temp control. I don't hear it noticeably going to the full 'hot' position, but I'm not for sure. The AC works fine in the summer, with the temp setting on 'cold'. The dash temperature gauge shows the car warming up like a normal car-- in the first mile or so, approximately center of the scale, the temp gauge stays rock solid at the normal temp position all the time while driving, after it has warmed up. I also flushed the heater core. I was really surprised that the coolant flowed freely thru the heater core, and the coolant looked very clear, not gunky at all. The coolant reservoir is filled to the normal range and the coolant looks very good there also. When I touch the heater hoses, they both appear to be at the same temperature (near but not over threshold of pain), but I'm not sure if I should be able to touch them with bare hands and not be in pain (?), I haven't made a practice of touching heater hoses so I'm not sure about the temperature on the outside of the hose. I couldn't get my hand to the main radiator hose by the thermostat to compare temperature.

So, I'm thinking 2 possibilities: 1) the thermostat, but why does the temperature gauge show it in the normal range and rock steady? or 2) the blend door really isn't moving all the way to the 'hot' position, but why can I hear it move and see the actuator from the outside seem to work? Possibly there is some generic defect with the actual blend door like on Ford Explorers?
Is there some kind of orifice going to the heater core that could be partially plugged?
The thermostat appears to be a pain to replace, or I would have done that in the beginning.
Thanks in advance for any ideas.
 

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2004 Focus Wagon, Zetec DOHC, Auto
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Thermostat and heater core sound okay from your description, so that leaves your #2 option.....the blend door.

When feeling the temp on the in/out heater hoses, was the cabin blower running?

If blower is running and temps are same on heater hoses, then no air is moving across the heater core. Therefore, blend door must be stuck in cool position.

That's what I am thinking anyway.......
 

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Discussion Starter · #3 ·
Thanks for the reply... I think you're probably right-- the blend door is probably the issue. Do you know any tricks for getting in and checking it without completely disassembling the dash? If the blend door is broken, will that require major disassembly? Thanks
 

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What are your ambient temps now? How long is your typical drive? How long does it take to warm up the engine?

I had problems with my 05 warming up in cold weather when it got down below 30F here. For one, there's a small air leak around the driver kick panel that allows air into the cabin. I definitely feel it around my feet. In 05, Ford supplied the new Focus Dtec engine with 180F thermostats, and that changed in 06+. Perhaps it was the new design. Anyway, our cabins just don't heat up. My thermostat was working just like yours doing it's job. The cabin just wasn't getting warm enough.

My solution is similar to what diesels do in extreme cold. I blocked off part of the radiator. I still do this once the winter weather gets low, but I have had it blocked off partially through the spring without any troubles. I unblock it before I need to start using the AC for something besides clearing fog from the windshield.

My first experiment was with cardboard and duct tape. When I say duct tape, I mean duct tape- not Duck brand tape or some other gray packing tape. I mean Nashau duct tape meant to seal up and attach AC ducting which can reach temps higher than the surface of my radiator. It's about $6 a roll at hardware stores. Remove the cover over the top of the radiator. 4 plastic screws and anchors, then slide up and off the grille. This exposes the front of the condenser. Size your cardboard up to fit into the slots. Completely cover it with duct tape, evenly so that it seals. This is to prevent the cardboard from dissolving in rain and getting into the radiator and condenser. That's why you have to make sure it is very well sealed.

At first I blocked off only one side. Then I blocked off both sides. You can check your engine temps in C using the electronic odometer trick. Check before and after. Key off, press and hold the trip reset button, turn key on, hold trip button until the odometer reads [test]. Release and the gauges start jumping and the odometer reads [gage], now each time you press and release the trip button you scroll through one of 30 test functions. Look for the one that reads [ 15 C] value assuming your ambient temp is 60F and the engine is cold. Start the engine, and drive. Now you should be able to watch your engine heat up to the point where the thermostat opens- about 80C- then cool off, and heat up again until it settles around 105C. In the winter, my engine never settled at a running temp above the thermostat setting on my 20 min ride to work. When the radiator was blocked off it would settle around 105C, with both sides blocked off it would settle within 7 mins of driving.

Try the same thing I did, first one side, then both sides. This increased my winter fuel economy too. Don't fear overheating because your condenser is blocked. Plenty of air flows through between the condenser and the radiator, and the condenser is not 100% blocked off on the front due to the bracket that supports the center of the opening. Now I use cut up semi mud flaps instead of the cardboard and duct tape which will eventually retain some moisture that makes the cardboard sag by the time I removed it. Just make sure you wrap it completely for the experiment, and you won't get anything in your condenser- I didn't. Also make sure you're using a quality duct tape that is designed to survive high temps and seal out water. Temps really don't get all that high on that side of the condenser, but the sealing and adhesive qualities of that tape are important.

Blend door problems result in temp variations between the two sides of the cabin. If the air flowing out of the passenger side vents is just as lukewarm as the air flowing from the driver's side- then the blend door is not your problem. Yes, that is not the function of the blend door, but when it isn't working right, that's how it acts. If you have good heat on the passenger side, but not the driver's side, then ok, it might be worth changing the blend door motor instead of my "that's so crazy that it just might work" solution.
 
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