Ford Repair: Ford Taurus heater problem, coolant level, ford taurus

Question
Hi Tim:

Thanks for answering.  My car's blower is still working--it puts out a normal amount of air, but cold.  The temperature of the blower's air doesn't change no matter what position on the dashboard's temperature dial I set it to.  When I turn the temperature dial, I can hear the blend door's motor humming appropriately, so it seems to be OK, though I can't vouch for the blend door itself since I can't see it without removing the dashboard, which I'd rather not do unless necessary.  The temperature gauge is something I'm not sure about--a few days ago, I noticed the gauge was just starting to go into the red, something I hadn't seen it do before--normally it's either in the middle or a little towards the red.  I pulled over and checked the coolant, and it was low (I don't know how low, since I couldn't see any in the bottom of the coolant reservoir), so I added some (50-50 antifreeze and water).  The temp gauge then went down to between midway and red, and stayed there.  However, there was still no heat from the blower, so that's why I mentioned in my question that the coolant level was normal, though maybe the overheating and low coolant prior to my adding some has something to do with the problem?  I'll check the thermostat, but right now I don't know how to do that.  Thanks again for your help.

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The text above is a follow-up to ...

-----Question-----
I used a car wash's high pressure water hose to clean my 1994 Taurus's
engine and the surrounding parts, and right after that, the heater stopped
working most of the time.  Sometimes it puts out a little heat for about a
minute out of every 10 minutes or so, but it's not consistent.  Could I have
knocked a hose loose somewhere, or gotten water somewhere it shouldn't
have gotten?  I've been given the lecture by my brother that I did a dumb
thing, though I already knew that.  I've seen mention of backflushing the
heater core to clear out any junk that might be in it--how do I do that?  Also,
the coolant level is good, so that's not the problem.
-----Answer-----
John,

When you say the heater is not working, due you mean the blower motor is not moving air or that the blower runs fine and the air coming out is cold?

I can not think of any reason for a pressure washer to have damaged your heater. I would check that your engines thermostat is not opening early and not letting the car warm up fully. Does your temp gage stay in the middle like it should?

Let me know and I will try to better answer your questions.

Answer
John,

I hope you had a good Christmas. sorry to reply late, but took a breather for the holidays.

On your Taurus it is very possible there is an air pocket trapped in the cooling system causing your heater not to blow hot air.  To check it, begin with a cool engine. Remove the radiator cap and top off the coolant. Now start the engine and let it run until it fully warms up. Keep an eye on the coolant level, as air bubbles "burp" out it will lower so keep it topped off.  Once your upper radiator hose is good and hot the thermostat is open. Reach back behind the engine and feel your heater hoses going into the firewall. They should both be hot. If they are and still no heat, then your blend air door is broken inside the A/C box.  If the hoses are still not hot check to see if it has a heater control valve stuck off. I don't believe Taurus uses one though.  

Also, if the system is low on coolant have a garage pressure test the cooling system as there is a leak somewhere causing the problem.

Let me know how it goes.