1989 Tempo GLS - Panel Vents/Vacuum Lines/HVAC Switch

I have a 1989 tempo that suddenly decided to no longer allow air to come out of the panel vents. I did some troubleshooting, looked up as much info I could online and in Chilton's, and I'm currently almost to
the point of completely taking the dash off. I'm hoping someone else with experience can help stop me from spending a whole day attempting that.
Basically, air will only come out of the Defrost and Floor.
-- If I choose AC/MAX AC/Panel Vents air will come out of the Window Defrost vent.
-- If I choose Defrost it will come out of the Window Deforst Vent. -- If I choose Floor it will come out of the Floor vents.
This happens for both heat and cold.
I have come to the conclusion that it is either a vacuum problem or somehow related to the vacuum lines.
Behind my glove compartment are 2 vacuum lines, one black and one white. They are both fastened tightly and do not appear to be leaking. I have not disconnected one yet as I am unsure of if that will cause any other problems. Is it safe to remove one of them from the connector while the car is running?
If there are only two lines, would the Window/Floor switching seem to indicate that these lines are fine, or could one of them be the culprit?
Also, has anyone ever pulled out the heating/ac control unit from the panel? I have the tools to remove my radio, and the unit has the same holes. I can pry it out a little with those tools, but I get enough resistance to be afraid to try to pull it out any farther. Does the switch (between various degrees of hot/cold) need to come out first, or is there anything I'll break by pulling this out?
I just want some reassurance that I've tried everything I can before taking apart the whole dash. Any tips would be appreciated, including on if it's safe to disconnect one of the 2 vacuum lines behind my glove compartment while the car is running. I figure I could use my finger simply to check if any exchange is taking place.
Thanks
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I'm not familiar with your model, but I recently had a HVAC problem, in my '98 Ford Club Wagon. I did NOT have to disassemble the whole dash. I did have to do a lot of disassembly of the right part of the HVAC system, however. Without studying your account in detail, I would encourage you to localize your problem. Perhaps you have a bad vacuum motor. An experienced HVAC person might come along here, if you are real lucky, and tell you where to look. Absent that, you'll have to deduce the specific problem the old fashioned way, scratching off some skin from your knuckles along the way. Yeah, it's OK to temporarily open vacuum lines with a car running. However, I would caution you against leaving your body in the way of a dashboard airbag. It could ruin your whole day, if you get punched out that way. You can buy a vacuum test kit, which has a "pistol-with-vac-gauge." You can INDUCE vacuum with the pistol, by repeately squeezing. That way, you can test vacuum motors. Look for a bound flap, too. Maybe the actuator is OK, but it just can't budge a flap that has lost its smooth operation over the years. Good luck. PS The blender door in my car was actuated with an electrical position motor, not a vacuum-acutated motor. All other HVAC position motors were vacuum-actuated.

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Thanks. I'm thinking it could be the flaps, or a vacuum leak much farther up. You mentioned a vacuum test kit. I noticed that AutoZone loans one out for Valvetrain repair. I'm afraid my knowledge of things that indepth is severely lacking, but would this be along the lines of what I need? http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/in_our_stores/loan_a_tool/valvetrain_repair/vacuum_pump.jsp
Or would I want to break down and buy a specific one?
Thanks

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Yeah, that's what you want. Hey, vacuum is vacuum. You don't need to get any specific model. And if that dashboard airbag deploys, remember to "duck"! Either think ahead...or think FAST. ...! On my car, the means to inactivate the airbag was to disconnect the car battery, and wait 5 minutes. Check you service manual for similar instructions. The idea is that, if you're in a crash and the electricity "goes out" in those critical milliseconds when the airbag must deploy, the airbag system must have its own reserve of electrical energy to permit the bag to deploy.
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Jerry wrote:

on my taurus. As the motor reved up, the air would go from the middle vents to the defrost! That drove me nuts.
One of my vacuum motors was leaking. I had a handheld vacuum pump with gauge on it. I pulled the hose on each vacuum motor and put the pump on it. I then pumped it up and saw if the vacuum motor moved. MOvement is good. Then, i waited to see if it leaked down. If the motor is bad, it will leak down to no vacuum quickly.
Bob
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Thanks. I'll give it a try. Fortunately (or unfortunately, depending on the case) my car doesn't have airbags so I don't need to worry about them deploying.
If it was a vacuum motor, do you know approximately where they're located at? I have diagrams, but they don't really show it in relation to anything else.
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