Ranchero -79, holes in the air ducts

Something is clearly missing from my air ducts, but what, empty holes?

 

I can't swear to it, but I believe they're supposed to be open, to dump some cool air at your feet.



Sorry it's a little blurry, but resizing reduced it from 3.4 to 3.3 MB I had to take a screenshot.

 

Andy is right on. If you lose vacuum, the system defaults to full defroster mode since visibility is more important than comfort. These openings allow some air flow at the floor level in any mode.

 

Yes you would also seem to have a hole there, at least on the right side, different from mine, or my duct is apparently cut.

 

Google Translate cannot translate this translation into my language so that I can understand it.

So those holes are in the duct that blows the air instrument panel.

Defroster mode = The air is blown on the windshield ?

If I lose the vacuum, then no air will flow from those holes in either direction ?

 

Make is correct, if it goes to defrost mode, no air will blow out of those. I believe they're supposed to allow a small amount of air to the feet in VENT and both A/C modes. When I get the blower motor replaced (hopefully soon), I can check that, see if I'm correct.

 

I don’t think those holes are meant to become air at all.
I think those holes are missing some parts of the Automatic Temperature Control system that I don’t have.

 

That is possible, but since I don't have a 1979 shop manual, I couldn't say. There is a spot in the dash on the passenger side for the ambient interior temp sensor, but that's the extent of the knowledge I have of '70s ATC.

 

I just hit on an idea--there are a few FB intermediate car pages, I can ask if someone either 1) has an ATC-equipped intermediate (T-bird and Cougar would be the most likely ones to have ATC), and therefore tell us if the holes are used by the ATC; or 2) ask if someone has a '77, '78 or '79 shop manual with the air conditioning section, therefore, be able to ID what those holes do.

 

Here are some screenshots from the 1979 shop manual. No mention or pictures of those holes. Maybe they're just there because they are...

ATC:


A/C:

 

I have the same holes in my 1978 full size Mercury Marquis Brougham with auto temp. Had another base Marquis with the same holes. All those holes do is allow a bit of heat to warm your feet when the defrost is on. That is the way they were built, leave them alone.

 

Really. Do you have a picture of it?
I haven't noticed that in myself.

 

Maybe I should be more distinct in my description. Nothing is missing on that a/c system. From your photo you have a fully manual controlled system with the temperature blend door controlled by a push/pull cable. The auto-temp version uses a servo vacume motor to move the temperature blend door instead of the cable. On those systems you still have to select what outlets you want the air to exit from and also select which blower speed you want. To me the late 70's auto-temp was a disappointment as Ford previously had true automatic climate controls capable of switching from heat on the floor to air conditioning from the dash registers along with regulating the blower speed as needed. Similar in actions to what is in a modern Lincoln Town Car. I still have a 1972 Mercury Marquis with that automatic climate control system and I love it. All Ford vehicles with factory a/c will default to full defrost blowing mostly on the windshield if they loose vacume from the engine.

 

If those holes are just in Ranchero's Automatic Temperature Control system ...
Or does Ranchero even have that system?

 

OK.
But in defrost mode, that door shown in the picture is closed, no air can flow through those holes ?

 

I have not seen a Ranchero equipped with the auto-temp system. That doesn't mean that they did not have that option. Those holes are in most Ford systems, manual or auto and serve the same purpose on all models. As I said, even the full size cars have them. The closed door in the drawing does not represent how tight it seals, air will leak around the perimeter seal on the door. Looks good on paper but in practice you will get some air flow. Just make sure both the partial and fully open vacume motors ( the horizontal ones to the left of the a/c - heat door ) move fully with vacume applied and release fully with no vacume. Check all the vacume motors and the other trap doors while you can observe them. If all the doors move freely and the motors hold vacume, it is as good as the system will ever get. If you had a heater core leak, wash out your ductwork with plain water to remove the coolant smell.

 

I'll get a photo of it shortly, since the dash pad is out. I have to access the fasteners for the blower motor case so I can get that done.

 

Good information.

So the only thing my car referred to as ATC was when I removed the old wires there was one yellow wire with white spots, it didn’t connect any components but was in reserve. That wire went close to the light switch in the engine room. ATC such a conductor could possibly have been between Electric vacuum relay> Water temperature sender / switch.

 

I have to make such a check as soon as I started the car sometimes.

 

You should check out the hand operated vacume pumps on the market today. Very handy for checking those motors and other vacume operated items. They stop you from having to run the engine to get a vacume source.