I have a 1988 Formula. Not heavily used, but things keep going slightly wrong. A bit like its owner, age is beginning to show!

Have just sorted a headlamp motor with the aid of lots of advice from the forum. Now the latest problem is with the heater/ventilation/aircon controls. I'm not sure whether it's an electrical or mechanical problem (and it's hard to see what happens in behind the dashboard/console).

Normally, as soon as the ignition is turned on there is a whirring and gentle "fwap" from behind the heater/vent/aircon unit, which I assume is the direction-vents positioning to channel air up, down or sideways according to the control setting. Similar noise when you press any of the buttons to change the airflow direction.

The electrics to the control panel still seem to be OK - since the fan-speed control and the fan itself still work. Pressing the aircon (B/L, normal or max) still fires up the A/C circuit. But.... the various buttons which direct the airflow to screen, dash-vents or footwells don't seem now to be having any effect. They aren't activating whatever there is deep inside the heater set-up to move the flaps which open and shut the various airways.

I have never tried to remove or examine the heater/aircon assembly of this or any other car. My Jeep controls the airflow direction by purely mechanical levers. On the Fiero, presumably the buttons activate some electrical circuit which drives motors, or servos, which then move or rotate levers and flaps inside the matrix.....

Aaaargh. Do the symptoms suggest an electrical problem (buttons not connecting to motor/servo/relay)? Or a mechanical problem (motors faulty - how many are there)? Or another physical problem (flaps wedged or levers jammed)? And whatever the problem, can it be solved without dismantling the entire fascia and console and taking out the heater/aircon assembly? As always, if anyone can tell me where to find an illustrated step-by-step troubleshooting guide, I'd appreciate it.

Do all the buttons do nothing to the flaps? (Defrost / Face / etc..) Reason I ask is that there are 2 separate motors, 1 of them only does the defrost flap. If both motors aren't making noise, it's not likely the motor, but something electrical leading up to the control unit. (fuse, etc..) Don't have access to a manual at the moment or I could tell you where to probe for voltage if you pull the HVAC control out of the dash.. It's not too complicated a system. If you stick your head down by the floor and look at the heater vents, you'll see the motors where they attach to the HVAC ductwork, there's white-ish plugs that unclip from them.. Might be worth giving a wiggle.

Thanks riceburner.... at least that encourages me to get upside down and take a look and wiggle wires. FWIW, it seems as if right now the blower-vents are stuck in the defrost (windscreen) setting as the air continues to blow out of the screen vents even when I hit the Htr (footwell) or Vent (dashboard slots) buttons.

But I do recall that last week, when I first suspected that there might be a problem, the air was blowing out of the dashboard vents and kept doing so even when I pressed the Htr or Defrost buttons. Figure that out! Intermittent problem? Bad earth?

Hmm.. It does sound as if it may be a bad connection somewhere, if both motors sometimes work and sometimes don't at the same time. I suppose it's possible that it could be the connector on the back of the heater controller, it's an "edge" connector that slides onto a solder-covered circuit board. It's usually a pretty tight connection, but 25+ years can do funny things to electrical connections. The fan speed knob is actually a completely separate high-current switch behind the faceplate, it's just attached to the same front panel as the other buttons.

**** Whoops, now that I think about things...... I was wrong in my first post - that 2nd motor is for the recirculate door, not the Defrost! Agh.. All the vents are controlled by 1 motor, the "recirculate" mode (which should come on when you hit AC Max) is the other motor... It normally is set to pull in fresh air from outside, but on AC Max it recycles the inside air to cool it off faster. So if you hear no motor noises when you switch AC modes back and forth, then that motor isn't working. If that one works but not the vents, then it could be the vent motor.. Hope that didn't confuse the situation too much!

Thanks again, riceburner... I did a little more looking around before seeing your latest post. That second-thought of yours about which motors/doors work which flaps makes more sense to me, but I haven't yet tested out what happens when I switch to AC Max.

It seems pretty clear that the vent flaps are currently stuck on blowing air upwards to the screen (ie the Defrost setting, far right button). The air still continues to blow only up through those screen vents when I press Vent or Htr, and also when I switch on the AC (at least to normal). That suggests the motor or door controlling the vent-direction ain't working. I'll have to check again using the AC Max button as to whether the other motor for the recirc flap is working.

One other thing I noticed tonight - and it may be a complete false trail - is that the illumination of the HVAC panel was extremely dim compared to the rest of the instruments and dials, even on max brightness. I'm embarrassed to say that I haven't driven the car much at night for a long time, so I can't remember whether that HVAC panel lighting was always very dim.

Going back to your advice about looking in the footwells and wiggling wires - driver's side or passenger's? Or since there are two motors/flaps, does that mean one visible each side (and if so which is the recirc and which the vent direction-control)?

If I remember right (keep forgetting to check when I'm home..) the recirculate motor is under the driver's / left side of the HVAC box, and the vent motor is more towards the middle. I'm not sure which side you can see that better from. The motors will look pretty much the same from the outside, they both have the same type of plug clipped on.

As for the HVAC panel lights, the voltage does go through the HVAC circuit board, but it doesn't connect to any HVAC functions. It has it's own ground wire and dimmed +12v wire going in. (though they may ground to the same point on the chassis, I'm not sure..) That could just be the bulb in there aging; if you end up removing the HVAC panel it would probably be a good time to get a new bulb for it. Those little tiny ones tend to get a black (almost black-chrome like) deposit on the inside after many years of use.

Here's a picture I took of the inside of the HVAC box (looking down) with the top removed.. Top left is the recirculate flap, bottom left is the defroster flap, bottom right is the foot/face flap. You can see some of the spring-loaded linkages that move the flaps at the bottom-middle, and where the blue+pink wires are sticking out under that is where the vent motor is attached. It's probably in the area right behind where the radio lives when installed in the car, maybe a little towards the driver's side..



And a top view... (the air box at the top of the picture is a Vintage Air GenII mini, this was a size comparison shot..) Again at the bottom-middle, you can see the vent motor a little more clearly. Thought I had some more pictures, but that's all I can find in my website storage..

That second pic is a help, riceburner... I saw some other pics/video of the HVAC unit out of the car, but had a problem figuring out how it was aligned and located when the thing is actually in place.

I have also narrowed down the problem. The recirc flap and control on my car's unit are fine. I tested by switching from Off to ACMax, and it is quite easy to hear it, and see the actuator moving, from the driver's side footwell (just above and right of the gas pedal).

It is the other motor or actuator that is playing up. I could to see and touch the white wiring connector from the passenger side footwell, and see the black plastic housing of the motor/actuator device. But the various spring-loaded levers that connect to the flaps are invisible and unreachable.

I thought the motor/actuator might just be stuck or jammed - so I gave it a few hard taps with a small wrench. Glory be, I was then able to switch the vent-direction from Defrost (Screen outlets) to Vent (dash outlets). I haven't yet dared to try switching it back again in case it sticks. But at least it proves that power is getting to the motor so probably not a wiring problem. Perhaps the flaps, or their hinges, or the springs/levers that move them, are just getting a bit stiff? The pesky thing is - if that is the case, how can one lube or free them up without dismantling the entire dash and taking the HVAC unit out and on to your living room floor?

LOL What's wrong with having it on the living room floor? It is a real pain to take that thing out, if I remember right the whole front "trunk" spare tire tub has to come out, among other things.. I got that one from a junk car before it was tossed, so it was pretty stripped at the time. I use it to test the aftermarket HVAC controllers that I make, I like to actually see with my eyes that it's controlling all the doors and blower like it should. I wish the thing were smaller, it's a beast to move around in my tiny, cramped "shop" room now.

Good to hear that the electrical seems OK, at least from the controller side of things. Inside the motor, there are metal (brass?) contacts that spin around on other contacts, making contact until they get to an empty spot where they stop. (so say you hit "face" mode, the controller gives power to the motor's "face" contact which makes the motor turn until it falls off the edge of that contact, and so the motor stops..) It's a very simple way of controlling motion without having to keep track of where the motor is. BUT, inside the motor with metal rubbing on metal isn't the cleanest environment in the world. There's a chance that the contacts in the motor are just dirty.. I would think if it was a mechanical "sticking" or binding of the doors that you would have heard the motor at least try to move a bit, and eventually move after trying several times. Where it moved after you tapped it, sounds more like a contact problem. I've heard that it is possible (though difficult!) to remove and replace the motor in the car, without taking out the air box. The trouble is the tiny bits that attach the rods to the motor, I think there's a little clip in there that has to come off / go on the end of the rod, inside the box. If you drop the clip inside the air box.... If it does turn out to be just a linkage lube problem, you might be able to get by with unscrewing the motor and pulling it out a little, enough to get a spray lube nozzle in to reach the linkages.. Never tried it, so no idea if it would work though.