348 HVAC fix!

Hi everyone!! recently added a 1995 348 GTS in red and tan to my collection... still have my 1978 308 GTS (silver and black) ...love the cars!!!
now onto a problem apparently well known to 348 owners... the Veglia Borletti HVAC unit which cannot be bought new for any price, and which is, shall we say.... underengineered.... in my particular unit most buttons were not working at all , the button labels have fading and worn surfaces plus the unit had a cracked and dull green plastic display window. Not up to par with the rest of the car.... I believe I have located a rebuilt unit in Europe and have sent payment, so I have accepted the risk of further damaging my old HVAC and have taken it apart and studied it... retrofitted a repair/improvement ...and I fixed it!!

I dont know about other units but here are my observations on mine... the design of the way the pushbuttons actuate the switches on the circuit board is flawed.... there is NO moving actuator or linkage from the button you push down to the switch on the circuit board. The system physically has the exterior case with moulded-in black plastic cylinders for each button you push, and relies on the DEFORMATION of the case locally as you press a button to allow these cylinders to make contact with the switches. Now plastic is..well...plastic! and my case is actually warped a little. Enough so that pressing those buttons still wont allow the rigid cylinders to contact the switches.

what was needed was a separate "slightly" movable "floating" actuator to touch each switch on the circuit board.
so here are the steps for my solution

1) CAREFULLY and completely disassemble your HVAC unit, removing the circuit boards and the inner black plastic flat piece that the boards screw on to.
carefully peel the individual button labels off the buttons by wedging a razor under a corner and pulling up. make note of the label positions on the unit by taking a photo or drawing a diagram and save the buttons. I found a company that can duplicate these button labels for around $30.00 (maybe they can offer these as a kit!) so I will be changing mine out.
push the clear plastic parts backward out the inside space of each button. In my fix they are not reused. Remove the green clear plastic display window.

2) Hold the front case and Using a Dremel drill, Carefully drill away completely the rigid moulded-in black plastic cylinders found within the footprint of each button space ... they are in the upper right corner within each button space. BE CAREFUL NOT TO DRILL AWAY BEYOND THE FOOTPRINT OF EACH BUTTON!

3) replace the circuit board and you should be able to see the small round white switches of the circuit board clearly and fully under the sites of the buttons.

4) Now refasten the black plastic inner plate to the case and refasten the circuit boards.

5) Now comes the tricky part... you will need to fabricate 13 "actuators"...one for each push button. I experimented with various materials and of all things I found that a larger size new paperclip (!!) has the needed strength with flexability plus the ability to be bent into the needed shape.
the design I came up with is an upside down "U" with the elbow made flat/straight. the arms go into the button space once occupied by those clear pieces ... one arm rests on the round white button of the switch on the circuit panel. the other arm rests on small ledges created by the black plastic flat piece screwed to the case...
*** there are a few button spaces that dont have these ledges and so the corresponding arm is made longer and rests on the circuit board (put something thin between the board and the arm tip to protect the circuit board)...
the "actuator" fits diagonally bridging the button space. the flattened elbow of the"U" faces up/out diagonally and sits just below the sideways profile of the button so if you turn the case sideways and look there should be no metal protruding beyond the level of the button decals .... the button decal thus sits right on top as before, supported by the flattened diagonal elbow just under it . I measured each site individually for depth to the switch, depth to the ledge (or to the circuit board for those sites with no ledge) and length across the diagonal of the button space. the resulting piece should fit loosely in each hole and not protrude as above, and the arm on the switch button should not be able to slip off it. I continued the length of this arm by bending it upward to form a rounded surface that rests on the switch and wont damage it ...I continued it upward then bent it downward to create a 3 dimensional approximation of the cylinder that was drilled out. I will need to include photos obviously.

6) once all 13 actuators are fabricated and in place, one by one remove and apply a tiny bit of Krazy glue (yes there is a difference in glues and Krazy glue is best) to the tip and shaft of each arm that will be resting on the ledges, and put each actuator back in place. be sure NOT to mix up which actuator goes in which hole as each will be a little different!! be sure each arm rests on each switch... you should now be able to push on each activator and feel/hear a click as it depresses the corresponding switch.

7) using a little bit of Krazy glue at each button site on the case, reglue each button label to the correct spot.

8) cut out a correct sized piece of amber red clear plastic and Krazy glue it to the window display sites on the case.

9)work Stabilant 22 into the electrical connectors and reassemble the unit.

10) plug it in the car and PRESTO!! you should have a unit where each pushing of a button results in a click and working functional controls (assuming your electonics are ok)

 

one point I failed to go over was the order and means in which I bent the metal to fabricate the actuators...
a) take a larger good quality new paperclip (still cant believe such a rigged-up sounding method works!) and bend the 2 ends out 90 degrees so the tips point away from one another.

b) using hemostats (needle nose pliers should also work but they cant lock like hemostats) squeeze the remaining "u" of the paperclip close to the end of it until the 2 lengths touch ...the resulting shape of the "u" should be narrow but rounded off... and this now is the rounded tip that will be resting on the switch of the circuit board.

c) stick this tip into the button space until it lightly rests on the top of the switch... then take the hemostat and rest it across the opening of the button space and clamp the jaws on one of the arms of the paperclip protruding out of the hole... this is the measurement at which you will need to bend the paperclip in order to form the flattened "U". back the hemostat downward a TINY amount towards the rounded tip, reclamp, and bend it a relatively tight 90 degrees.

d)bridge this straightened part diagonally across the hole space, right upper to left lower, and reclamp the hemostats on the paperclip at the point you will want to bend it to complete the upside down "U"... the resulting piece should fit a tiny bit loosely in the hole space when you stick it in with the "U" rightside up.

e) with the paperclip in this position with the arms sticking out, clamp the hemostat across the arm you just formed, with the hemostat again resting across the surface of the hole space.... then remove the clamped paperclip and back it upward a TINY bit. this will be the spot you will cut this arm -to size- so it rests on the ledge.

f)on the opposite arm, with the rounded tip, bend the extending part of the arm in a tight 180 degree turn back downward and cut off the resulting parallel arm just above the rounded tip.

g) hold the now-formed part as an inverted "U" with the flattened elbow horizontal to the ground and the arms pointing down...clamp one hemostat down the length of the horizontal flattened elbow, and then clamp a second hemostat across the bend of the arm with the rounded tip... you will need to bend this arm leftward so the curved tip and extra arm now form a little leftward "L" sideways but still points downward parallel to the thinner arm

h) you are now done, though you may need to bend and tweak for it to fit right.

i) on the button spaces without a ledge (3 of them) you will need to measure the depth of each directly and cut the thin arm length based on this depth

g)

 

been away on vacation a bit and in the meanwhile my new hvac unit arrived ... it is actually a NOS unit not rebuilt!! I feel very lucky to have what must be one of the last ones on the planet... going to keep it carefully packed away for the future . Also my decals for the buttons on my original hvac unit arrived!! graphics are sharp and accurate !! many thanks to Robbie for a beautiful set of decals. Will post photos of my project soon ... need a new camara. All 348 owners with faded hvac buttons now have

 

an inexpensive solution to this cosmetic problem. you should contact 285ferrari and get a set!