Heater controls

Here are some photos I took after replacing two of the four console-mounted slider controls in my '83 400i. This area was definitely the victim of a Dreaded Previous Owner (DPO). It is also an extremely unpleasant place to work in, because of the lack of access to the components and fasteners.

These controls consist of two air mixer levers and two coolant valve levers. Each mixer lever controls a flapper valve located in the kick panel, directly behind the round black plastic vent you can see there. The flapper has three positions. In the closed position -- with your control lever pushed all the way forward -- the flapper valve seals off the fresh air duct which originates under the front bumper (where a two-speed blower fan is also located), runs through the engine compartment atop the inner fender, goes through the heater core plenum, and terminates at this flapper valve area in the kick panel.

In the middle position, the flapper exposes both the vent in the kick panel, and another system of ducts leading to a dash vent and the defroster vents, to the air from the heater core plenum. (This is forced air -- very slightly forced -- when the blower fan is running). In the rear-most position, only the defroster and dash vent are exposed to the air from the heater core.

The other set of control levers in the console operate a set of valves mounted on the firewall, which regulate the flow of coolant to the heater cores on each side.

OK, so the problems with my car in its "as delivered" condition started with the fact that the DPO had installed a coolant valve lever in place of the mixer lever on the passenger side. The lever works the same, it's just the bezel that's wrong, being marked with a blue dot and a red dot rather than with the white symbols it's supposed to have. Also, the DPO had only used one screw to attach the bezel to the sheet metal component which both secures the control lever's plastic bezel to the console lid, and anchors the cable housing. The lack of this screw had allowed the sheet metal anchor to rotate when the lever was actuated, which massively cracked the end of the plastic bezel which did have a screw.

The coolant valve lever on the driver side was also cracked, for the same reason: only one screw was in place.

The other two levers were not cracked, and both of them had two screws, but all four of these screws were loose. Also, the DPO had swapped the cables on the coolant control valves, so that the driver side lever controlled the flow of coolant to the passenger's heater core, and vice versa.

Also, the flapper on the passenger side would not close all the way, so that hot air was always coming into the cabin. And the cables controlling the coolant valves are very stiff to operate. There's no denying this cable system was very down-market, even for 1983. l guess we can call it "character," but it's pretty bogus for an $80,000 car (about $200,000 in today's money).

Whatever. Here are my pictures. First picture shows the console instruments out and sitting on the dash, and my modern radio hanging from the rearview mirror. (My installer used butt connectors, soldered and shrink wrapped, so I didn't want to cut them.) The console lid is very easy to unscrew. First the two plastic-handled screws come out of the instrument bezel and you pull it out and set it on the dash. No need to disconnect the wiring. Then there are two screws hiding behind the instrument bezel, and two more under the ashtray -- which simply pulls out of its hole.

Next are three pictures of the underside of the levers. Like I said, it's a very unpleasant place to work. The masking tape is to protect the leather. The cylindrical thing to left in the second photo is a garden hose nozzle I used as a sort of miniature jack stand.

The final picture shows the "after." This job took about nine hours, stretched out over three days. I am happy not to have to look at those nasty cracked bezels anymore, and to have more or less full functionality from these controls.
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Hi Al. My wife and I and my boss and his fiance will be at the Sunday session of the Historics. We have attended many times. It's a good show, although very light on Ferraris. We should exchange pm's about meeting up.

I got my control levers from Eurospares. However they were unable to fill my order for two of the air mixer levers. Their stock must depend on the availability of wrecked 400i's. But Eurospares was much cheaper than the American sources I looked at.

The problem with working under the console lid is that the HVAC cables don't let you open it up very wide. That's the reason for my use of a garden hose nozzle as a prop. There is an option to detach all four cables from the anchors, but then you'd have to reassemble them, and then the limit on opening up the lid would be all the wiring to the console switches. If you're brave enough to unplug all those switches -- including the AC controls, which I did remove last Sunday (the knobs require a very tiny Allen key) -- well you're a better man than I.

But at least you can look at my photos and see the fasteners you'll need to deal with. Those dark brown phillips screws clamp the anchors to the plastic bezels, and they're very hard to get at. To remove my passenger side air mixer (the lower right lever), I cut it up with a soldering gun with a blade tip, because I could not get at the screw. I used hex head screws for reassembly. This allowed the use of a wrench, with which I could get at the fasteners from the side.

Detaching the cables from the anchors is comparatively easier than getting at the phillips screws at the bezels. To release the set screws which clamp the cables to the levers, I needed two tiny 7mm wrenches. In my case I was fortunate already to have on hand two sets of those Craftsman assortments of tiny wrenches which come in a small plastic snap pouch, and are sometimes called ignition wrenches. I used two because one would hold the female part in place while I used the other to loosen (or tighten) the male set screw. You can also use a socket on some of the 7mm fasteners. The clamps which retain the cable housings also use a 7mm wrench.

I learned that it's best to clamp the housing so that it protrudes just a little from the clamp and anchor part. (In my photos some of the housings are protruding too much. I adjusted them later, to protrude just a little.) Then I used the set screw to fix the cable at the length where the lever will go not quite all the way forward. This is the closed position for both the flow of coolant to the heater cores and the air from the fresh air ducts. In my opinion it's more important to be able to apply maximum force to shutting off the heat sources, than it is to have full travel all the way to rearmost lever positions. Now that I have full function of the air mixer flapper I have discovered that the fresh air ducts are marginal on a warm day and useless if you park the car with a hot engine and then hop back in a few minutes later. The ducts running through the engine compartment get so heat soaked that they offer only hot air, at least until the airflow has cooled them down. I doubt if it ever will, on a warm day. I suppose it's bad form to criticize Ferrari design, but this idea of running the fresh air system under the hood, rather than use cowl vents, is really dumb.