Sad Cow Horn Disease
On some Esprits, the horn stops functioning or sounds sick (like a sad cow). The horn in Esprits prior to 94MY is actually an air horn. It is made up of three basic parts: an air compressor and two trumpets as well as the tubing that interconnects them. The sad cow problem is usually related to the horn trumpets and is an easy fix.
The hard part is locating the parts. The compressor is located inside the
front-left wheel arch. To get to it, open the bonnet (hood), and locate the
windscreen washer fluid tank, it is aft of the left headlamp pod. Lift the
tank up and move it out of the way. The compressor is located behind the
tank's mounting bracket and is held in place with one bolt. It has an
electrical connector and 2 air connectors. One connector (the one that has
the 90 degree bend in it) is the air intake into the compressor. This one
should not have anything connected to it. The straight air connector has a
piece of that wonderful Lotus surgical tubing connecting it to the horns.
The tubing goes through the body in 2 very inaccessible places (I wouldn't want to try to replace it if I were you). If you have an Esprit SE or newer, it goes down in front of the left oil cooler (which has twin coolers). The panel where the horns are located is accessed underneath the front left corner of the vehicle. The horns are comprised of 2 diaphragms and 2 trumpets (D major and E major).
The tubing goes into a "T" that splits it so that it can feed both horns. I disconnected the horns from the "T" and hooked them up one at a time directly to the air compressor (i.e. the air pressure wasn't being split up between the two horns). They sounded sick, but even more interesting, with all this air pressure (2X), lots of junk started pouring out of the trumpets. The "junk" looked mostly like the white dusty oxidation that you get sometimes on certain metals as they corrode.
My next experiment was to connect each trumpet, individually to a bicycle foot pump. Doing this, I realized that it took an unusual amount of pressure to get a sound out of the trumpets. So I took 409 Glass and Surface cleaner (don't laugh) and I shot it down into each trumpet to clean them out. As the foot pump started pushing out all sorts of interesting bubbles from the trumpets (you can laugh now), I noticed that the pressure needed to make the horn sound got easier with each try.
My guess is that the road dirt, corrosion and other crud was keeping the diaphragms from doing their intended job. Anyway, once I cleaned both trumpets thoroughly, it barely took any pressure to make them work. I hooked them back up using the "T" and Voila! It was fixed.
Starting with the Esprit S4, Lotus replaced the air horns with standard GM units. This means there is no longer a separate air compressor. Unfortunately, this also mean that the classic European car horn sound is now gone. The horn now sounds like a higher-pitched Buick. Oh well, at least it won't sound like a sick cow any more.
By the way: Lotus likes to hide things into wheel arches. Examples of other things that Lotus hides in wheel arches are Barometric Air Pressure sensor in the right rear, and left and right manual fuel flap releases on either side. Four cylinder Esprits with the newer revised engine wiring harness also have the rear relay and fuse box relocated to the rear right hand side wheel arch.