Back on track

You may wonder why I’m putting so much effort into the design of an air conditioning system when there is so much to be done to get the engine re-configured and running. Maybe I’ve asked myself that question too, but it has to be the right way to go. Based on the tales of stuffy, overheated Marcos interiors I know that I would hate driving in those conditions. I’m not a lover of excessive heat, anything over about 28 deg C I find uncomfortable. Also I want this Mantula to be a real GT car for long distances, not just short sprints.

Clearly that leaves me with three options, a conversion to soft-top, a Webasto type sunroof or a really powerful air conditioning system. I couldn’t go the soft top route because I just don’t want to lose the coupe body shape. Maybe the Webasto would be quite nice, but would it really keep me cool with all of that engine heat? That leaves the air conditioning as the way ahead.

The design of the a/c system has now been decided, a double blower will force the filtered incoming air through a large evaporator to be cooled and dried. The air then flows through the heater section where an adjustable gate directs the flow through the heater matrix or the bypass duct.  From there it cools or heats the cabin via electronically controlled valves.

SPAL blower
The SPAL blower is just the right dimensions for the air con box.
This Sirocco evaporator is rated at 9.6 kW
This Sirocco evaporator is rated at 9.6 kW!

The remainder of the system comprises the engine mounted compressor the condenser and the receiver/drier. All of these parts are to Ranger Rover spec or higher.

From my ¬†calculations the system should be more than capable of keeping the tiny Marcos cabin cool even on the warmest days. I’ll also use some Zircotec flexible ceramic heat shielding to prevent heat soak.

Just to make the whole thing even more complicated this will be a real climate control system with temperature, sunlight and humidity sensors. All vents, the compressor clutch and the blower motor will be controlled by an Arduino processor.

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