As far as the climate control goes, an EV should not be any different from its ICE counterpart. Naturally, all the controls preferably should work the same way and used for the same purpose. You sure can wire it any way you wish, but having trunk open when A/C button is pressed or use speedometer movement to display the battery current, perhaps, is not a greatest idea. By the same talking when I design my heating system, I wanted to use components intended for the job. No, I'm a clever engineer too, and like to recycle components by using them for not intended and sometimes unexpected purpose. A hair dryer as the cabin heater, or an audio amp fed with sine wave as small AC inverters are quite common; how about graphite pencils as resistors, and fish line as fiber optic elements? However, after years of practical experience with all that, I can tell you that if a decent company designs a product specifically for your application, unlikely you can beat reliability and convenience of using just that. Even if it cost more initially, I learned to value my time more than a while ago when I was willing to fix any hobby quality gadget just because I can and it's cheap. The heater is the perfect example.
My goal was to have the cabin heated just like stock system would, make it reliable and safe, easy to install and control and preferably not to tear the dash apart for installation and maintenance. So, what would be the best solution for heating an EV? Surprise: an EV heater! Many people use a fan blowing through a ceramic heating elements, but that solution did not appeal to me because a) exposed hot nichrome wire, even out of direct reach, is not my idea of safe equipment, and b) required to modify existing heater core under crowded CRX dash. Perhaps, I'd use that if no other option would be available, but there was: a Swiss made RM-4 EV heater made by DES-MEA. This unit is rated at 2 kW, works with 200VDC...450VDC input voltage range, and consists of the water tank (miniature version of a home electric water heater) with heating element, water pump and PIC processor based contactless controller integrated in it. Controller takes care of maintaining preset temperature of 90'C regardless of the input voltage swings typical for an EV, as well as self-testing, interlocking and performing necessary safety checks. Application is very easy - all you have to do is plumb inlet and outlet to the existing heater core, connect the power wires directly across the propulsion pack, a switch to supplied control harness and pour the water in it. That's it. The heater functions identical to ICE system - hot water circulating through existing heater core, and you retain all the control for fan speed i.e. amount of heat in the cabin.
The RM-4 EV heater as comes from the factory - side view.
Heater rating label
Auxiliary water pump rating label
The aluminum bracket...
...mounted on the fire wall near the heater core fittings.
Installed and plumbed heater.
Installed and plumbed heater - side view.
This is it.
The Air conditioning
The air conditioning is not implemented yet, but all necessary components are retained. Stock CRX A/C radiator (still in the car) and stock A/C compressor will be used. On this photo my previous implementation is shown. It worked fine, compressor was driven by Leeson 1.5 hp 180VDC 6.7A PM DC motor via spider type coupling. In my current project intention is to use small 3 phase AC motor rated at about 380 VAC and fixed frequency 3 phase solid state inverter. The shaft of the compressor will be modified (shortened) and the motor-compressor combo physically will be one compact unit. No longer high priority part (I live up North now), so may not be implemented this year. But eventually it will.
Old conversion installation - PMDC motor linked to
the stock A/C compressor
Old conversion installation - under hood view. PMDC motor takes quite a bit of space.