KWE has developed a way of repairing the Delanaire Mark 2 aircon servo amplifier. Spares are unobtainable and the amplifier has a limited life. The symptoms of failure of this device are a lack of temperature and air direction control, even though the heating and cooling systems are working.
Similarly, KWE can now replace or repair the Delanaire Mark 3 frost thermostat, which is also unavailable new. This device commonly fails and forces the refrigeration compressor to run all the time. This in turn causes the compressor to fail prematurely and the evaporator matrix to freeze up (like a domestic fridge) and stop air from entering the car. Another symptom is the refrigerant pipes and hoses being covered in frost when the engine is running.