Cruisair Heat stopped working

I am going to dig into this more fully over the weekend including model numbers but for now, here is the dilemma.

My salon AC (three knob) works great in cooling mode. It is wired so that the water pump turns on and off with the compressor. When in cooling mode, both the water pump and compressor work fine. When running in heat mode over the weekend however, the unit suddenly stopped. On investigation I found the compressor humming and the water pump not on. I thought I fried the compressor but when I switched back to cooling, everything works great.

The question now is, what would cause the water pump and compressor to not run, only in heat mode. I'd say reversing valve but that would not affect the electric water pump, so it must be an extreme low voltage issue to both the pump and compressor?

Any ideas on where to look or test with the minimal information I have so far?

I have just serviced my 7 air cons some with the older 3 knob controls. My galley aircon exhibited similar issues in that it would neither heat nor cool nor turn on the pump.

Luckily my business sells Cruisair products so I had access to the local Australian technician. I ran through the symptoms. In the end he asked was it a cold or hot day in Sydney? He also asked if the thermostat bulb in front of the air intake was clean. It looked that it had 35 years of dust on it. And a moment later it looked brand new again and the rag was put in the rubbish bin.

Turns out that the position of the thermostat clicks on the dial changes with temperature. Sometimes it clicks at 5pm and sometimes at 11am. The tech asked me to wrap the bulb in a hot towel. This immediately started the compressor cooling. You could do the reverse and wrap the bulb in a cold towel. This should change the thermostat click position and the unit should heat. It may also be the reversing valve is stuck or the terminals to it are dirty.

Also the in a normally wired setup, the compressor and water pump trigger should fire at the same time.You may also have dirty heat exchanger coils that need cleaning. Cleaning the coils reduced my output air flow temp from 16 to 13 degrees C on all units.

I also checked the Galley compressor wiring box and found a badly degraded wire connection to one of the capacitors that connected to the compressor.

Hope this helps.

There are many different schemes for voltage routing and control for these Cruisair units and I don’t know your exact set up. That said, since you have a three knob control it is likely that line voltage goes to the three knob unit and line voltage is then routed from the control unit to the compressor and water pump or the water pump relay if that water pump is shared with another Cruisair unit. In this set up any water pump relay is line voltage controlled as apposed to low voltage controlled. In other units all signal control is low voltage and so line voltage is switched elsewhere for the compressor and the water pump and the control head has no line voltage input or output. Clearly you have a line voltage problem in heat mode and since it affects both the compressor and water pump I suspect that line voltage runs directly through your three knob unit and is corrupt on its way out in heat mode only. I would suggest measuring line voltage at the compressor and water pump first in cooling mode and then in heat mode. Then check the back of the three knob control in both and see if the findings agree. If they do then your control unit is bad. If you give me the exact part numbers of everything We can skip some of the guessing.

George