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  1. #1

    How to test if an AC thermostat is working?

    Is there a trick to understanding if the AC thermostat is working properly?
    and - anyone replaced the thermostat on their AC (mine are 16K ocenbreeze with electric heat)
    Akin Tosyali
    Hatteras 41 -Barbaros

    Chicago

    Barbaros, Hatteras 41' Before and after restoration

  2. #2

    Re: How to test if an AC thermostat is working?

    I'll have a go answering this....

    The thermostat (whatever type will have three possible positions: heat, dormant and cool. If you had an old Cruisair three knob type you can hear the two clicks as you turn the thermostat knob between warmer and cooler. Also on the older type of thermostats, three knob or the silver Honeywell box type, the dormant stage is about 3 degrees. The thermostat itself takes its readings from either an older style copper bulb located at the air intake or possibly integral/attached to the digital control display. The Honeywell box allows you to set the temperature and cycles the compressor based on temperature (and not knob position.)

    On a cold day it may not be possible to make the aircon cool as the air temp is already below the lowest setting of the thermostat. The thermostat dormant position can also move about on the older rotary thermostats.

    What all this means is that the compressor will cycle ON (or OFF) when either the cooling or heating set temperatures are reached. Newer digital displays are more accurate. The older bulb thermostats can be adjusted to suit. So its a matter of seeing if the compressor and water pump clicks on and off depending on what cycle you are running.

    If you find the bulb you can put a warm or cold cloth on it to trick it into operating the compressor and water pump. Another way would be to put a digital thermometer in the airflow and watch the air flow temperature. It will either be heating or cooling when the compressor and water pump are running. If the compressor is OFF then the airflow will be returning to average room temperature. (The thermostat will also operate the Oceanbreeze system's heating element in the same way, but possibly the water pump does not run on the heating cycle.)

    According to my Cruisair guy, reverse cycle split system cooling airflow temperatures should be about 55F or 13C. Heating should be 96F or 36C. If outside these figures, then investigate possible water restriction, fan problem, dirty filter, clogged evaporator fins, or the unit needs to be regassed.
    Last edited by scottinsydney; 10-13-2019 at 04:12 AM.
    +++
    1984 61MY #353 with 9' cockpit extension.
    Sydney, Australia.

  3. #3

    Re: How to test if an AC thermostat is working?

    Nice post!
    Prometheus
    1978 53' MY Hull #529
    Viera, FL

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