Surna 1-18-01, Operating And Maintenance Manual

TROUBLESHOOTING

This unit is equipped with safety sensors that may include 
high and low pressure sensors for the refrigeration circuit 
and also a flow switch to help prevent freezing if there 
is a pump failure or other loss of flow. If any of these 
sensors detect a problem, they will not allow the chiller to 
function.

Some of the troubleshooting steps listed below can be 
performed by the end user, and some of these steps must 
be performed by a licensed HVAC technician. Retain this 
guide should your chiller ever require servicing.

TEMPERATURE CONTROLLER HAS 

NO POWER 

1. Ensure switch is in the on position.

2. Check breaker for proper function.

3. Check flow meter for adequate water flow (2.5  
    GPM per ton). Insufficient flow will cause loss of  
    power.

4. Visually check for any loose wires.

THE FOLLOWING STEPS SHOULD BE PERFORMED BY 
QUALIFIED SERVICE PERSONNEL ONLY

5. Check flow for proper voltage at the unit with an  
     electric volt-meter.

6. Remove the front cover of the temperature  
     sensor and check voltage.  If 24 VAC is presen  
     and all wires are installed and tight, the controller  
     may need to be replaced. If no  
     voltage is present, see step 7. 

7. The controller is wired so that it will not come on  
     if there is not sufficient water flow to the unit. If  

     there is no voltage at the controller, check the  
     flow and verify that the chiller is receiving at least  
     2.5 GPM for each ton of cooling required. If there  
     is sufficient flow, see step 8.

8. Check connections of the flow sensor (the flow  
     sensor is installed in the water line) to verify there  
     is 24VAC across the sensor while     
     sufficient water is flowing. If there is no voltage  
     across the sensor leads with a  proper flow-rate,  
     then the sensor needs to be replaced.

9. Check the direction of flow in the water circuit. If  
    water is flowing backwards, the flow switch will  
    not allow power to the temperature controller,  
    and the unit will not function properly.

TEMPERATURE CONTROLLER IS ON 

BUT CHILLER WILL NOT START 

1. The unit has a 5-minute delay on start-up  
    before beginning normal operation. Before  
    troubleshooting, ensure that 5 minutes have  
    passed.

2. Check the temperature set-points of the  
     controller to verify the desired settings are  
     still in place. The factory differential temperature  
     should be 3 degrees, and shouldn’t be changed.  
     For example, with the factory set differential  
     temperature setting of 3 degrees, and a desired  
     temperature setting of 45°F (8°C), the unit will  
     not start until the water reaches 48°F (9°C). 
3. Check to make sure the controller is set to C1.

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