HVH8 Pressure Transducer Troubleshooting

A low-pressure transducer is used on the HVH8 to interpret PSIG and is used by the control board (AOC) for compressor protection, loss of charge, and low pressure cut out. The information provided will allow you to determine if you have a bad transducer.

HVH8 Control Board

A pressure transducer is often called a pressure transmitter. It’s a device that converts pressure into an analog electrical signal. Although there are various types of pressure transducers, one of the most commonly used is a strain-gauge base transducer.

The conversion of pressure into an electrical signal is achieved by the physical deformation of the strain gages which are bonded into the diaphragm of the pressure transducer and wired into a Wheatstone bridge configuration. Pressure applied to the pressure transducer produces a deflection of the diaphragm which introduces strain to the gauge. The strain will produce an electrical resistance change proportional to the pressure.

A 5 VDC output low pressure transducer provides a 0-5 VDC data for the AOC control board to interpret for a 0-200 PSIG range of pressure at the suction line. This interpreted pressure data is then intelligently used by the AOC board for several safety functions: compressor protection, low pressure cut out, low of charge, EXV control, and lubrication management.

The suction transducer is a 3-wire plug PL19 on the control board. You will need a volt meter set to DC voltage to take a reading. As shown in the chart below, with a 125 psi reading on your gauges you should read 3 VDC between the red and black wire on PL19.