ICM Controls ICM326H Application Manual

Contents

ICM Controls ICM326H Application Manual Manual pdf 11 page image

9SYMPTOM REMEDYUnit fails tostart The sensor may not be connected or it is defective.With the probe disconnected, use an ohmmeter to measurethe resistance between the probe wires. It should match thechart in Appendix B. If you read an OPEN or SHORT, replace thesensor.Fuse and/orcircuit blows The unit has been mis-wired and may be permanentlydamaged.The fan cyclesfrom full ON tofull OFF withlittle or nomodulationFirst turn OFF the power. Reapply power and confirm hardstart operation. Reduce the hard start period to the minimumsetting required to accelerate the fan. Excessive hard startingcauses large pressure drops by moving too much cold air overthe condenser.Check position of heat pump select jumper (see Pages 6-7).Should the cycling persist, move the probe up several bendsinto the condenser to increase the sensitivity to condensingtemperature.Fine tune cutout adjustment.The fan doesnot come onat allMeasure the line voltage between LINE 1 and LINE 2 to confirmthat the line voltage is present.Remove the thermistor probe from the terminal block andmeasure its resistance at ambient temperature. Compare yourreading at the appropriate temperature in Appendix B to seeif the actual resistance approximates the listed value. Next,hold the probe in your hand and confirm that the resistancedecreases.Place a temporary jumper across the S2 or S3 terminals. Fanshould run at full speed. If it does, recheck probe connectionand verify probe is operating correctly.The highpressure switchtrips offMove the probe farther into the condenser where thetemperature is higher. This will produce a higher fan RPM anddecrease the head pressure.Fine adjust the cutout and hard start settings.Troubleshooting