Danfoss Fault Location Installation guide

C O M P R E S S O R S

Technical information

Fault Location on

PL, TL, NL, FR Compressors

R E F R I G E R A T I O N A N D A I R C O N D I T I O N I N G

General	This Hermetic Note is directed especially to the service network, for house-
	hold appliances and similar. For detailed information on compressors see the
	data sheets.
	Compressors type PL, TL, NL, FR and partly SC are equipped with a PTC
	starting device (fig. 1) or a relay and start capacitor (fig. 2). The motor protector
	is built into the windings.
	In the event of a start failure, with a cold compressor, up to 15 minutes can
	elapse before the protector cuts out the compressor.
	When the protector cuts out and the compressor is warm, it can take up to 1
	hour before the protector cuts in the compressor again.
	The compressor must not be started without the electrical equipment.

	Fig. 1: PTC starting device	Fig. 2: Starting relay
Fault location	Before beginning systematic fault location, a good rule is to cut the supply
	voltage for at least 5 minutes. This ensures that the PTC starting device has
	cooled off and is ready for start.
	A voltage drop or blackout within the first minutes of a pull down of the
	appliance with cold compressor, can lead to an interlocking situation. A
	compressor with PTC can not start at non equalized pressure and the PTC
	does not cool down so fast. It can take more than 1 hour until the appliance
	then operates normally again.
Electrical compressor	To avoid unneccessary protector operation and consequent waiting time, it is
quick check	important to carry out fault location in the sequence given below. Tests are
	made according to desriptions on following page.

• Remove electrical equipment

• Check electrical connection between main and start pins of compressor terminal

• Check electrical connection between main and common pins of compressor terminal

• Replace compressor, if above connection checks failed

• Else, replace electrical equipment

If the compressor still does not operate, most probably it is no electrical compressor failure. For more detailed fault location, see the tables.