Carrier 69NT40-511-199, 69NT40-521 manual Compressor Cycles OFF

STEP

A

B

C

D

E

Compressor Starting Sequence

Is Ambient

Temperature Less

Than 60 ˚F ?

YES

High Speed Start

Has Set Point Been Reached ?

NO

Continue In

High Speed

NO	Low Speed	Has Set Point
	Soft Start	Been Reached ?
	(See Note A & B)
		NO
		Run For 2
		Minutes

YES

Compressor Cycles OFF

YES

	NOTE A
During	compressor
operation, if at anytime the
High Pressure Switch (HPS)
trips, the logic will switch to
		3
Low Speed Soft Start.
		SECTION

NOTE B

Low Speed Soft Start is performed by closing the SMV to 0% opening for ten seconds during the start-up of the compressor. The SMV opening is then gradually increased to the desired value at the rate of a 3% opening per second.

Figure 3-7. Two-Speed Compressor Speed Change Logic -- Frozen Range Only

3-37 T-268-07