Bryant R-22 service manual CompressorPlug XIV. LOW-VOLTAGETERMINALS, Reciprocating Compressor

tion shown for the Tecumseh compressor is shown with the triangle formed by the terminals pointing toward the top. The configuration around the fusite terminals is the outline of the terminal covers used on the specific compressors. The slot through which the wires of the plug are routed is oriented on the bottom or slightly to the left or right. The correct plug can be connected easily to the compressor terminals and plug wires routed easily through the slot in the terminal cover. Therefore, if a Carlyle or Bristol compressor is substituted for a Tecumseh compressor, a new plug must be installed. If the plug is not changed, proper connection and routing of the plug wires through the terminal cover will be impossible.

CARLYLE		LEAD 3		BRISTOL
				COPELAND
		BLUE
C	S	C S		C	S
		R
	R			R
	LEAD 1			LEAD 2
	BLK.			YEL.
TECUMSEH
				LEAD 1
		C		BLK.
	C	S	R
S	R
	LEAD 3			LEAD 2
	BLUE			YEL.
TECUMSEH		LEAD 1
		BLK.		LEAD 3
	C			BLUE
	S	C
			S

RR

LEAD 2

YEL.

MILLENNIUM

LEAD 1

BLK.

C

C

R S

S

R

LEAD 3

BLUE

LEAD 2

YEL.

A94002

Fig. 27—Compressor Plug

XIV. LOW-VOLTAGE TERMINALS

The low-voltage terminal designations, along with descriptions and/or functions, are used on all split-system condensers and heat pumps:

—25—

G—Energizes blower circuit from indoor thermostat. E—Energizes emergency-heat relay.

W2—Energizes first-stage supplemental heat through defrost relay (wht).

L—Energizes light on thermostat with service alarm. W3—Energizes second- or third-stage supplemental heat. R—Energizes 24v power from transformer (red).

Y—Energizes contactor for first-stage cooling or first-stage heat- ing for heat pumps (yel).

O—Energizes reversing valve on heat pumps (orn). C—Common side of transformer (blk).

RECIPROCATING COMPRESSOR

The compressor is the heart of the refrigeration system. It pumps refrigerant through the system. If it malfunctions, system capacity and efficiency could be negatively affected.

CAUTION: The compressor is an electrical (as well as mechanical) device. Exercise extreme caution when working near compressors. Power should be shut off, if possible, for most troubleshooting techniques. Refriger- ants in system present other safety hazards. Always wear safety glasses and gloves when handling refrigerants.

Compressor failures are classified in 2 broad failure categories: mechanical and electrical. Both types are discussed below.

I. MECHANICAL FAILURES

A compressor is a mechanical pump driven by an electric motor contained in a welded or hermetic shell. In a mechanical failure, motor or electrical circuit appears normal, but compressor does not function normally.

CAUTION: Exercise extreme caution when reading compressor currents when high-voltage power is on. Correct any of the problems described below before installing and running a replacement compressor. Wear safety glasses and gloves when handling refrigerants.

LOCKED ROTOR

In this type of failure, compressor motor and all starting compo- nents are normal. When compressor attempts to start, it draws locked-rotor current and cycles off on the internal protection. Locked-rotor current is measured by applying a clamp-on ammeter around common (blk) lead of the compressor on a single-phase compressor, or any 1 of the leads on a 3-phase compressor. Current drawn when it attempts to start is then measured. LRA (locked- rotor amp) value is stamped on compressor nameplate.

If compressor draws locked-rotor amps and all other external sources of problems have been eliminated, compressor must be replaced. Because compressor is a sealed unit, it is impossible to determine exact mechanical failure. However, complete system should be checked for abnormalities such as incorrect refrigerant charge, restrictions, insufficient airflow across indoor or outdoor coil, and so forth, which could be contributing to the failure.

RUNS, DOES NOT PUMP

In this type of failure, compressor motor runs and turns compres- sor, but compressor does not pump the refrigerant. A clamp-on ammeter on common leg of a single-phase compressor, or any 1 lead of a 3-phase compressor, shows a very low current draw, much lower than RLA (rated load amps) value stamped on compressor nameplate. Because no refrigerant is being pumped, there is no return gas to cool compressor motor. It eventually overheats and shuts off on its internal protection.

RUNS, DOES NOT PUMP, HIGH-TO-LOW SIDE LEAK