Heating and Air Conditioning: Tools and Equipment

JUMPER WIRE




The jumper wire is used for testing by short-circuiting switch terminals and to verify condition of ground connections.

CAUTION: Do not connect jumper wire between a power source and a body ground. This may cause burning or other damage to harnesses and electronic components.

VOLTMETER




The DC voltmeter is used for measurement of circuit voltage.

A voltmeter with a range of 15 V or more must be used. It is used by connecting positive (+) probe (red lead) to point where voltage is to be measured and connecting negative (-) probe (black lead) to a body ground.

OHMMETER




Ohmmeter is used to measure resistance between two points in a circuit, to check for continuity, and to diagnose short circuits

CAUTION: Never connect ohmmeter to any circuit to which voltage is applied. Doing so may burn or otherwise damage ohmmeter.

TEST LIGHT




The test light, as shown in figure, uses a 12 V bulb. Two leads should be connected to probes. Test light is used for simple voltage checks and to check for open circuits.

CAUTION: When checking control unit, never use a bulb over 3.4 W.