Specifications

PRIMARY CIRCUIT WITH FURNACE BLOWER OPERATING

If there is supply line voltage at the connections and no input voltage to the

power supply, the outage can be located by checking operation of the

safety switch and the interconnecting wiring with a multimeter. Refer to

Circuit Diagram, (Figure 9) to check operation of the switches.

Following these steps to test for proper operation of the circuit board and

power supply assembly:

1. Ensure that the circuit breaker controlling the furnace blower is in the ON

position and the main fuse is not open.

2. The power supply board has a built-in internal fuse to protect the 24V

transformer. It can be checked visually by inspecting the fuse. If the fine

wire inside the fuse is broken, this indicates a problem in the 24V circuit of

the power supply board. Do NOT replace this fuse. The entire power

supply board must be replaced. The purpose of the fuse is not to protect

the power supply board, but to function as a troubleshooting feature of

the product and to protect the transformer from damage.

3. If the fuse is NOT blown, check the ON/OFF switches and safety interlock

switch for proper engagement and operation. This can be completed

using a volt ohm millimeter on a scale that will measure ohms as low as

1.0. If you are using the recommended meter previously mentioned in

this manual, set the meter to read 200 ohm and proceed with Steps 4

through 6.

4. Remove the fuse. Connect one lead to the test pin located directly beside

the wire that connects the ON/OFF switch to the power supply board.

Connect the other lead to the fuse connection closest to the front panel.

5. Turn the ON/OFF switch to the ON position and depress the safety

interlock switch. The meter should have the capability of reading levels

as low as 1.0 ohm.

6. If there is no reading on the meter, begin the process of elimination by

disconnecting the wire from the test point and connecting it to the

terminal with the blue wire located on the safety interlock switch. Depress

the safety interlock switch. If the reading on the meter is greater than 1.0

ohm, the safety interlock switch is defective and must be replaced. If the

reading on the meter is less than 1.0 ohm, the ON/OFF switch is defective

and must be replaced.