Owner`s manual

Hydro-Hot Hydronic Heating System Shop Manual 07/03

Page 67

Section 8: Diesel-Burner Service, Maintenance, and Repair Information

Control Unit,

continue

NOTE: If after performing the following circuit tests, the Control Unit is

determined to be defective, and must be replaced, reference the Control

Unit's "Replacement Procedure" on the following page. Reference

Section

10 for spare parts information.

Ground circuit test

Locate the Control Unit's B-Plug and C-Plug, reference Figure 8. Insert the

probes of a DC voltmeter into the B-4 (+) and C-5 (-) locations and turn the

Diesel switch ON, reference Figures 4 and 8. If a voltage reading does not

present, proceed to the next circuit test.

VDC / VAC Control Thermostat circuit test

Locate the Control Unit's B-Plug and C-Plug, reference Figure 8. Insert the

probes of a DC voltmeter into the C-1 (+) and B-2 (-) locations and turn the

Diesel switch ON, reference Figures 4 and 8. If a voltage reading does not

present, proceed to the next circuit test.

VDC High-Limit Thermostat circuit test

Locate the Control Unit's B-Plug and C-Plug, reference Figure 8. Insert the

probes of a DC voltmeter into the C-4 (+) and B-2 (-) locations and turn the

Diesel switch ON, reference Figures 4 and 8. If a voltage reading does not

present, proceed to the next circuit test.

Motor circuit test

Locate the Control Unit's C-Plug, reference Figure 8. Use a jumper wire to

make a connection from the C-1 location to the C-7 location, reference

Figure 8. Turn the Diesel switch ON and insert the probes of a DC voltme-

ter into the C-2 (+) and C-5 (-) locations, reference Figures 4 and 8. If no

voltage reading registers on the voltmeter, the Control Unit must be re-

placed. If voltage is present, proceed to the next circuit test.

CAUTION: Be

sure to remove the jumper wire that was used to make

the connection from the C-1 location to the C-7 location. A failure to do

so will result in an overheating condition during normal operation.

Ignition Coil circuit test

Turn the Diesel switch OFF and locate the Control Unit's C-Plug, reference

Figures 4 and 8. Use a jumper wire to make a connection from the C-1

location to the C-7 location, reference Figure 8. Also, locate the VDC High-

Limit Thermostat and disconnect it's 2-way male plug from the (white

plastic) 6-way female connector, reference Figure 1. Insert the probes of a

voltmeter into the C-8 (+) and C-5 (-) locations and turn the Diesel

switch ON, reference Figures 4 and 8. If a voltage reading does not

Control Unit must be replaced.