MUA-SVX01A-EN • Direct-Fired Make-up Air
81
Trouble Shooting
Note: The Direct Fired Control (DFC) from RTC Solutions™ provides diagnostics
via the on-board LED labeled POWER/STATUS. A system fault is indicated
by a fast blinking LED (2x per second). This usually indicates that the
sensor or dial are either disconnected or improperly wired. Check all
connections per the wiring diagrams. The fault also may be caused by a
damaged sensor or dial. Both devices may be tested with an Ohmmeter
by removing the wires from the direct fired control and measuring across
the devise. The device should measure between 12.8 K and 7K ohms. If
there is a fault light and the device measures the proper resistance, the
control may be damaged. If no fault light shows, but the system is not
modulating properly, check the control output by repeating the start-up
procedure and measuring the voltage across terminals 5 and 6 on the
direct fired controller as follows: Remove the wire from terminal number 4
Photohelic or null switch not
installed correctly.
a. Check wiring.
Temperature control
defective.
a. Install correctly (see
manufacturers cut sheets).
Temperature control wired
incorrectly.
a. Check and/or replace.
Temperature control bulb
installed incorrectly.
a. Check wiring.
2-position switch defective.
a. Install bulb in correct
location.
Damper motor and/or
potentiometer defective.
a. Check and/or replace.
Dampers binding and/or
loose.
a. Check and/or replace.
10. Burner will not turn on in
low speed.
Low air flow switch open.
a. Check and/or repair.
Profile damper not closing (if
applicable).
a. Check to ensure velocity is
correct.
a. Check and/or replace.
11. Flame length too long in
Incorrect setting or defective
MP-05 in electrical panel.
low speed.
Low speed high fire set
incorrectly.
a. Check setting or replace.
a. Make normal maximum and
minimum fire adjustments as
outline earlier. Open switch RE-
52 and remove wire from
terminal #4 on MDT system or
terminals #2 and #4 on MRT
system. Adjust MP-05 (located
in electrical panel) for
approximately one half of the
firing rate. Reconnect wiring to
amplifier.
Table 16. Trouble shooting guide for systems with pilot (continued)
Symptom
Probable Cause
Solution
