Great Plains 1625AHL Operator Manual - Manual (Page 94)

90 1625AH Table of Contents Index Great Plains Manufacturing, Inc.
411-020M Table of Contents Index 2014-04-21
Magnehelic
®
Gauge Troubleshooting
If the Magnehelic
®
gauge does not read zero with the fan
off, inspect the gauge, and re-zero as needed.
Check for chamber and breather line problems before
re-zero. Re-zero cannot accurately compensate for leaks
and blockages.
Re-zero the Magnehelic
®
gauge on level ground with the
fan off, and if possible, under no-wind conditions. Turn
the set screw
on the meter face until it reads zero from
the tractor driver’s viewing position.
Problem Cause Solution
Non-zero
with fan off Zero drift Re-zero per
instructions below
Gauge
reading
lower than
sensor Relief port plug
missing/damaged Replace plug
Breather line
blocked or kinked Clear breather line
Leak in sensing
line Check line to
chamber
Gauge damaged Check for loose
cover, damaged
O-ring
1
Figure 97
Magnehelic
®
Gauge
29842
Port ID for Troubleshooting:
Over-pressure relief port (with plug in place)
Low-pressure port (breather/atmospheric pressure)
High-pressure port (from manifold chamber)
Alternate high/low ports are plugged.
Winter testing/maintenance advisory:
Gauge readings may be inaccurate or sluggish below
-7
°C (+20°F)
2
3
4
3
2
4
1