Problem
Unit goes into a supply fan proving fault but the VFD never tries to start. This fix applies to units without the Supply Fan VFD Bypass option or with Supply Fan Bypass option but the unit is NOT in the Supply Fan VFD Bypass mode.
Resolution
1. Make sure that in the VFD settings that parameter 8-01 is set correctly.
Ipak 1
[0] Ctl. Word and digital for Dual DDP Units w/o Bypass (Digit 14= H, J, K, L, M,N, T, V, W, X, Y, Z & Digit 17= 6, 8, A, C) [2] Controlword only for FC, Single, or Dual DDP Units w/ Bypass
Ipak 2 and 3
(2] Controlword only
2. Make sure that Parameter 3-15 is set to [1] Local bus reference
3. Make sure that Parameter 3-02/3-03 are set per nameplates Min/Max Hz settings.
4. Check Diagnostic Log, Parameter 15-30 for VFD Diagnostics. One of the primary seen diagnostics is Broken Belt Alarms.
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.