Timers
Delays not timing, contacts not switching.
Timer relay not switching its output
A timer relay is powered but its output contact never changes state — the delayed action (start, changeover, stop) never happens, or it switches at the wrong time.
Timer times out too long or too short
The timer switches, but at the wrong time — the delay is much longer or shorter than it should be, throwing out the sequence.
Timer resets part-way through timing
The timer starts but resets before it finishes, so it never completes — the delayed action keeps getting cancelled and never happens.
Timer output chatters or pulses at changeover
When the timer reaches its set point, the output chatters or pulses instead of switching cleanly, causing the downstream device to buzz or operate erratically.
Timer completely dead (no power / no display)
The timer shows no signs of life — no display, no LED, no output activity — so nothing it controls will ever operate.
Timer behaving as the wrong type (on-delay vs off-delay)
The timer switches at the wrong point in the sequence because it's acting as the wrong function — on-delay where off-delay is needed, single-shot where cyclic is needed, and so on.
Time clock / programmable timer not switching its load
A time clock (lighting, heating, ventilation) isn't switching at the programmed times — the load stays on or off regardless of the schedule.