Mars Sequencer Replacement W-R 24A34-1 M33841

The Mars M33841 is an electric heat sequencer, replacing the White-Rodgers 24A34-1.

Diagnosing electric heat problems benefits from understanding the sequence in which things happen.

On a call for electric heat, the sequencer's internal heater is energised from the control circuit. The bimetal warms over a period of typically twenty to sixty seconds, and its contacts close, energising the heating element and, on sequencers with multiple contact sets, the blower.

When the call ends, the sequencer's heater is de-energised, the bimetal cools, and the contacts open after a similar delay. That trailing delay is deliberate: it keeps the blower running after the elements de-energise, clearing residual heat from the assembly.

Faults present recognisably. A sequencer whose contacts have failed open produces a stage of heat that never comes on. Contacts welded closed produce a stage that runs continuously. A failed internal heater produces the same symptom as open contacts.

Checking for voltage at the sequencer's heater terminals during a call, and then for continuity across the load contacts after the delay, separates these.

Applications include electric furnaces, air handlers with electric heat, and heat pump supplemental heat.

Brand

Mars

SKU

M33841

Category

Sequencers

Weight

0.35 lbs

Dimensions

3.50" x 2.50" x 2.00"

Price

$18.00

Availability

In stock

Rating

4.3 / 5.0