Carrier 48HDT User Manual

Page 22

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open) closes, energizing the heat motor in the main
gas valve. The main gas valve will open within
45 seconds.

Main Burners are factory set and should require
no adjustment. However, if burner adjustment is
necessary:

1. Perform Automatic Pilot Adjustment.

2. Turn gas valve to ON. Allow unit to operate at

least 15 minutes with furnace access panel in
place.

3. Remove access panel.

4. Loosen primary air shutter and adjust to a mini

mum opening of 5/8 inch.

5. Retighten primary air shutter and reinstall access

panel.

TO CHECK ignition of main burners and fan
switch operation, move thermostat dial above and
below room temperature several times pausing at
least one minute between cycles.

REMOVAL

1. Shut off manual main gas valve.

2. Shut off power to unit.
3. Remove evaporator air fan access panel, burner

compartment access panel and center post.

4. Disconnect gas piping at unit gas valve.

5. Remove (and mark) red wire from terminal no. 4

or W1 and brown wire from terminal no. 3 or C2
and violet wire from terminal W2 (connections
are dependent on whether a 2-stage or single-
stage valve is on the unit).

6. Remove the 2 screws at rear of housing just

inside burner section.

7. Lift and slide assembly out.

REPLACEMENT

1. Slide assembly into burner section and push

snugly against vestibule plate.

2. Screw assembly down.
3. Connect red wire to terminal no. 4 or W1 and

brown wire to terminal no. 3 or C2 and violet
wire to terminal W2 (connections are dependent
on whether a 2-stage or single-stage valve is on
the unit).

4. Connect gas piping at unit gas valve.

5. Replace center post and access panels.
6. Turn on manual main gas valve.
7. Restore power to unit.

CLEANING

1. Remove burner assembly from unit as described

above.

2. Inspect burners and if dirty, remove by removing

retaining plate.

3. Using a soft brush clean burners as required.

4. Replace burners.

5. Replace burner assembly as described above.
Replacement Parts — A complete list of replace
ment parts may be obtained from any Carrier dis
tributor upon request.