Settings shortcuts: Furnace tips

Short, practical technician tips on settings shortcuts for furnace. Check each one against the manual for your exact model before acting.

Change a value in the 3-digit display menu

Carrier · 59SC6A, Payne PG96VTA and 59MN7C furnaces (3-digit display control)

Same method for every menu item (for example HoD, Cod, dir, tnn): scroll, step the value, save.

1. Press MENU/SELECT to scroll the main menu to the item
2. Press NEXT/OPTION to show the current value (it flashes) and step through the choices
3. Press MENU/SELECT to save; the display flashes three times to confirm

Show supply and return air temperature on the display (59MN7C)

Carrier · 59MN7C modulating furnace

The t° menu item turns on a rotating display of mode, supply air temperature (SAT), return air temperature (RAT) and the difference. Default is off; it only shows while heating, cooling or heat pump operation is running.

1. Scroll to t° in the main menu
2. Choose F or C (or off)
3. If the displayed SAT does not agree with a thermometer, move the SAT sensor further from the furnace or past a bend in the duct

Turn off R-32 monitoring when no R-32 system is fitted (A2E)

Daikin · Daikin DR96TN and DD96TN two-stage 96% furnaces

If the furnace has no R-32 coil and sensor, A2E must be set to no; otherwise the furnace drops into fan-only mitigation.

1. Press the left or right switch to scroll to the A2E menu item.
2. Press the center switch to open it.
3. Choose no and press the center switch to save.

Turn on dehumidification

Goodman · GMVC95/AMVC95 upflow and *CVC9 counterflow two-stage furnaces

Blower drops to about 82% of the cooling speed on a combined cool + dehumidify call.

1. Power off.
2. Wire a 24 V dehumidistat that opens on humidity rise: neutral to DEHUM, hot to R, ground to the junction box screw.
3. Set S5 switch 9 ON.
4. On non-communicating systems jumper Y1 to DEHUM (and Y1 to O for ramping profiles).
5. Power back on.

Use a single-stage thermostat (timed staging)

Goodman · GMVC95/AMVC95 upflow and *CVC9 counterflow two-stage furnaces

With a single-stage stat the furnace runs low fire first and steps to high fire on a timer.

1. Power off.
2. S1 switch 3 OFF = single-stage thermostat (ON = two-stage).
3. S1 switch 4 OFF = fixed 5 minute step-up, ON = auto (1-12 minutes based on the last 3 cycles).
4. Power back on.

Cut the cooling blower off-delay to 5 seconds (9MAE)

ICP · (F/G)9MAE0601714A, 0602120A, 0801714A, 0802120A, 1002122A, 1202422A

Cooling off-delay is 90 s; jumpering Y (or Y1) to DHUM cuts it to 5 s.

1. Jumper Y (or Y1) to the DHUM terminal
2. Cooling blower off-delay drops from 90 s to 5 s

Cut the cooling blower off-delay to 5 seconds (9MXE)

KeepRite · KeepRite (F/G)9MXE

The cooling blower off-delay is 90 s; jumpering Y/Y2 or Y1 to DHUM cuts it to 5 s. The DHUM input logic is reversed: 24 V means no dehumidify call.

1. Jumper Y/Y2 or Y1 to the DHUM terminal on the control
2. Cooling blower off-delay then drops from 90 s to 5 s

Codes look upside down - display orientation switch S1-1

Rheem · (-)96VA040-115 (R96V / U96V) and (-)(-)96MDV040-115 two-stage variable-speed communicating furnaces

The control is used in upflow and downflow cabinets, so the display can be flipped. If a code is not on the list, it is probably being read upside down.

1. S1-1 OFF = upflow (as shipped), ON = downflow.
2. Set it to match the furnace position before reading fault codes.

Heat anticipator setting

Trane · Room air thermostat

Set the room thermostat heat anticipator to match the current measured.

1. Measure the control current flow.
2. Set the thermostat heat anticipator to that value, or to the value in the wiring diagram notes (found in Service Facts or inside the furnace casing).