Furnace Pressure Switch Stuck Open

Furnace Pressure Switch Stuck Open

Cat 06 pg0271 273

= Normally closed switchN.O.= Normally open switchTYPICAL SYSTEM WIRING DIAGRAMThe 50A65-843 is an automatic gas interrupted ignition control that employs a microprocessor to continually monitor, analyze, and control the proper operation of the gas burner, inducer, and fan.Signals interpreted during continual surveillance of the normal operation.These controls incorporate system fault analysis for quick gas a fault correction.Flame Current Requirements: .............Maximum current for non-detection .....................

Maximum allowable leakage resistance .............1 Flame establishing time ......................0.8 seconds maximum Flame failure response time ...............2.0 seconds HELPThe 50A65 has only one serviceable part–an automotive type fuse, which protects the low voltage transformer from damage if its output is short-circuited.

If the fuse has opened up, remove whatever caused the short circuit and replace the fuse with only a 3 Amp automotive type fuse.If the fuse is not the cause of the control’s problem, replace the entire 50A65 control.There are no other user serviceable parts.should be used if the original wiring does not reach the control after mounting.Refer to the furnace wiring diagram for proper connection of the wires.Some applications may require connection to terminal E33 lo-cated in the middle of the contol cover.If the control being re-placed does not have this connection, it is not needed in the application and connection to terminal E33 is not required.Trane application - Jumper wire control) must be installed on the furnace from R02-pin connector.Terminalblock withcaptivescrews12-pinconnector& harness4-pinconnector& harnessspade terminalspade terminalspade terminalspade terminalspade terminalspade terminalspade terminalspade terminalspade terminalspade terminalspade terminalspade terminal3/16" spade COMPONENTCONNECTIONTYPICAL SYSTEM WIRING TABLE* maximum recommended flame probe wire length is 36 inches
furnace pressure switch stuck open
.WGRYCMV (2 terminals)TRTHFPPSHLIHLOGND(3 unused terminal)INDIGNIND NIGN NCOOLHEATPARK (2 terminals)LINEXFMREAC (optional)HUM (optional)CIR NLINE NXFMR NEAC N (optional)HUM N (optional)E33low voltage thermostat W terminal (or equivalent)low voltage thermostat G terminal (or equivalent)low voltage thermostat R terminal (or equivalent)low voltage thermostat Y terminal (or equivalent)(2nd wire from Y terminal goes to 24 VAC HOT side of
compressor contactor coil)24 VAC COMMON side of compressor contactor coilgas valve (both gas solenoids are connected in parallel)24 VAC transformer (low voltage COMMON side)24 VAC transformer (low voltage HIGH side)flame sensor probe*pressure switch INPUThigh limit INPUThigh limit OUTPUTMUST BE RELIABLY GROUNDED TO CHASSISinducer HOT sideignitor HOT sideinducer NEUTRAL sideignitor NEUTRAL sidecirculator blower COOL SPEED terminalcirculator blower HEAT SPEED terminalunused circulator blower terminalsinput voltage (120 VAC) HOT side24 VAC transformer line voltage HOT sideelectronic air cleaner HOT sidehumidifier HOT sidecirculator blower NEUTRAL terminalinput voltage (120 VAC) NEUTRAL side24 VAC transformer line voltage NEUTRAL sideelectronic air cleaner NEUTRAL sidehumidifier NEUTRAL sideAuxiliary flame senseINTEGRATEDFURNACE CONTROLSWIRING HELPOPTION SWITCHES The option switches on the 50A65-843 control are used to determine the length of the cool delay-to-fan-off, heat delay-to-fan-on and heat delay-to-fan-off periods.The following table shows the time periods that will result from the various switch positions.HEAT MODE In a typical system, a call for heat is initiated by closing the thermostat contacts.This starts the 50A65 control’s heating and the 768A silicon nitride ignitor is powered within one second.This control has an adaptive algorithm that reduces the ignitor temperature to slightly greater than the minimum temperature required to ignite gas in each particular application.The con-trol measures the line voltage and determines an initial ignitor temperature setting based on the measurement.After each successful ignition, the control lowers the ignitor temperature slightly for the next ignition attempt.The control continues to lower the ignitor temperature until ignition does not occur, and the control goes into retry mode.

For the second attempt to ignite gas within the same call for heat, the control increases the ignitor temperature to the value it was on the third previ-ous successful ignition.After ignition is successful, the control sets the ignition temperature at this value for the next 255 calls for heat, after which the control repeats the adaptive ignitor temperature to compensate for changes in the line voltage.The 80 VAC Silicon Nitride ignitor manufactured by White-Rodgers must be used.These ignitors are specially designed to operate with the 50A65’s adaptive ignition routine COOL MODE In a typical system, a call for cool is initiated by closing the thermostat contacts.This energizes the 50A65 control and the compressor.

The cool delay-to-fan-on period begins.After the delay period ends, the optional electronic air cleaner is energized, and the circulator fan is energized at cool speed.energized and the cool mode delay-to-fan-off period begins.After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner (optional) are de-energized.MANUAL FAN ON MODE If the thermostat fan switch is moved to the ON position, the circulator fan (cool speed) and optional electronic air cleaner are energized.

When the fan switch is returned to the AUTO position, the circulator fan and electronic air cleaner (optional) are de-energized.SYSTEM LOCKOUT FEATURES When system lockout occurs, the gas valve is de-energiz
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