Hayward IDL2 Fault Code Thumbnails

Brand: Hayward

Model: IDL2

Type: Fault Code Thumbnails

This manual is also suitable for

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 1

Fault Code Thumbnails

FAULT CODE THUMBNAILS

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 2

Heater System Solving Guide

Fault Code Thumbnails AC Blower Vacuum Switch – Failed Closed

FAULT CODE THUMBNAILS AC BLOWER VACUUM SWITCH – FAILED CLOSED

UHS

BLOWER VACUUM SWITCH – FAILED CLOSED

If the blower vacuum switch is closed before blower start-up,

the control module will not start the blower.

Pre-check is executed by the control module.

PARTS THAT MAY BE NEEDED

• Blower Vacuum Switch

• Control Module.

DIAGNOSTIC SEQUENCE

A. Disconnect the blower plug from the control module.

With the heater off, measure the control module receptacle’s

continuity across pins 1 and 2 (UHS, IDL2 & IDL) and pins 3 & 4

(IDL2 & IDL only). If either is closed, replace the control module.

B. If the relay is open, check the vacuum switch. If it is closed,

the blower vacuum switch failed and must be replaced.

IDL

IDL2

FAULT CODE THUMBNAILS – PAGE F 3

Heater System Solving Guide

Fault Code Thumbnails AO Blower Vacuum Switch – Failed Open

FAULT CODE THUMBNAILS AO BLOWER VACUUM SWITCH – FAILED OPEN

UHS

IDL2

IDL

BLOWER VACUUM SWITCH – FAILED OPEN

If the blower vacuum switch opens unexpectedly during operation, the

heater will shut down and attempt to re-light if there is still a call for

heat. If the blower vacuum switch does not close after the blower starts,

the control will stop the ignition trial & go into lockout. The blower will

continue to run for post-purge.

Automatic reset is immediate after the switch closes.

PARTS THAT MAY BE NEEDED

• Blower • Control Module/Ignition Board

• Blower Vacuum Switch • Gray Vacuum Tubing

DIAGNOSTIC SEQUENCE

A. Check for faulty vacuum switch tubing and replace if necessary.

B. Check for faulty vacuum switch wiring or connection. Wire harness

terminals must be securely fastened to spade terminals on vacuum switch.

C. Check for faulty blower wiring or connection. Plug on blower must be

securely fastened to control module.

D. Check for defective vacuum switch by disconnecting blower plug

from control module. Measure resistance across blower windings.

Winding resistance across lead should be in the following range:

IDL: Black to White 30-45 ohms Red to White 90-130 ohms

IDL2: Black to White 10-14 ohms Red to White 18-22 ohms

UHS: Red to White 8-9 ohms

If measured values vary substantially from these values,

the blower is defective and should be replaced.

E. Check for a defective blower relay by disconnecting blower plug from

the control module. Place heater in Pool or Spa mode. Lower set point

temperature to generate call for heat. During pre-purge period, measure

for 120VAC across pins 1 and 2 (UHS & IDL2) or L1 & IND low (IDL).

If 120VAC is not present, the control module relay is defective, which

means the control module must be replaced.

F. If the above steps do not resolve the problem (the error still exists),

the vacuum switch is defective and must be replaced.

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 4

Heater System Solving Guide

Fault Code Thumbnails BD Bad Board or Secondary High Voltage Fault

FAULT CODE THUMBNAILS BD BAD BOARD OR SECONDARY HIGH VOLTAGE FAULT

UHS

IDL2

BAD BOARD

SECONDARY HIGH VOLTAGE FAULT

PARTS THAT MAY BE NEEDED

• Control Module / Ignition Board

• Extra Fuses

• Fuse Board

• Wiring Harness

• Transformer

DIAGNOSTIC SEQUENCE

A. Verify that FC4 fuse on fuse board is not open. Remove FC from fuse-

holder. Measure continuity across fuse. If OK, reinstall fuse and proceed

to step 2. If fuse is open, proceed to section titled “Open FC4 Fuse”.

B. Verify high voltage output from fuse board. Disconnect plug from P6

connector of fuse board. Measure for 120VAC across pins 3 and 5 of

P6 receptacle on fuse board. If OK, reconnect plug and proceed to step

3. If not OK, go to step 4.

C. Check for defective wiring harness. Disconnect plug from E10 connector

of contol module. Measure for 120VAC across pins 1 and 3 of plug on

wiring harness. If OK, replace control module. If not OK, replace wiring

harness.

D. Check for defective transformer. Disconnect plug from P4 connector of

fuse board. Measure for 120VAC between pins 4 and 6 of plug from

transformer. If OK, proceed to step 5. If not OK, replace transformer.

E. If the above steps have not resolved the error condition, the fuse board

is defective and must be replaced.

NOTE: Red letters above correspond with adjacent illustrations.

FAULT CODE THUMBNAILS – PAGE F 5

Heater System Solving Guide

Fault Code Thumbnails BO Bypass Operation (for external controls)

FAULT CODE THUMBNAILS BO BYPASS OPERATION (FOR EXTERNAL CONTROLS)

BYPASS OPERATION (FOR EXTERNAL CONTROLS)

UHS, IDL2, IDL, ED2

The “bo” code is more of an information code than a fault code,

with the “bo” standing for Bypass Operation.

A “bo” code indicates the heater’s internal thermistor is disabled,

allowing the external thermostat control to operate.

This prevents any confusion between the two temperature-sensing

devices during heater operation — though the heater’s thermistor

will still prevent the heater for exceeding 104

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 6

Heater System Solving Guide

Fault Code Thumbnails CE Communication Error

FAULT CODE THUMBNAILS CE COMMUNICATION ERROR

UHS

IDL2

COMMUNICATION ERROR

PARTS THAT MAY BE NEEDED

• Control Module/Ignition Board

•. Display Board

• Membrane Switch/Keypad.

ERROR DETAIL: COMMUNICATION ERROR

BETWEEN CONTROL MODULE & DISPLAY INTERFACE ASSEMBLY

If communication between the ignition board and the display board is

not established within 3 seconds of power-up, an error will be displayed.

After communication is established, if it is lost for 30 seconds, the er-

ror will be displayed. The error code will be cleared upon a valid data

exchange between boards..

DIAGNOSTIC SEQUENCE

A. Power down heater and re-power. This is similar to rebooting a com-

puter.

B. If rebooting does not solve the problem, inspect the display interface

wiring. Ensure the display interface plug is securely attached to the

control module.

C. If steps A & B do not resolve the CE error, the control module and/or

display interface assembly are defective and must be replaced.

FAULT CODE THUMBNAILS – PAGE F 7

Heater System Solving Guide

Fault Code Thumbnails EE Electrical Error

FAULT CODE THUMBNAILS EE ELECTRICAL ERROR

ELECTRICAL ERROR

PARTS THAT MAY BE NEEDED

• Control Module / Ignition Board

DIAGNOSTIC SEQUENCE

Replace the Control Module / Ignition Board.

UHS

IDL2

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 8

Heater System Solving Guide

Fault Code Thumbnails HF NEW: Gas Valve Fault or OLD: Heater Flame Sensing Fault

FAULT CODE THUMBNAILS HF FLAME PRESENT WITH GAS VALVE CLOSED / HEATER FLAME SENSING FAULT

UHS

IDL2

ED2

IDL

HEATER FLAME SENSING FAULT

IDL, ED2

PARTS THAT MAY BE NEEDED

• Ignitor / Flame Sensor

• Control Module / Ignition Board

DIAGNOSTIC SEQUENCE

A. Check all wiring and connections for Flame sensor.

B. Replace flame sensor (IDL) or ignitor (ED2).

C. Replace control module/ignition board if problem still exists.

FLAME PRESENT WITH GAS VALVE CLOSED

UHS, IDL2

PARTS THAT MAY BE NEEDED

• Gas Valve

If flame is sensed without the gas valve energized, the control will go

into lockout.

DIAGNOSTIC SEQUENCE

• SHUT OFF GAS TO HEATER IMMEDIATELY.

• The gas valve is defective and needs to be replaced.

RIGHT: HF INDICATES A FLAME SENSING FAULT ON OLDER MODELS (IDL, ED2)

BELOW: HF INDICATES A GAS VALVE FAULT ON NEWER MODELS (UHS, IDL2)

FAULT CODE THUMBNAILS – PAGE F 9

Heater System Solving Guide

Fault Code Thumbnails HS Maximum Return Water Temp Exceeded

FAULT CODE THUMBNAILS HS MAXIMUM RETURN WATER TEMP EXCEEDED

MAXIMUM RETURN WATER TEMPERATURE EXCEEDED

UHS, IDL2, IDL, ED2

If water temperature exceeds 105°F, the heater will shut down and

go into lock-out.

Automatic restart is 2 minutes after water temp drops below 105°F.

PARTS THAT MAY BE NEEDED

• Control Module

• External Thermostat (if system uses one)

NOTE: In most cases, no replacement part will be needed.

DIAGNOSTIC SEQUENCE

A. Verify water flow is adequate.

Low water flow will cause high temperature.

(Generally, 25 gpm is needed by smaller heaters, while 300,000 btu/h

heaters may require 40 gpm or more. See heater’s operating manual.)

B. Verify set point setting of remote thermostat us below 108°F. If external

control is used, verify that external thermostat is set below 104

F. (Exter-

nal thermostat may be faulty and need to be replaced.)

C. Verify integrity of exchanger.

D. Check for possible bad ignition/control module.

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 10

Heater System Solving Guide

Fault Code Thumbnails IF Ignition Failure

FAULT CODE THUMBNAILS IF IGNITION FAILURE (INSUFFICIENT FUEL)

IGNITION FAILURE

(INSUFFICIENT FUEL)

UHS, IDL2, IDL, ED2

REQUIRED DIAGNOSTIC TOOLS

• Manometer

• Multimeter

PARTS THAT MAY BE NEEDED

• Flame Sensor

• Ignitor

• Ignition Board / Control Module

• Gas Valve

While IF actually stands for Ignition Failure, this code is often

referred to as the Insufficient Fuel code – since the most common

reason for an “IF” code is inadequate gas supply to the heater.

—————

“IF” occurs when the heater passes all safety checks but the heater fails to

ignite.

Without the proper gas/air mixture, the heater will not light. Since the

heater has gone through most of the steps within the Sequence of Op-

eration, the problem is most likely gas supply or a faulty ignition board,

flame sensor, ignitor or gas valve.

Investigate and ensure that the gas train is correct.

The source of an IF code is found in the gas train 90% of the time.

DIAGNOSTIC SEQUENCE

A. Ensure that main gas shutoff adjacent to heater is open. Ensure that

knob on gas valve inside unit is in ‘‘on’’ position. If OK, proceed to

next step.

B. Check for low gas supply pressure by ensuring inlet gas supply pres-

sure is between the minimum and maximum values indicated on rating

plate. If OK, proceed to next step.

C. Inspect flame sense wiring, and ensure wire harness terminals are se-

curely fastened to flame sense and to control module. If OK, proceed

to next step.

D. Inspect gas valve wiring, and ensure wire harness terminals are se-

curely fastened to spade terminals on gas valve. If OK, proceed to next

step.

E. Check for gas valve failure or gas valve relay failure.1. Measure volt-

age across gas valve during trial for igintion.

I. If 24VAC is present and gas valve does not open, gas valve is de-

fective and must be replaced.2.

II. If 24VAC is not present, gas valve relay on control module is defec-

tive, which means the control module must be replaced.

F. Inspect gas orifices for blockages that could prevent gas flow. Also re-

move and inspect burners for blockages.

FAULT CODE THUMBNAILS – PAGE F 11

Heater System Solving Guide

Fault Code Thumbnails IO Ignitor Failure

FAULT CODE THUMBNAILS IO IGNITOR FAILURE

IGNITOR FAILURE

PARTS THAT MAY BE NEEDED

• Ignitor

• Control Module / Ignition Board

DIAGNOSTIC SEQUENCE

A. Check for faulty wiring or connection.

B. Replace ignitor.

C. Replace Control Module/Ignition Board

NOTE: Red letters above correspond with adjacent illustrations.

IDL2

UHS

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 12

Heater System Solving Guide

Fault Code Thumbnails LO Switch Open within Safety Limit String

UHS

(SEE PAGE F13)

IDL2

(SEE PAGE F13)

IDL

(SEE PAGE F14)

ED2

(SEE PAGE F15)

FAULT CODE THUMBNAILS LO SWITCH OPEN WITHIN SAFETY LIMIT STRING

LO SWITCH OPEN WITHIN SAFETY LIMIT STRING

FAULT CODE THUMBNAILS – PAGE F 13

Heater System Solving Guide

Fault Code Thumbnails LO Switch Open within Safety Limit String (UHS, IDL2)

SWITCH OPEN WITHIN SAFETY LIMIT STRING

UHS, IDL2

PARTS THAT MAY BE NEEDED

• High Limit Switches • Control Module

• (Water) Pressure Switch • Wiring Harness

• Vent Pressure Switch

NOTE: “lo” is normal when pump is off. Otherwise, “lo” means a con-

trol loop switch is open. Therefore, check for the following:

DIAGNOSTIC SEQUENCE

Possibility 1: Water Pressure Switch Fault

A. To verify that the pump is running, turn the pump OFF and watch to see that

the LO code clears. If LO does not clear, proceed to next step.

B. Verify that water flow rate to heater is above minimum required:

20 GPM for H150--- and H200---,

25 GPM for H250--- and H300---,

30 GPM for H350--- and H400---.

If OK, proceed to next step.

C. Check the water pressure switch for faulty wiring and connections: Ensure

wire harness terminals are securely fastened to spade terminals on water

pressure switch. If OK, proceed to next step.

D. Verify the state of water pressure switch contacts: Remove wire leads from

water pressure switch and jumper leads. Then attempt to operate the heat-

er, measuring continuity across water pressure switch. If closed, LO code is

not caused by water pressure switch fault. If open, proceed to next step (af-

ter removing jumper from wire leads and reconnecting wire leads to water

pressure switch).

E. Ensure that low pump pressure does not exist. Clean filter or clear block-

ages. Check position of valves in plumbing system. If OK proceed to next

step.

F. Adjust water pressure switch setting as shown on page 33 of UHS Installa-

tion Manual (only if heater is above or below water level). If LO does not

clear, the water pressure switch is defective and must be replaced.

DIAGNOSTIC SEQUENCE (CONTINUED)

Possibility 2: Vent Pressure Switch Fault

(For UHS indoor installations only)

G. Check the vent pressure switch for faulty wiring and connections: En-

sure wire harness terminals are securely fastened to spade terminals on

vent pressure switch. If OK, proceed to next step.

H. Verify the state of vent pressure switch contacts: Remove wire leads from

vent pressure switch and jumper leads. Then attempt to operate the

heater, measuring continuity across vent pressure switch. If closed, LO

code is not caused by vent pressure switch fault. If open, proceed to next

step (after removing jumper from wire leads and reconnecting wire leads

to vent pressure switch).

I. Ensure that flue is not blocked or restricted: See indoor vent sizing re-

quirements in installation manual. If OK, the vent pressure switch is

defective and must be replaced.

Possibility 3: High Limit Switch Fault

J. Check the high limit switch for faulty wiring and connections: Ensure

wire harness terminals are securely fastened to spade terminals on high

limit switch. If OK, proceed to next step.

K. Verify the state of high limit switch contacts: Remove wire leads from

high limit switch and jumper leads. Then attempt to operate the heater,

measuring continuity across the high limit switch. If closed, LO code

is not caused by a high limit switch fault. If open, proceed to next step

(after removing jumper from wire leads and reconnecting wire leads to

high limit switch).

L. Verify that water flow rate to heater is above minimum required:

20 GPM for H150--- and H200---,

25 GPM for H250--- and H300---,

30 GPM for H350--- and H400---.

If OK, the high limit switch is defective and must be replaced.

Finally, remember that the problem could exist

in the wiring harness and also the control module.

FAULT CODE THUMBNAILS LO SWITCH OPEN WITHIN SAFETY LIMIT STRING (UHS, IDL2)

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 14

Heater System Solving Guide

Fault Code Thumbnails LO Switch Open within Safety Limit String (IDL)

SWITCH OPEN WITHIN SAFETY LIMIT STRING

IDL

PARTS THAT MAY BE NEEDED

• High Limit Switches • Control Module

• (Water) Pressure Switch • Wiring Harness

• Vent Pressure Switch

NOTE: “lo” is normal when pump is off. Otherwise, “lo” means a

control loop switch is open. Therefore, check for the following:

DIAGNOSTIC SEQUENCE

Possibility 1: Water Pressure Switch Fault

A. To verify that the pump is running, turn the pump OFF and watch to

see that the LO code clears. If LO does not clear, proceed to next step.

B. Verify that water flow rate to heater is above minimum required:

20 GPM for H150--- and H200---,

25 GPM for H250--- and H300---,

30 GPM for H350--- and H400---.

If OK, proceed to next step.

C. Check the water pressure switch for faulty wiring and connections:

Ensure wire harness terminals are securely fastened to spade terminals

on water pressure switch. If OK, proceed to next step.

D. Verify the state of water pressure switch contacts: Remove wire leads

from water pressure switch and jumper leads. Then attempt to oper-

ate the heater, measuring continuity across water pressure switch. If

closed, LO code is not caused by water pressure switch fault. If open,

proceed to next step (after removing jumper from wire leads and re-

connecting wire leads to water pressure switch).

E. Ensure that low pump pressure does not exist. Clean filter or clear

blockages. Check position of valves in plumbing system. If OK pro-

ceed to next step.

F. Adjust water pressure switch setting per instructions in IDL Installation

Manual (only if heater is above or below water level). If LO does not

clear, the water pressure switch is defective and must be replaced.

DIAGNOSTIC SEQUENCE (CONTINUED)

Possibility 2: Terminal Block Fault

G. Check if a remote on/off device connected to terminal block is open: Turn

remote device on, and watch for LO code to clear. If LO does not clear,

go to step I. If a remote on/off device is not connected to heater, go to step H.

H. Verify that jumper has been removed: If remote on/off control is not used, the

two far-right terminals of terminal block should be jumpered. If jumper is not

present. add jumper. Then, if LO code does not clear, proceed to next step.

I. Inspect terminal block wiring. Ensure wire harness terminals are securely

fastened to terminal block. If OK, terminal block is defective and should be

replaced.

Possibility 3: Vent Pressure Switch Fault

J. Check the vent pressure switch for faulty wiring and connections: Ensure wire

harness terminals are securely fastened to spade terminals on vent pressure

switch. If OK, proceed to next step.

K. Verify the state of vent pressure switch contacts: Remove wire leads from vent

pressure switch and jumper leads. Then attempt to operate the heater, mea-

suring continuity across vent pressure switch. If closed, LO code is not caused

by vent pressure switch fault. If open, proceed to next step (after removing

jumper from wire leads and reconnecting wire leads to vent pressure switch).

L. Ensure that flue is not blocked or restricted: See indoor vent sizing require-

ments in installation manual. If OK, the vent pressure switch is defective and

must be replaced.

Possibility 4: Temperature Limit Switch Fault

M. Check the high limit switch for faulty wiring and connections: Ensure

wire harness terminals are securely fastened to spade terminals on high

limit switch. If OK, proceed to next step.

N. Verify the state of high limit switch contacts: Remove wire leads from

high limit switch and jumper leads. Then attempt to operate the heater,

measuring continuity across the high limit switch. If closed, LO code

is not caused by a high limit switch fault. If open, proceed to next step

(after removing jumper from wire leads and reconnecting wire leads to

high limit switch).

O. Verify that water flow rate to heater is above minimum required:

20 GPM for H150--- and H200---,

25 GPM for H250--- and H300---,

30 GPM for H350--- and H400---.

If OK, the high limit switch is defective and must be replaced.

Finally, remember that the problem could exist

in the wiring harness and also the control module.

FAULT CODE THUMBNAILS LO SWITCH OPEN WITHIN SAFETY LIMIT STRING (IDL)

FAULT CODE THUMBNAILS – PAGE F 15

Heater System Solving Guide

Fault Code Thumbnails LO Switch Open within Safety Limit String (ED2)

SWITCH OPEN WITHIN SAFETY LIMIT STRING

ED2

PARTS THAT MAY BE NEEDED

• High Limit Switches • Control Module

• (Water) Pressure Switch • Wiring Harness

• Vent Pressure Switch

NOTE: “lo” is normal when pump is off. Otherwise, “lo” means a

control loop switch is open. Therefore, check for the following:

DIAGNOSTIC SEQUENCE

Possibility 1: Water Pressure Switch Fault

A. To verify that the pump is running, turn the pump OFF and watch to

see that the LO code clears. If LO does not clear, proceed to next step.

B. Check the water pressure switch for faulty wiring and connections:

Ensure wire harness terminals are securely fastened to spade terminals

on water pressure switch. If OK, proceed to next step.

C. Verify the state of water pressure switch contacts: Remove wire leads

from water pressure switch and jumper leads. Then attempt to oper-

ate the heater, measuring continuity across water pressure switch. If

closed, LO code is not caused by water pressure switch fault. If open,

proceed to next step (after removing jumper from wire leads and re-

connecting wire leads to water pressure switch).

D. Ensure that low pump pressure does not exist. Clean filter or clear

blockages. Check position of valves in plumbing system. If OK pro-

ceed to next step.

E. Adjust water pressure switch setting per instructions in IDL Installation

Manual (only if heater is above or below water level). If LO does not

clear, the water pressure switch is defective and must be replaced.

DIAGNOSTIC SEQUENCE (CONTINUED)

Possibility 2: Automatic Temperature Limit Switch Fault

F. Check the (automatic) temperature limit switch for faulty wiring and connections:

Ensure wire harness terminals are securely fastened to spade terminals on the

temp limit switch. If OK, proceed to next step.

G. Verify the state of (automatic) temperature limit switch contacts: Remove wire

leads from (automatic) temp limit switch and jumper the leads. Then attempt to

operate the heater, measuring continuity across (automatic) temp limit switch.

If closed, LO code is not caused by (automatic) temperature limit switch fault.

If open, proceed to next step.

H. OUTDOOR UNITS ONLY: Check for high winds or severe downdrafting and, if

necessary, install High Wind Stack. (For indoor units, skip ahead to next step.)

I. Ensure that flue is not blocked or restricted: Refer to vent sizing requirements.

J. Check for sooted or damaged exchanger. If sooted or damaged, the exchanger

should be cleaned (and may need to be replaced).

Possibility 3: Manual Temperature Limit Switch Fault

K. Repeat steps F through J for manual temperature limit switch.

L. Reset manual temperature limit switch. If switch continues to trip, replace the

manual temperature limit switch.

Possibility 4: High Limit Switch Fault

M. Check the high limit switch for faulty wiring or connections. Ensure wire harness

terminals are securely fastened to spade terminals.

N. Verify state of high limit contacts. Remove wire leads from high limit switches

and jumper leads. Operate heater, and measure continuity across high limit

switches. If closed, LO code is not caused by high limit switch fault. If open, re-

move jumper from leads, reconnect leads to high limit switches, and proceed to

next step.

Possibility 5: Inadequater Water Flow Fault

Q. Verify that water flow rate to heater is above minimum required: 25 GPM.

R. At this point, it must be assumed that a high limit switch is faulty and must be

replaced.

FAULT CODE THUMBNAILS LO SWITCH OPEN WITHIN SAFETY LIMIT STRING (ED2)

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 16

Heater System Solving Guide

Fault Code Thumbnails SB Keypad Failure

FAULT CODE THUMBNAILS SB KEYPAD FAILURE

UHS IDL2

KEYPAD FAILURE

PARTS THAT MAY BE NEEDED

• Keypad/Membrane Switch

DIAGNOSTIC SEQUENCE

A. Replace keypad/membrane switch.

FAULT CODE THUMBNAILS – PAGE F 17

Heater System Solving Guide

Fault Code Thumbnails SF Temperature Sensor Input Failure

FAULT CODE THUMBNAILS SF TEMPERATURE SENSOR INPUT FAILURE

IDL

UHS

IDL2

ED2

TEMPERATURE SENSOR INPUT FAILURE

PARTS THAT MAY BE NEEDED

• Thermistor

• Control Module

DIAGNOSTIC SEQUENCE

A. Check where the thermistor connects

to the board to see if it has become disconnected or damaged.

B. Replace thermistor if wire or connection is damaged.

C. Replace control module if connection on board is damaged

D. Replace control module if new thermistor does not correct fault.

Heater System Solving Guide

FAULT CODE THUMBNAILS – PAGE F 18

Heater System Solving Guide

Fault Code Thumbnails Fault Conditions with NO CODE

FAULT CODE THUMBNAILS FAULT CONDITIONS WITH NO CODE

FAULT CONDITIONS WITH NO CODE

UHS, IDL2

PARTS THAT MAY BE NEEDED

• Fuses (FC1, FC2, FC3, FC4) • Transformer

• Fuse Board • Control Module

• Wiring • Wiring Harness

DIAGNOSTIC SEQUENCE

Heater Will Not Power Up

A. Verify that low & high voltage is being output from fuse board:

Disconnect the P5 connector from fuse board plug, and measure for

24vac between pins on fuse board receptacle. Reconnect the P5 plug, and

disconnect P6 connector plug on the fuse board. Measure for 120VAC

between pin 3 and 6 of receptacle on fuse board.

If OK, reconnect P6 plug and proceed to next fault condition, Low

Voltage Circuit Fault.

Otherwise, reconnect P6 plug and proceed to step B.

B. Verify heater is getting field power by measuring for field supply voltage

across terminals of TB1 terminal block on fuse board.

C. Inspect fuse board wiring, and ensure all plugs are securely fastened to

fuse board.

D. Remove FC1 and FC2 fuses from fuseholder. Measure continuity across

fuse.

If fuses are open, proceed to fault condition Open Fuse: FC2 or F1.

If fuses are OK, reinstall them and proceed to step E.

E. Check that the proper voltage selector plug is installed in fuse board.

F. Disconnect P4 connector from fuse board plug. Measure for 24VAC

between pins 1 & 2 of plug of transformer and for 120VAC between pins

4 & 6.

If 24VAC or 120VAC is not present, replace transformer.

Otherwise, replace fuse board.

Low Voltage Circuit Fault

G. Disconnect P5 connector from fuse board plug. Measure for 24VAC

across pins. Reconnect plug.

If OK, proceed to step H. Otherwise proceed to step K.

H. Inspect control module wiring. Ensure all plugs are securely fastened to

control module.

I. Verify 24VAC across R and C terminals on control module.

If not OK, replace harness.

J. Remove F1 fuse from fuseholder. Measure continuity across fuse.

If OK, replace control module.

If fuse is open, proceed to fault condition Open Fuse: FC3 or F1.

K. Remove FC3 fuse from fuseholder. Measure continuity across fuse.

If fuse is open, proceed to fault condition Open Fuse: FC3 or F1.

If OK, reinstall fuse and proceed to step L.

L. Disconnect P4 connector from fuse board plug. Measure for 24VAC

between pins 1 & 2 of plug from transformer. If 24VAC is not present,

replace the transformer. Otherwise, replace fuse board.

Open Fuse: FC2 or FC1

M. Check that proper voltage selector plug is installed.

N. If 120VAC plug is installed but field supply voltage is 240VAC, FC1 and

FC2 fuses will have opened. Install the correct voltage selector plug

(240VAC) and new FC1 and FC2 fuses.

O. Inspect transformer wiring. Ensure insulation on wiring is not worn.

If OK, replace the transformer.

Open Fuse: FC3 or FC1

P. Inspect gas valve wiring. Ensure insulation on wiring is not worn.

Q. Measure for resistance across gas valve terminals and between each ter-

minal and ground. If short exists, replace gas valve.

R. Inspect control module wiring. Ensure insulation on wiring is not worn.

If OK, replace the control module.

Open Fuse: FC4

S. Inspect ignitor wiring. Ensure insulation on wiring is not worn.

T. Inspect blower wiring. Ensure insulation on wiring is not worn.

U. Disconnect ignitor plug from control module. Measure resistance across

Igniter. If shorted, replace ignitor.

V. Disconnect blower plug from control module. Measure resistance across

blower windings. Winding resistance across lead should be in the following

range:

IDL2: Black to White 10-14 ohms Red to White 18-22 ohms

UHS: Red to White 8-9 ohms

If measured values vary substantially from these values, blower is defective

and must be replaced. Otherwise, replace the control module.

Hayward IDL2 Fault Code Thumbnails

Brand: Hayward

Model: IDL2

Type: Fault Code Thumbnails

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Hayward IDL2 Fault Code Thumbnails

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