1 Thetford Refrigerator N90 Troubleshooting Fridges

User Manual: Thetford Refrigerator N90

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Thetford Fridge terminology

Product lines

• DeLuxe line refrigerators with control knobs

All refrigerators which are supplied WITHOUT the LCD display control panel.

Manual Energy Control (MEC) Piëzo (V85) Manual Energy Control (MEC) Piëzo

Manual Energy Control (MEC) Electronic Manual Energy Control (MEC) Electronic

Isphording

• DeLuxe line refrigerators with LED

Smart Energy Selection (SES) LED

• Premium LCD line refrigerators

All refrigerators which are supplied WITH the LCD display control panel.

Either Electronic Energy Selection (EES) or Smart Energy Selection (SES) Automatic

Press the left button (mode selection switch), when you see Auto on the left

side of the display you have a SES version when not, you have an EES

version

Error code 1

AC heater current is measured to

be 75% below nominal current

AC Input issue

Check if the 5A fuse

is OK

No

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

YesYes

Yes

Check if the heater

impedance is correct

(in Ohm)

Yes

Replace the AC

heater

(see Spare Parts

List)

Input supplied at the

fridge is stable and

included between

210V and 240V

No Change the fuse

(part 624030)

Type Min Max

N90-N97-

N98-N100-

N104-N109-

N112-N115

312Ω380Ω

N145-N150-

N175-N180 218Ω266Ω

No

Error code 2

DC heater current is measured to

be 75% below nominal current

DC input issue

Check if all the

connections are OK

No

YesYes

Check if the D+

input is included

between 9.5V and

15.5V

Yes

Input supplied at the

fridge is stable and

included between

9.5V and 15.5V

No Restore the

connections

D+ input issue

No

Check if the 20A

fuse is OK

Yes

No Change the fuse

(part 626996)

Yes

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Yes

Check if the heater

impedance is correct

(in Ohm) Replace the DC

heater

(see Spare Parts

List)

Type Min Max

N90-N97-

N98-N100-

N104-N109-

N112-N115

0.93Ω1.13Ω

N145-N150-

N175-N180 0.88Ω1.08Ω

No

Error code 3

AC heater is ON when it should be

OFF

AC input issue

No

YesYes

Input supplied at the

fridge is stable and

included between

210V and 240V

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

DC input issue

No

YesYes

Input supplied at the

fridge is stable and

included between

9.5V and 15.5V

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Error code 4

DC heater is ON when it should be

OFF

Check if the D+

input is included

between 9.5V and

15.5V and if polarity

is correct

D+ input issue

No

Yes

Error code 5

Senses flame when gas should be

OFF

Replace Power board: - SES version part 631219

- EES version part 631220

Error code 6

Senses gas output terminal ON

when should be OFF

Replace Power board: - SES version part 631219

- EES version part 631220

Error code 7

Senses gas output terminal OFF

when should be ON

Replace the gas

valve

No

YesYes

Check if the gas

valve works

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Error code 8

AC mains supply is below 20%

nominal

AC input issue

No

YesYes

Input supplied at the

fridge is stable and

included between

210V and 240V

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Check if the 5A

glass fuse is OK

Yes

No Change the fuse

(part 624030)

Error code 9

Gas lockout because flame

fails to ignite after 30 seconds

Check if there is

gas to the fridge Ensure there is gas

in the cylinder & that

it is turned on along

with all isolation tops

Check if the gas

lights

Check if the spark

continues

No

No

Check electrode

connections & look

for damages

Replace electrode

No

Yes

Yes

Check if there

is a spark

Check if the

electrode gap is set

at about 4 mm

above the burner

Yes

No

Adjust the electrode

gap to approx. 4 mm

No

Yes

No

Yes

Check if the

gas valves

opens

Yes

Replace the gas

valve

No

No

No

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Injector of the burner

is clean. Flame is

dense and blue. Clean the burner and

the injector. Replace

the burner in case of

bad combustion

(see Spare Parts

List)

Yes

No

Check if the gas

pressure is between

28 and 30 mb

Yes

Yes

No

Yes

Check the gas

installation

No

Error code 10

“No engine running” signal is

Present and control is in Manual DC

mode

To know if D+ polarity is good, select manually DC

mode engine off.

If no error code occurs, that means the D+ input is

versed.

Ensure power supply is capable to supply correct

amperage.

DC input issue

No

YesYes

Input supplied at the

fridge is stable and

included between

9.5V and 15.5V

Check if the D+

input is included

between 9.5V and

15.5V and if polarity

is correct

D+ input issue

No

Yes

Check if the 20A

fuse is OK No Change the fuse

(part 626998)

YesYes

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Error code 11

No energy source is available and

control is on AUTO mode

Please make sure that all energy sources are available

during the trial

No

Yes

Select all the

energies manually

and check which

error codes occur

See the description

of the other error

codes

Replace

Power board

SES version

part 631219

Error code 12

Supply voltage DC is out of range

(9.5V – 15.5V)

If DC mode have been selected manually, the

refrigerator is not switching automatically on another

source of energy when the engine is off

DC input issue

No

Yes

Input supplied at the

fridge is stable and

included between

9.5V and 15.5V

If RV is equipped

with a solar panel.

Disconnect it and

check if the

refrigerator is OK

D+ input issue

No

Yes

Issue with the solar

panel regulator or

solar panel input can

be 100% excluded

Solar panel issue

No

Check if the 5A fuse

is OK

YesYes

No Change the fuse

(part 624030)

Contact Thetford

Yes

Error code 13

Thermistor fails, control

automatically switches to backup

mode (BOS)

Insert thermistor

(part 623077)

No

Check if thermistor

is present

Check if the

thermistor is

plugged in correctly

Check if the wiring

loom is connected to

the power board

correctly

Yes

No Plug in correctly

(5th fin from the right)

Connect correctly

No

Check if the pins in

the wiring loom plug

present and not bent

or loose

Yes

No Fix pins if possible

Yes

Yes

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

No

Broken wiring

harness inside the

fridge issue

Replace the

complete fridge see

the replacement

fridges overview

For the partnumber

of a warranty fridge

When a N180 is

concerned please

replace the fridge

door only

Door number

629724-07

Error code 14

Display board and power board

lost communication to each other

DC input issue

No

YesYes

Input supplied at the

fridge is stable and

included between

9.5V and 15.5V

Check if the 2A

glass fuse is OK No Change the fuse

(part 626998)

YesYes

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Check if the

connections

between the boards

are OK

No Restore the

connections when

not OK replace the

display board

Yes

No

Broken wiring

harness inside the

fridge issue

Replace the

complete fridge see

the replacement

fridges overview

For the partnumber

of a warranty fridge

When a N180 is

concerned please

replace the fridge

door only

Door number

629724-07

Contact Thetford

Yes

Lack of performance

No error code

Do the testing of the fridges on the manual mode

¾On 12 Volts

Check if the input at

the DC HC poles of

the Power Board is

> 13.5V

DC input issue

No

Check if the input at

the heater

connection to the

Power Board is

> 13V

Yes

No

Yes

Check if the heater

impedance is correct

(in Ohm) Replace the DC

heater

(see Spare Parts

List)

Type Min Max

N90-N97-

N98-N100-

N104-N109-

N112-N115

0.93Ω1.13Ω

N145-N150-

N175-N180 0.88Ω1.08Ω

No

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Check if the DC

heater is properly

settled

No Install the DC heater

properly

Yes

Contact Thetford

Yes

Do the testing of the fridges on the manual mode

¾On 230 Volts

Check if the input

between the (+) and

the (-) at the power

board is over 230

Volts

AC input issue

No

Check if the input at

the heater

connection to the

Power Board is

> 215V

Yes

No

Yes

Check if the heater

impedance is correct

(in Ohm) Replace the AC

heater

(see Spare Parts

List)

Type Min Max

N90-N97-

N98-N100-

N104-N109-

N112-N115

312Ω380Ω

N145-N150-

N175-N180 218Ω266Ω

No

Replace

Power board

SES version

part 631219

or

EES version

Part 631220

Check if the AC

heater is properly

settled

No Install the AC heater

properly

Yes

Contact Thetford

Yes

Do the testing of the fridges on the manual mode

¾On Gas

Injector of the burner

is clean. Flame is

dense and blue. Gas

pressure is between

28 and 30 mb

No

Clean the burner.

Replace the burner in

case of bad

combustion

(see Spare Parts

List)

Check if the

thermistor is

properly fitted on the

5th fin from the right

Yes

No Install the thermistor

at the right place

Yes

Check if the flame

diffuser is in the pipe No Install a flame

diffuser

(part nr to be made)

YesYes

Check if the burner

is set properly in

front of the pipe

No Replace the

refrigerator

Issue : A not replaceable fuse (F5) is blowing on the power

boards, caused by wrong signal in circuit (f.i. short cut).

Solution : Re-settable fuse integrated on the power board.

Implementation : November 1st 2007

Spare part nr. : 631219 and 631220

Compensation : 30 minutes

Repair-instruction : See repair instruction part

Power board

on all LCD fridges

Power board old version

Underside of Top Half F5 fuse is at top centre

Modified power board with re-settable fuse shown in position

Issue : Corrosion on all shelves

Solution : Re-inforced coating process to prevent rusting during

life time product (7 years)

Implementation : June 22nd 2007 for all shelves

Spare part nr. : See spare part list

Compensation : 5 minutes

Repair-instruction : not included

Corrosion on all

Fridges shelves

Gas connections

Picture Tool Torque

Nut solenoid GV

Torque spanner 13mm 3 +1/-0 Nm

Burner – orifice adapter

Torque spanner 16mm 7.5 +1/-0 Nm

Gas tube assy – orifice adapter

Torque spanner 14mm 15 +1.5/-0 Nm

Gas tube assy – V85 GV

Torque spanner 11mm 10 +0.5/-0 Nm

Gas inlet tube – V85 GV

Torque spanner 19mm 12 +2/-0 Nm

Thermocouple – V85 Gasvalve

Torque spanner 8mm 1.5 +0.5/-0 Nm

Gas inlet tube - LCD

Torque spanner 17mm 20 +2/ -0