Isotherm · Refrigeration

Isotherm fridges and cooling units

Isotherm is the marine refrigeration brand of Indel Marine in Novafeltria, Italy, part of the Indel B group; for years the company traded as Indel Webasto Marine, and its old website now forwards to indelb.com. The range covers built-in Cruise fridges and freezers (Classic, Elegance in silver or black, stainless Inox and Inox Clean Touch, Drink versions without freezer compartment, F freezers and combis), Drawer units, and cooling units for boxes you build yourself: the air-cooled Compact Classic, the self-pumping SP with its condenser in the galley-sink through-hull and the pump-cooled Magnum, with a mechanical thermostat or with ASU, SEC or ITC control. From the late 1990s almost every unit runs on a Secop (ex-Danfoss) BD35F or BD50F compressor with the same 12/24 V electronic unit, Isotherm SEG00002DA (Secop 101N0210, today 101N0212), so compressor-side parts and fault codes are shared across the range and with other BD-based fridges. Newer models break that pattern: the CR 42 Elegance has a Secop BD Micro, Drawer 42 and 85 use BD Micro and BDN45F Nano, and the 2026 catalogue lists most Cruise models with an IB35C compressor, so read the data plate before you order electronics, a compressor or a thermostat.

Manuals & documents

Isotherm’s current downloads at Indel B need a login, and the old indelwebastomarine.com, where manuals and spare-parts lists were public, is gone. The links therefore lead to the current catalogue, to Isotherm manuals and catalogues hosted by the US dealer Defender, to archived copies of the former Isotherm download area on archive.org, and to Secop for the compressor electronics. We host no manuals.

Wear parts & part numbers

PartOEM numberAlso fitsNote
Control unitSEG00002DA · 101N02121,2,3,4,5replaces 101N0210—Standard 12/24 V electronic unit for every BD35F or BD50F: Cruise CR 49 to 200 (Classic, Elegance, Inox, Clean Touch), Drawer 49/65, Compact, SP and Magnum BD50F units. Isotherm’s parts lists name it Secop 101N0210 under the same SEG number, the catalogue and later lists Secop 101N0212; Fisheries Supply calls it a direct replacement for the 101N0210 on all Isotherm units since 1998 (also sold as Frigoboat E50896). Before buying, bridge T and C: if the compressor then runs, the thermostat is at fault, not this unit.
Control unitSEG00030GA · 101N05101,2,6,7,8—AC/DC electronic unit for BD35F/BD50F: runs on 12/24 V DC or 100–240 V AC, prefers AC when both are present. Optional on Cruise fridges and cooling units in place of the SEG00002DA; Cruise models fitted with it are about 19 mm deeper. Technofluid lists the same Isotherm number as Secop 101N0511.
Control unitSEG00043DA · SEG00050GA9—Electronic units for the Secop BD Micro compressor of the CR 42 Elegance: SEG00043DA for 12/24 V, SEG00050GA AC/DC. They do not fit a BD35F; older CR 42s with a BD35F take the SEG00002DA. Numbers from Isotherm’s CR 42 Elegance parts list only.
ThermostatSEA00092DA3,9,10,11—Mechanical thermostat of the current Cruise CR 42, 49, 65, 85 and 130 (Classic, Elegance, Clean Touch); knob SEA00093AA, housing SEA00094AA. Older Cruise and Drawer models take the SEA00031DA below.
ThermostatSEA00031DA12,13—Thermostat of the earlier Cruise CR 36, 49, 50, 65, 100 and 120, the CR 85 and 130 built until 2008, and Drawer 49, 65, 85 and 130.
FanSBG00005BA3,14,2,5—12 V low-speed condenser fan ‘for Compact and Cruise’: Cruise CR 85 and 130 (Classic, Elegance, Clean Touch), Drawer 65 and the air-cooled cooling units. A 12 V fan is used on 24 V systems too, and the controller’s fan output allows about 0.5 A.
FanSBG00037DA10,9—9 × 9 cm condenser fan of the smaller Cruise Elegance, CR 42, 49 and 65.
CompressorSBA00002DA3,2,12,15—Secop BD35F 12/24 V without electronic unit, as used in Cruise CR 49 to 130, Drawer 65 and the BD35F cooling units. Changing it means opening the refrigerant circuit, so it is a job for a refrigeration technician; the current Secop code of the BD35F is 101Z0200.
CompressorSBA00045DA9—Secop BD Micro 12/24 V without electronic unit, CR 42 Elegance (with the SEG00043DA or SEG00050GA electronics). Same caveat as above: refrigerant work.
CondenserSBD00122AA · SBD00104AA3,14,10—Cruise condensers: SBD00122AA condenser kit for CR 85 and 130 (Classic, Elegance, Clean Touch); SBD00104AA for CR 42, 49 and 65 Elegance. Refrigerant work.
EvaporatorSBF00105AA · SBF00109AA · SBF00118AA3,10,9—Cruise evaporators: SBF00105AA for CR 85 and 130, SBF00109AA for CR 49 and 65 Elegance, SBF00118AA for CR 42 Classic and Elegance. Refrigerant work.
Filter drierSBD00026AA · SBD00020AA2,16,10—SBD00026AA: 10 g filter drier, Ø 19 mm, for Cruise fridges and the air-cooled and SP cooling units; SBD00020AA: 40 g filter drier for the Magnum. Renewed whenever the circuit is opened.
Freezer compartment doorSGC00294AA3,9,17,18—Freezer compartment door of the Cruise Elegance CR 42, 49, 65, 85 and 130 (also on the 2018 CR 130 Clean Touch); it hooks on with tabs at the top, no clips, 8½ × 4⅝ in. Not for the Freeline 115 Elegance; for older Classic Cruise fridges Fisheries Supply names SGC00131AA (one source).
Freezer compartment doorSGC00005AA · SGC00004AA · SGC00003AA1,19—Doors for the O-shaped evaporators of the cooling units: SGC00005AA small, SGC00004AA medium, SGC00003AA big.
Hinge setSBE00194AB · SBE00195AB3,17—Upper (SBE00194AB) and lower (SBE00195AB) door hinge of the Cruise Elegance, also on the 2018 Cruise 130 Clean Touch.
LatchSGD00043AA3,9,17,20—Bright-silver handle kit with springs and pivot for the Cruise Elegance (CR 42, 49, 65, 85, 130); the 2018 Cruise 130 Clean Touch list uses it too.
LatchSGD00012AA20,12—Stainless door latch for the earlier Cruise Inox and the Drawer models; not for Elegance. On some early doors (2004–2005) the latch is not screwed on, and then the whole door has to be replaced.
FuseSEB00039AA10,8—15 A fuse kit from the Cruise Elegance parts lists; use 7.5 A on 24 V.
AC power packSEH00017HA · SEH00018HA · SEH00019HA · SEH00020HA1,16,21,22—Isotherm Power Pack 100–240 V AC for BD35F/BD50F units: SEH00017HA EU plug, SEH00018HA US, SEH00019HA AU, SEH00020HA UK. It sits between shore power and the DC electronic unit and feeds 24 V DC, switching back to the battery when shore power goes. Older catalogues and the Magnum parts list show the earlier SEH00004HA; BD80F units need SED00035GA (230 V) or SED00035PA (115 V); not for the Magnum Twin.
Speed controllerSED00033AA23,1—Smart Energy Control kit: processor module that plugs onto the Secop electronic unit (101N0210 family), air sensor and potentiometer; it varies compressor speed and stores cold in the food when the engine or shore power is on. Cruise Elegance cabinets are prepared for it; it suits any fridge or freezer with BD35F/BD50F and a visible evaporator. 12/24 V DC only.
ThermostatSEA00048DB1,24—High-speed thermostat kit for running a cooling unit as a freezer (current catalogue); the 2014 US catalogue lists a kit with the same description as SEA00076DA.
Condenser anode (sea-water cooled)SBE00006AA · SBE00008AA1,2,16,25—SBE00006AA: zinc for the SP through-hull condenser, fixed to its outer face with two screws. SBE00008AA: 3/8 in zinc for the Magnum’s copper-nickel condenser, to be checked at least once a year.
CondenserSBD00066AA2,1—Complete SP condenser (through-hull) with 1.2 m pipes and couplings, standard version. The skin-fitting valve kit for SP units is SFD00008AA.
Raw water pumpSBB00003DA16—Sea-water pump of the Magnum. Its speed is set by the voltage reducer SED00019DA with thermistor SEB00027AA on the condenser (copper-nickel condenser SBD00016AB).
Mounting bracketSGE00012AA1,2,26—‘Click-on’ bracket for the compressor of the air-cooled and SP cooling units, for wall or floor; not on Magnum units, and AC/DC versions use the black bracket SBE00178AA. Older Compact manuals print SGE00002AA.

Numbers checked against the sources below on 23 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

TaskInterval
Condenser cleaningAt least once a year, in practice every season: with the power off, brush and vacuum the dust off the condenser and fan behind the fridge or on the cooling unit, using a soft brush and no sharp tools8,27,28
DefrostingWhen the frost on the evaporator is about 3 mm thick (Cruise: 1/8 in; Compact: 3–4 mm; Magnum: 4–5 mm): switch off, leave the door open, never chip the ice off with metal, and restart only when the box is dry. Frost-free models need no manual defrosting8,28,22,1
GasketsNo fixed interval: if the compressor runs long without cooling enough, check the door position and seal and clean the condenser; during lay-up keep the door in its vent position so the seal does not stick and the cabinet stays dry8,27
AnodeMagnum: check the zinc in the water circuit at least once a year and replace it when worn; take it out while the system stands dry22
Strainer cleanMagnum: clean the water filter at short intervals, since dirt cuts water flow and cooling capacity22
Storage / winterisingFridge and cooling unit stay aboard over winter. Defrost fully, dry the cabinet and drip tray, set the door to its vent position and take out the bulb or cut the power. Below about 0 °C the compressor will not start. Magnum: run it on fresh water to flush, then drain the water circuit and pump or fill them with antifreeze27,8,22

From Isotherm’s manuals for Cruise fridges, Compact and Magnum cooling units. The refrigerant circuit is sealed and needs neither maintenance nor topping up; Isotherm sets no hour-based intervals.

Specifications

VersionsBuilt-in fridges: Cruise (Classic, Classic Total Black, Classic White, Elegance silver or black, Inox, Inox Clean Touch; Drink without freezer compartment, F = freezer, combis with two doors) and Drawer units · cooling units for your own box: Compact Classic (air-cooled), SP (self-pumping, sea-water cooled), Magnum (sea water by pump), each with mechanical thermostat or with ASU (holding plate), SEC (Smart Energy Control) or ITC/ITC+ (digital display) · 2026: Slim-Fit unit with concentric evaporator1,19
ModelsCruise from 36 to 320 l gross; the core sizes CR 42, 49, 65, 85 and 130 (plus CR 100, Drink 130/160, freezers CR 63 F, 65 F, 90 F) share most parts; large models CR 195 and 200 (two doors), in North America also CR 165, 187, 190, 219 and 271 · Drawer from 16 to 190 l · cooling units for boxes of 60–600 l as fridge or 20–200 l as freezer1,19
CompressorSecop (ex-Danfoss) BD35F in Cruise 36 to 130, Drink 130, the F freezers and Drawer 49/65; BD50F in the large fridges (CR 160 Drink, 165, 187, 190, 200, 219, 226, 271); two BD35F in the CR 195; cooling units BD35F, BD50F or BD80F. Exceptions: CR 42 Elegance with Secop BD Micro, Drawer 42 BD Micro, Drawer 85 BDN45F Nano, Drawer 65 Frost-free BD1.4F VSD, and in the 2026 catalogue most Cruise Classic, Elegance and Inox Clean Touch with an IB35C. Current Secop codes: BD35F 101Z0200, BD50F 101Z122019,1,9,15,29
RefrigerantR134a; the charge is on the data plate (inside the cabinet on Cruise fridges, on top of the compressor on cooling units). The circuit is sealed and is never topped up; cooling units come pre-charged with self-sealing quick couplings, and the 2 m connecting pipe cannot be shortened. The 2026 Slim-Fit uses R1234yf8,28,22,1
Voltage12 or 24 V DC with the same electronics; optional AC/DC unit for 100–240 V AC 50/60 Hz (AC is preferred when both are present, back to DC after a 1-minute delay). Battery protection measured at the electronic unit: cut-out 9.6 V (21.3 V), cut-in 10.9 V (22.7 V); with the C–P jumper cut, 10.4/11.7 V (22.8/24.2 V). ASU units: 10.0/12.0 V (22.0/23.5 V)8,5
Current drawRunning at 12 V (Cruise, US manual): CR 42/49/65 2.5–2.7 A, CR 85 3.8–4 A, CR 130 4.7–5 A, CR 130 Drink 5–5.3 A, half at 24 V. The later Cruise manual gives peak values of 5 A (CR 42–65), 7 A (CR 85, 100), 8 A (CR 130 and freezers), 12 A (CR 200) and 15 A (CR 195). Drawer 49/65 5 A. Compact units BD35F 6 A, BD50F 7 A, BD80F 10 A8,27,30,28
Power consumptionAverage in Wh per 24 h (+5 °C inside, 25 °C ambient, later Cruise manual): CR 42/49 340, CR 65 360, CR 85 380, CR 100/130 400, CR 200 800, CR 195 840. 2026 catalogue, Elegance: CR 42 285, CR 49 265, CR 65 275, CR 85 368, CR 115 257, CR 130 418. US manual average at 12 V: CR 42/49 0.6 A, CR 65 0.7 A, CR 85 0.8 A, CR 130 1.2 A; Drawer 49 0.8 A, Drawer 65 0.9 A27,1,8,30
Breaker / fuseFuse in the plus cable close to the battery: 15 A at 12 V, 7.5 A at 24 V for Cruise 36 to 130, Drawer 49/65 and BD35F/BD50F cooling units; CR 200 20/10 A, CR 195 25/12.5 A, Magnum Twin 20/10 A, BD80F 30/15 A. Main switch at least 20 A (Secop); AC supply fused at 4 A27,22,28,5
Power cable sizeStraight to the battery or main switch, never through the boat’s switch panel. Maximum length battery to electronic unit, 12 V / 24 V: 2.5 mm² 2.5/5 m, 4 mm² 4/8 m, 6 mm² 6/12 m, 10 mm² 10/20 m (US manual: AWG 12 13 ft, AWG 10 20 ft, AWG 8 33 ft at 12 V)23,5,8
Fault codesSecop electronic unit: a 10 mA LED between + and D flashes the code, each flash ¼ s, repeated every 4 s: 1 battery protection (voltage outside the cut-out range) · 2 too many start attempts or fan current above 0.5 A · 3 compressor cannot start (rotor blocked or pressure difference above 5 bar) · 4 speed below about 1850 rpm (system overloaded) · 5 electronics too hot (poor ventilation, high ambient) · 6 NTC thermostat short-circuited or disconnected. ASU panel: green plus flashing yellow and red = electronic unit error, new attempt after 1 minute; flashing yellow = low-voltage cut-out. Inox Clean Touch and ITC displays show the codes themselves28,5,8,1
Speed settingsWith a mechanical thermostat and no resistor the compressor runs at a fixed 2000 rpm; a resistor in the thermostat circuit sets 2500 rpm (277 Ω), 3000 rpm (692 Ω) or 3500 rpm (1523 Ω). Isotherm units with larger evaporators have this resistor fitted at the T terminal for medium or full speed; SEC and ITC vary the speed themselves5,22,1
Box sizeCooling units are rated by box volume, which the item code shows (U125X041… = 125 l fridge or 41 l freezer). As a freezer a unit cools about a third of its fridge volume; for the tropics reduce the box by 10–20 %. Insulation: 30 mm for 50 l, 50 mm up to 80 l, 100 mm or more for larger boxes, three times as thick for freezers1,19,22
EvaporatorsO-shaped (small, medium, big; with freezer compartment and evaporator door), L-shaped and flat plates that can be bent once or twice (Magnum: up to three times), holding plates for ASU and ITC+. Pre-charged pipe of 2 m through a Ø 30 mm hole; coil the excess, never cut it; extensions with couplings 1, 2 and 3 m (SBD00031XA, SBD00154XA, SBD00155XA). Mount the evaporator as high as possible and clip the thermostat sensor at least 70 mm onto it26,22,1
CoolingAir-cooled: a fan on the condenser; cool air must enter from below and warm air leave at the top, never from an engine room (a Cruise needs about 15–23 sq in, 100–150 cm², of free opening below and behind; ventilation hose kit SBE00004AA). SP: no fan or pump; a spiral condenser inside a special through-hull that replaces the galley-sink drain fitting (G 1¼ in, Ø 42 mm, or G 2 in, Ø 60 mm), supplied with zinc and seacock, for sea water up to 28 °C. Magnum: built-in self-priming pump through a copper-nickel condenser with zinc; a voltage reducer runs the pump faster as the condenser warms; the unit may sit up to 2 m above the waterline8,19,1,22
DimensionsCruise Elegance, W × H × D in mm without the 50 mm door: CR 42 380 × 525 × 455, CR 49 380 × 525 × 452, CR 65 450 × 530 × 473, CR 85 475 × 627 × 505, CR 115 525 × 797 × 495, CR 130 525 × 750 × 510. Models with the AC/DC electronic unit are ¾ in (about 19 mm) deeper. Older Classic and Inox cabinets differ by a few millimetres, so check the cut-out drawing of your version1,8
WeightCruise Elegance: CR 42 14 kg, CR 49 17 kg, CR 65 18 kg, CR 85 22 kg, CR 130 27 kg, CR 115 29 kg; CR 200 Classic 48 kg. Cooling units: air-cooled Compact 8–9 kg, SP 10–11 kg, Magnum 11–12 kg1
MountingCompressor upright. Remote compressor: CR 42 up to about 1.5 m on its own bracket in older models (2026: 1 m), CR 36 1.2 m, Drawer 70 1.1 m, Drawer 105 1.5 m. Cruise fridges sit on their rubber feet and are held by the flange or mounting rails, or by at least two fixing points. Cooling units: click-on bracket for wall or floor (not on Magnum or AC/DC units); Magnum on a rubber-mounted plate with four (Twin: six) holes27,1,8,22
Max. installation angleCooling units run continuously at 30° of heel; Cruise fridges at 30° and briefly more. If tilted too far the compressor stops and restarts once the boat is upright again26,27
Operating temperatureCruise: ambient 0–45 °C (32–113 °F); near or below 0 °C the compressor will not start. Compact units up to 45 °C. The Secop standard electronics are rated to 43 °C ambient, the AC/DC unit to 55 °C8,27,26,5,7

Good to know

  • Find the faulty part before you buy one: bridge T and C on the electronic unit. If the compressor starts, the thermostat is faulty; if not, the electronic unit or compressor is. Short start attempts with clicks usually mean the voltage collapses at start: the manual wants at least 11 V at the unit while it starts, so check fuse holder, terminals and cable size first, then read the LED code.8,4,28
  • Read the data plate before ordering. The same model name has changed inside: a CR 42 came with a BD35F, later with a Secop BD Micro and its own electronics, and the 2026 Cruise models use an IB35C. Thermostat, freezer door and latch also differ between Classic, Inox and Elegance (SEA00031DA or SEA00092DA, SGC00294AA only for Elegance, SGD00012AA not for Elegance).8,9,1,20,18
  • Most ‘weak’ Isotherm fridges are short of air. Cool air has to come in low and leave high behind the cabinet; a fridge built tight into furniture or fed with engine-room air runs long, uses more power and may trip on error code 5. Add vent openings with grilles, clean the condenser and fan, and only then suspect the refrigerant charge.8,27,5
  • Quick couplings: connect the thin capillary line first, turn only the female nut and hold the male half still, or the capillary breaks; screw home and tighten with 21 and 24 mm spanners. Keep the caps: the couplings can be reopened without losing gas. The pre-charged pipe must never be shortened.26,22
  • Isotherm’s Cruise parts lists carry the door only as a complete assembly (for example SGC00369AA for the CR 130 Elegance) and show no separate door seal. If warm air gets in, check the door position, hinges and latch first; in lay-up the Elegance door has a vent stop that keeps it ajar.3,27
  • Listings found through ‘BD35F’ or ‘BD50F’ may come from other fridges built on the same Secop compressor, such as Frigoboat systems. The compressor and the Secop electronic unit are the same parts; Isotherm’s evaporators, thermostats and doors are not.5,4

Videos & how-tos

Links to YouTube, nothing embedded. The maker’s own channel comes first; the rest are channels we found clear and correct for this model.

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Sources

  1. indelb.com/app/uploads/2025/12/catalogo_indel_marine_2026_web-2.pdf
  2. web.archive.org/web/20211208002516/https://www.indelwebastomarine.com/fileadmin/webasto__…
  3. web.archive.org/web/20211130232938/https://www.indelwebastomarine.com/fileadmin/webasto__…
  4. fisheriessupply.com/isotherm-module-for-secop-danfoss-bd35-and-bd50-compressors/seg00002da
  5. secop.com/fileadmin/user_upload/technical-literature/electronic-units-instructions/eol/bd…
  6. fisheriessupply.com/isotherm-ac-dc-module-for-all-secop-danfoss-bd35-and-bd50-compressors…
  7. secop.com/fileadmin/user_upload/technical-literature/electronic-units-instructions/eol/bd…
  8. defender.ca/assets/pdf/isotherm/cruise42-130_install_operate.pdf
  9. web.archive.org/web/20211208005515/https://www.indelwebastomarine.com/fileadmin/webasto__…
  10. web.archive.org/web/20211207234347/https://www.indelwebastomarine.com/fileadmin/webasto__…
  11. technofluid.it/en/product/cruise-thermostat-42496585130-c-code-sea00092da-isotherm/
  12. web.archive.org/web/20211208010308/https://www.indelwebastomarine.com/fileadmin/webasto__…
  13. technofluid.it/en/product/thermostat-cr36495065100120dr130dr85bi13585130-until-2008-code-…
  14. web.archive.org/web/20211208002752/https://www.indelwebastomarine.com/fileadmin/webasto__…
  15. secop.com/fileadmin/user_upload/SEPS/datasheets/en/bd35f_101z0200_r134a_12-24vdc_09-2024_…
  16. web.archive.org/web/20210616150216/https://www.indelwebastomarine.com/fileadmin/webasto__…
  17. web.archive.org/web/20211201001342/https://www.indelwebastomarine.com/fileadmin/webasto__…
  18. fisheriessupply.com/isotherm-freezer-door-for-elegance-models/sgc00294aa
  19. defender.ca/assets/pdf/isotherm/inde_usa_catalog.pdf
  20. fisheriessupply.com/isotherm-door-latch/sgd00012aa
  21. fisheriessupply.com/isotherm-ac-to-dc-power-converter/seh00004hb
  22. defender.ca/assets/pdf/isotherm/2513-magnum-install-operating-manual.pdf
  23. web.archive.org/web/20160417234313/http://www.indelwebastomarine.com:80/fileadmin/webasto…
  24. defender.com/assets/pdf/isotherm/indel_catalog_10_14.pdf
  25. fisheriessupply.com/isotherm-electric-engine-water-heater-zinc-anode/sbe00006aa
  26. web.archive.org/web/20120425070530/http://www.indelwebastomarine.com:80/Download_area/gra…
  27. web.archive.org/web/20160417234248/http://www.indelwebastomarine.com:80/fileadmin/webasto…
  28. web.archive.org/web/20160813075529/http://www.indelwebastomarine.com/fileadmin/webasto_fi…
  29. secop.com/fileadmin/user_upload/SEPS/datasheets/en/bd50f_101z1220_r134a_12-24vdc_09-2024_…
  30. defender.com/assets/pdf/isotherm/drawer49_drawer65.pdf

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