The Dometic Fan-Tastic Vent 1250 is a manually opened 12-volt roof fan with three fan speeds and reversible airflow. Its factory wiring schematic shows the fan motor, three-speed selector, reversing switch, 4-amp fuse and lid-position switch. Use the labelled circuit drawing below to identify the original connections before selecting a replacement component.
Original Fan-Tastic Vent 1250 wiring schematic
This model-specific Dometic drawing labels the front hinge side, fan motor, manual lid knob, reversing switch and three-speed selector. Wire callouts 1a–1d and 2a–2c correspond to the 12-volt colour key below. The original schematic is marked November 2013; compare it with the actual installed vent and model label before working on an earlier or revised assembly.
On a phone, use the PDF link to enlarge the wire colours and terminal positions.
Model 1250 wire and switch identification
| Callout | Wire | Factory connection |
|---|---|---|
| 1a | 16 AWG black | 12V positive supply to the 4A slow-blow fuse |
| 1b | 16 AWG black | 4A fuse to the three-speed switch B terminal |
| 1c | 16 AWG black | Three-speed switch M terminal to reverse switch, 5 o’clock position |
| 1d | 16 AWG red | Reverse switch, 3 o’clock position, to fan-motor positive |
| 2a | 16 AWG white | Supply ground to reverse switch, 7 o’clock position |
| 2b | 16 AWG white | Reverse switch, 9 o’clock position, to the lid-position switch in the fan base |
| 2c | 16 AWG white | Lid-position switch to fan-motor ground |
The motor direction is selected with the IN/OFF/OUT reversing switch, while the separate three-speed switch controls the airflow setting. The lid-position switch is in the motor's ground circuit. If the fan stops operating, check the lid position, fuse, supply and existing switch connections rather than assuming the fan motor has failed.
Relevant Fan-Tastic replacement parts
Fan-Tastic 1250 assemblies have appeared in different lid and base configurations. Match the installed manufacturer number, blade hub, dome profile and manual-lift hardware before choosing a service component.
K1137-00 · Replacement fan blade11½-inch clear blade; selected Fan-Tastic 1250 parts references specify this number. Match the 8 mm hub and original fan shaft.View K1137-00 fan blade
K1020-19 · Standard smoke domeShown in selected 1250 smoke-dome parts lists. Verify hinge type, original lid dimensions and configuration; flat and insulated domes are different.View K1020-19 dome lid
K1031-05 · Three-speed fan switchA replacement speed selector for compatible Fan-Tastic vents. Compare the original stamped number and B/M terminals.View K1031-05 on NewRVParts
K1122-05 · Dome-position switchPlunger-style switch in the lid circuit. Check the mounting and connector arrangement on your original unit.View K1122-05 on NewRVParts
K901809 · Fuse-holder assemblySnap-in holder with cap and fuse. Confirm the replacement fuse is the specified 4A slow-blow type.View K901809 on NewRVParts
K1140-09 · Manual lid knobManual dome lift knob and screw for selected Fan-Tastic configurations. Not the fan-speed knob.View K1140-09 on NewRVParts
The manual lift knob, fan-speed control, airflow reversing switch, lid-position switch and complete motor assembly may also need service. Their replacement numbers can vary by the exact 1250 assembly. Read the original component number before ordering; do not substitute a 3350 lift motor or 7350 remote-control component.
Confirm model and revision before electrical service
Check the identification label on the vent body and the existing switch terminals. The manufacturer schematic identifies the connection positions by clock orientation, which is important if replacing a switch with a different physical terminal layout. This reference is for the 1250 manual-lift electrical arrangement, not the powered-lid 3350 or remote-equipped 7350 circuits.
Compare the 3350 powered-lid wiring guide or the 7350 remote and automatic-lift guide. For vent lids, screens and ceiling trim, see the Fan-Tastic Vent service-parts reference, or browse the Fan-Tastic parts diagrams by model.