Overview
Electronic contactors are now replacing traditional magnetic contactors in Carrier® Supra® and Oasis® truck refrigeration units. This update improves system reliability, simplifies installation, and reduces the number of wiring components required.
The new electronic contactors remove auxiliary wiring used in previous magnetic contactor designs and introduce polarity-sensitive connections that must be wired correctly during installation or replacement.
Technicians servicing these systems should ensure the correct contactor version is installed and that polarity requirements are followed to avoid system faults.
Key Enhancements
The new electronic contactors introduce several improvements over the previous magnetic versions:
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Higher reliability, reducing failures caused by mechanical wear
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Simplified installation, with fewer wiring connections required
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No auxiliary black wires required, simplifying service work
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Polarity-sensitive wiring, ensuring consistent electrical operation
These updates help improve the durability and serviceability of truck refrigeration systems.
Affected Refrigeration Units
The electronic contactor update applies to the following truck refrigeration systems.
| Truck Unit Model | Serial Number From |
|---|---|
| Supra® & Oasis® Single Temperature | TC807113 (Rev A) |
| Supra® MT | GC802074 |
| Supra® U Single Temperature | TC749062 |
| Supra® U Multi Temperature | GC802074 |
Units produced before these serial numbers used magnetic contactors. Newer units use electronic contactors as the standard configuration.
Key Installation Differences
Electronic contactors operate differently from traditional magnetic contactors.
Magnetic contactors (previous design)
Older magnetic contactors allowed positive and ground connections to be wired in either orientation.
Electronic contactors (new design)
The new electronic versions are polarity-sensitive, meaning the positive and ground connections must be wired according to the markings on the contactor.
Incorrect wiring may prevent the contactor from operating correctly and can cause system failure.
Contactor Replacement
| Previous Contactor | Old Magnetic Contactor P/N | New Electronic Contactor P/N |
|---|---|---|
| Before serial number change | 10-00433-00 (Auxiliary Right) | 10-00503-31 (Auxiliary Right) |
| After serial number change | 10-00503-31 | 10-00503-31 |
Older magnetic contactors are no longer used in newer models.
When replacing a contactor in an older unit, the electronic version should be installed as the replacement component.
Polarity Requirements
Electronic contactors must be wired with the correct polarity.
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+12V must be connected to the positive terminal
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Ground must be connected to the ground terminal
Incorrect polarity may prevent the contactor from operating correctly.
Polarity reference for the C30 electronic contactor used in Carrier® Supra® and Oasis® truck refrigeration units
The diagram illustrates the correct polarity connection for the electronic contactor within the electrical system.
Technicians should always confirm wiring polarity before powering the system.
Download the Full Technical Bulletin
For complete technical information and wiring diagrams, download the original bulletin.
Download PDF Technical Bulletin
Truck Range Electronic Contactor Update
Need Assistance?
If you require help identifying compatible replacement contactors or verifying installation requirements for truck refrigeration units, the Myriad technical team can assist.
Visit www.myriadparts.com or contact our team for support.