The Viair 93940 relay is a compact, 40 A automotive relay designed to isolate a 12 V compressor’s high current from vehicle wiring. It offers moisture-resistant housing, standard spade terminals, and a 30–40 A continuous capacity with brief surge tolerance; install within 12–18 inches of the compressor, use 10–12 AWG power cable, and fuse at the source. Key points: durability, ease of install, protection. Q: Is it enough for heavy-duty compressors? A: Often yes — but check compressor start current.
Key Takeaways
- The Viair 93940 is a 40A 12V relay that safely isolates compressor high current from vehicle dash wiring.
- Four 1/4-inch spade terminals and molded mounting tabs enable secure, simple installation.
- Use 12 AWG power and 16 AWG trigger wires, with an inline fuse within 18 inches of the battery.
- Moisture-resistant case and recommended dielectric grease improve durability and corrosion protection.
- Proper mounting within 6–12 inches of the compressor and quality crimped terminals ensure reliable performance.
Why the Viair 93940 Relay Matters for 12V Compressors
Because a dedicated relay isolates the compressor’s high current draw from the vehicle’s dash wiring, the Viair 93940 matters for 12V compressors: it protects circuits, guarantees reliable starts, and extends component life.
This benefits overview explains relay functionality and practical value.
What does it do? It handles up to 40A, routes power through four 1/4″ spade connectors, and mounts via molded tabs.
Who needs it? Any 12V compressor that draws significant current.
Installation note: each compressor requires its own relay. Consider moisture-resistant housing, secure connections, and matching amperage to avoid overheating or premature failure.
Key Features and Specifications
When evaluating the Viair 93940, readers should focus on a concise set of measurable features that determine compatibility and longevity: a 40 amp capacity for 12-volt systems, four 1/4-inch spade post connectors for secure wiring, molded mounting tabs and a moisture-resistant case for durable installation, and a maximum ampere draw rating of 40 A to match against compressor specifications.
- 40 Amp capacity, designed for 12 V compressors
- Four 1/4″ spade connectors for reliable connections
- Molded mounting tabs and moisture-resistant case
- Max ampere draw: 40 A, matches compressor demands
How does relay functionality affect performance? It enables controlled switching, improves electrical safety.
Installation Tips and Durability Notes
After reviewing the Viair 93940’s specifications—40 A capacity, four 1/4‑inch spade connectors, molded mounting tabs, and a moisture‑resistant case—the reader can move on to practical installation guidance and durability notes that affect long‑term performance.
Advice: use proper wiring techniques, 12 AWG for power, 16 AWG for trigger, fuse at battery within 18 inches, crimped and heat‑shrunk terminals.
Relay placement: mount within 6–12 inches of compressor, avoid direct heat, secure to chassis with supplied tab.
Q: How to protect it?
A: Seal connectors, use dielectric grease.
Expect durable service if mounted correctly and kept dry.
Frequently Asked Questions
Does It Come With a Wiring Harness or Only the Relay Unit?
Only the relay unit is included. 40 amps highlights its capacity. He notes wiring options require separate purchase; installation tips advise one relay per compressor, secure 1/4-inch spade connections, and use mounting tabs for stability.
Is the Relay Compatible With 24V Systems?
No; it is not compatible with 24v systems. The relay specifications specify a 12 Volt, 40 Amp design. For compressor compatibility, users should select a relay rated for 24V and matching amperage for safe operation.
What Is the Warranty Period for the Viair 93940 Relay?
The warranty period is one year, enough to reassure like a fortress guarding warranty coverage and product lifespan expectations. It protects against defects for twelve months, offering limited remedies if failures occur within that time.
Can This Relay Be Used With Multiple Compressors Simultaneously?
No; the relay cannot support multiple compressors simultaneously. Its 40 amp relay capacity limits use to a single compressor per relay, so each compressor in a compressor setup requires its own dedicated relay for safe operation.
Are Replacement Spade Connectors Included With the Relay?
“Don’t count your chickens before they hatch.” He states: replacement spade connectors are not included; connector types are four 1/4 inch spade posts. Installation tips: bring appropriate crimp or solder connectors and secure mounting tabs.
