Yes, that is the most likely reason the AC installer did not connect the power because of the aluminum wiring. Here's a breakdown of why and what could be happening: Aluminum Wire Concerns

Aluminum wiring, especially older types, has a higher risk of:

Oxidation

Aluminum oxidizes quickly when exposed to air, creating a non-conductive layer. This increases resistance at connections.

Expansion and Contraction

Aluminum expands and contracts more than copper with temperature changes. This can loosen connections over time, leading to arcing and fire hazards.

Creep

Aluminum is more prone to "creep," which is a gradual deformation under pressure. This can also loosen connections.

Termination Compatibility



Copper-Only Terminals

Many older or lower-quality electrical components are only rated for use with copper wire. Using aluminum wire with these terminals is extremely dangerous.

Corrosion

When aluminum and copper are directly connected without the proper materials, galvanic corrosion can occur, which degrades the connection.

Why the AC Installer Stopped



Safety and Liability

A reputable AC installer would recognize the dangers of connecting aluminum wiring to incompatible terminals. They wouldn't want to be liable for potential fire hazards or electrical issues.

Code Compliance

Electrical codes often have specific requirements for terminating aluminum wiring. A proper installation involves using connectors and methods that are specifically designed and rated for aluminum.

Solutions and Recommendations



Copper Pigtailing

The most common method is to use a special connector (like a COPALUM connector or an antioxidant paste with a wire nut rated for aluminum-to-copper connections) to create a short "pigtail" of copper wire that can then be safely connected to the AC unit's terminals. This must be done by a qualified electrician.

Replacing the Aluminum Wire

If the aluminum wire run is relatively short, it might be cost-effective to replace the entire run with copper wire.

Aluminum-Rated Terminals

In some cases, the AC unit's terminals might be replaceable with terminals that are specifically rated for use with aluminum wire. Check the unit's documentation.

Important: The customer should hire a qualified and licensed electrician to properly address the aluminum wiring issue. This is not a DIY project. A properly qualified electrician will assess the specific situation, determine the best solution, and ensure the connection is safe and code-compliant. Flag for review