Mars Motors

MARS Motors are replacement electric motors for HVAC/R equipment, sold under the MARS and Amrad brands that RectorSeal now offers after acquiring the former Motors & Armatures product line. The MARS motor lineup covers condenser fan motors, blower motors, and draft inducer motors, along with the capacitors and contactors used to run them, so a motor order typically comes with a matching capacitor decision. Motors are specified by horsepower, voltage, rotation direction, and shaft size rather than by a single universal part number, and a motor that matches horsepower but not rotation direction will run the fan backward. Confirming these four specifications from the original motor's nameplate is what keeps a MARS motor replacement running correctly on the first install.

Subcategories

• Condenser Fan Motors: Condenser fan motors drive the fan on an outdoor condensing unit, pulling air across the coil to reject heat from the refrigerant. These motors are specified by horsepower, rotation direction, RPM, and voltage, and a motor with the correct horsepower but the wrong rotation direction will spin the fan backward and reduce condenser performance. Shaft diameter and length also need to match the original motor, since a fan blade that doesn't seat correctly can create noise or vibration. Recording all four specifications from the failed motor's nameplate is the fastest way to confirm a correct replacement.
• Blower Motors: Blower motors move air through a furnace, air handler, or fan coil, and MARS offers both single-speed PSC motors and multi-speed replacements for systems that cycle between heating and cooling airflow rates. A multi-speed blower motor replacement needs to match not just horsepower but also the number of speed taps wired into the original control board. Rotation direction matters here as well, since a blower running backward will move noticeably less air even at full speed. Confirming speed tap count and rotation before ordering avoids a motor that runs but underperforms.
• Capacitors: Capacitors store and release electrical charge to help start or run a motor, and MARS capacitors are sized in microfarads (MFD) and rated for a specific voltage. Start capacitors work alongside a relay to give a motor extra torque during startup, while run capacitors stay in the circuit continuously to keep a motor running efficiently. Using a capacitor with the wrong MFD rating can cause a motor to run hot or fail to start under load, even if the voltage rating matches. Matching both MFD and voltage to the original capacitor, or to the equipment manufacturer's specification, is necessary before ordering a replacement.
• Contactors: Contactors switch line voltage power to a compressor and condenser fan motor in response to a low-voltage signal from the thermostat or control board. MARS contactors are rated by coil voltage, contact configuration, and amperage, and a contactor with too low an amperage rating for the connected motors can overheat and fail prematurely. Two-pole and single-pole configurations aren't interchangeable on equipment wired for the other type. Confirming coil voltage and amperage rating from the original contactor's label keeps a replacement running within its rated capacity.

Buying Guide

MARS Motors and the related capacitors and contactors sold under the brand are specified by electrical characteristics rather than a single cross-reference number, so a MARS parts order works best when it starts with the nameplate on the failed component. Condenser fan and blower motor replacements need to match horsepower, voltage, rotation direction, and RPM, and getting three of four right still leaves a motor that runs backward or turns at the wrong speed. Blower motor replacements carry an added requirement on multi-speed systems, where the number of speed taps wired into the furnace or air handler's control board has to match the new motor's available speeds. Shaft diameter and length matter on both motor types, since a fan or blower wheel that doesn't seat fully on the shaft can create vibration or noise even when every electrical specification lines up correctly. Capacitors pair closely with the motors they support, and MARS offers both run capacitors, which stay in the circuit continuously, and start capacitors, which work with a relay for extra starting torque; matching microfarad rating and voltage to the original part, or to the equipment manufacturer's specification, prevents a motor from running hot or failing to start. Contactors depend on matching coil voltage and amperage rating to the connected motor load, since an undersized contactor can overheat under normal operation. Across every MARS component category, working from the failed part's own nameplate is more reliable than matching by equipment model alone.

Frequently Asked Questions

What information do I need before ordering a MARS condenser fan motor?

Horsepower, voltage, rotation direction, and RPM from the original motor's nameplate are the specifications that determine a correct replacement. Shaft diameter and length also need to match so the fan blade seats correctly.

Can a single-speed MARS blower motor replace a multi-speed motor?

Not without changes to the control wiring. A multi-speed blower motor is matched to the number of speed taps on the furnace or air handler's control board, and a single-speed replacement won't provide the same range of airflow settings.

What's the difference between a MARS run capacitor and a start capacitor?

A run capacitor stays in the circuit continuously to keep a motor operating efficiently, while a start capacitor works with a relay to provide extra torque only during startup. The two aren't interchangeable, since a start capacitor left in the circuit during normal running can overheat.

Why would a MARS contactor overheat after replacement?

An amperage rating too low for the connected compressor and fan motor load is the most common cause. Matching coil voltage and amperage rating to the original contactor's label avoids this.

Does MARS still sell parts under its own brand name?

MARS and Amrad products are now offered through RectorSeal following its acquisition of the Motors & Armatures product line. The motor, capacitor, and HVAC/R component lineup continues under the MARS name.