Bryant logo: white gear and power symbol on dark gray with red Bryant banner.

This symbol is for an equipment ground- almost any time you see three lines parallel either horizontally or vertically- they will mean earth/ ground.



Here is an Outdoor Fan Motor where you can see it contains two windings, Start and Run. Also, in green is another symbol for ground

Pulled from an indoor ceiling cassette 40MBCQ

The chart/table on outdoor units have loads more of information so I will assist in clarifying.

These units are more complex and have more variables to consider.


*to keep things simple, we typically round close decimal numbers*


Min. Piping Length per each indoor unit- This is the minimum allowed amount of lineset for each indoor unit


Standard Piping Length per each indoor unit- this is the amount of lineset that has been “reserved” for each indoor unit for refrigerant charge purposes.


Max. outdoor-indoor height difference- how far you can separate the indoor from the outdoor vertically. Two labels are shown- IU indoor unit above OU outdoor unit and vice versa.


Max. height different between indoor units- if the indoor units are on different levels, then they should not exceed this amount of vertical separation amongst themselves.


Max. Length per each indoor unit- no indoor unit should have a lineset longer than this number. Do not exceed this number for any indoor unit lineset.


Max. Piping Length with no additional refrigerant charge- add together all of the lineset lengths for all the indoor units. If your lengths are above this number, then additional charge is needed.


Total Maximum Piping Length per system– when adding together all the indoor pipe lengths, this is the total length that the unit can support. Pipe lengths greater than this are not approved nor recommended.


Additional refrigerant charge- if your total lineset length is over the “Max. Piping Length with no additional refrigerant charge” amount, this is how many ounces per foot should be added to the unit for proper operation.


Pipe sizes: these show the pipe sizes with an asterisk (*) and then the quantity of those ports.

For example: from the 36K– 1/2 *2+3/8*2

This means 2 at ½ and 2 at 3/8.


In the event that the correct line set size is ran and it is not the same size as the hookup of this unit, use the factory supplied adapters to make the connections.

Steven Simmons

Technical Services Manager Southwest District

October 14, 2021

Where Does the Orange Wire Go On a Carrier Commercial Heat Pump?

Model numbers that this document pertains to: 38AUQ/40RUQ, 50FCQ, 50GCQ, 50HCQ, 50KCQ, 50TCQ


No matter how long you have been in the business, when you come across your first Carrier lite commercial heat pump system it is going to throw your thought process for a loop! You will notice that the unit is a heat pump but there is no reversing valve wire on any of the wire terminals. In fact, there isn’t an “O” terminal at all.


When you are installing a thermostat on MOST residential and commercial heat pumps, typically the orange wire goes to the reversing valve. However, when you are installing a lite commercial Carrier system there is no need to consider the reversing valve. So, what are we supposed to do with the orange (reversing valve) wire? You will not use it because the system controls the reversing valve on its own.


The defrost control board that Carrier utilizes on their lite commercial products has logic built into the board to take care of the reversing valve(s), you simply tell the unit if there is a need for heat or a need for cool. When these systems receive a call for Y1 or Y1 & Y2 then the defrost board will energize the revering valve(s) as needed. When the systems are given a W1 call for Heat then the unit will crank up in high stage. The unit only has one refrigeration heating stage even if it is a “2 stage” unit. The “W2” terminals on split units are actually not inputs but rather outputs to engage the electric heat strips when the system goes into defrost; on the package units the “W2” is an input and it engages the electric strip heat if equipped.


When it comes time to program the thermostat it should be programed as conventional NOT as a heat pump. If the system has two compressors or a single compressor that does staging, the unit is 2 stage cooling BUT only one stage heating. The unit will respond with high stage heating when W1 has 24vac. Use the chart bellow to help decide the specifications needed for a thermostat to operate your unit:

Conventional Thermostat

With electric heat

With electric heat

One Stage Cooling

2Heat 1Cool

1Heat 1Cool

Two Stage Cooling

2Heat 2Cool

1Heat 2Cool

< Older Post Newer Post >

More to Explore

The EPA 608 is Changing!

September 16, 2026
Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion. 

DLS A2L Dissipation Error Codes

By Jesse Van Atta • September 16, 2026
Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion.