Two-Stage Furnace Air Conditioner Thermostat Control Problem | Hi I was wondering if you can help me with a two thermostat… because I don’t think my condenser is using the second stage…. I open the thermostat and see the jumpers, but is there a way you can illustrate my brain and the correct set up I have an Amana 16 seer 2 stage 5 ton units and no one seems to understand this unit,

I went into the attic. found my models my Condenser ASXC160601BC serial #1307225441 Is a two-stage scroll compressor cooling. my furnace is model AMVC950905CXBA serial #1307131781 two-stage gas furnace burner variable speed blowers… this is how is wired at this moment:

Two-Stage Furnace Air Conditioner Thermostat Control Problem


From Condenser
Red-Red, Blue-Com, Purple-y1, yellow-y2 are the wires in the condenser.
the way the cables were connected is as followed.

to the air handler
R to R, blue to common, now Y1 was used as green cable and is connected to Y1, then Y2 is yellow cable and connected to y2 in the air handler.

from the air handler: to the thermostat
R to R, C to C, G to G, w1 to w1, w2 to w2, y1 to y1, and y2 to y2,

Firstly, I feel this is not correct how is the two-stage going to kick in.

Next, I feel cool stays in first-stage forever, and my heat throws too much air… I hope you can help me because no one can.

Finally, I was wondering do I need jumpers in order for the two-stage to work… either for furnace or cooling?

Two-Stage Furnace Air Conditioner Thermostat Control Problem | Response

Thanks for contacting High Performance HVAC and asking this question!  Some people have serious issues understanding the programming function of their thermostats. Here I will attempt to explain it in layman’s terms so hopefully, you will understand it.

As far as navigating the programming option you will definitely be at the mercy of the writer who wrote the thermostat instruction manual. Hopefully, it is clear and concise and you easily make these checks I will describe to you.

Taking things to step by step here is what you need to do first:
Two-Stage Furnace Air Conditioner Thermostat Control ProblemSince it appears the thermostat is wired correctly based on your vivid description you need to check the thermostat.

You will need the installation manual for the model of the thermostat you currently have to check the appropriate settings. You simply need to make sure the thermostat is properly programmed to make sure it is functioning correctly.

Staging Control | Two-Stage Furnace Air Conditioner Thermostat Control Problem

The control for staging is in the thermostat and is temperature-based. From my experience, this is typically set up during the initial installation. If the settings in the thermostat are not correct then the system will not stage properly. The picture is a screenshot of a Honeywell thermostat installation manual. If this was your system that would be the setting for your system for that particular thermostat where I got the screenshot.

By the way, there are many different types of heating and cooling systems as shown in the below screenshot graphic from the same thermostat manual.programming thermostat equipment type

Differential Temperature Settings | Two-Stage Furnace Air Conditioner Thermostat Control Problem

Next, you will want to find the differential temperature setting that controls the second stage. This too should be a setting in the thermostat. I set most to a 3° F. differential setting. In other words, if you set the thermostat for 72° F. it will run at a single stage.

As the temperature rises, while running on low, when the thermostat temperature rises to 75° F then the second stage will kick in to bring the temperature down. This works the same way in heating except on a temperature decrease of 3° F. Then the second stage heat will kick in the satisfy the thermostat.

Check your thermostat setting for this differential setting for cooling. While you are doing that you may as well check it for heating also. Make sure it is set for the 3° F. differential setting from the single-stage to the second stage. You can adjust that differential if you want and in your case, you may want to make it a 2° F. differential temperature setting.

Scroll Two-Stage Wiring Diagram

Two-Stage Scroll Wiring Diagram

The wiring diagram for the Copeland Scroll Two-Stage Compressor

Once you have done that hopefully, you will have solved your problem. If not then you will likely have to call an HVAC technician to make the following check. It is testing the two-stage condenser control board and solenoid in the condensing unit.

That Amana has a Copeland Two-Stage scroll compressor. It uses a solenoid on the compressor to switch a plate inside the compressor. The plate has a small hole and a big hole. The big hole is for the second stage while the little hole is for the single-stage or low stage.

Two-Stage Scroll Compressor Solenoid

Look at the graphic for the wiring diagram to your two-stage scroll compressor. On the right is a circle with a “C” and then underneath that is a circle with a “Y2”. The “CS” under that stands for compressor solenoid. This is what makes the plate switch inside the compressor. I’m not 100% certain but I believe it works on 12 volts dc power.

I’m not sure if it has a rectifier at the solenoid or if the dc voltage originates from the control board??? Maybe one of our readers can answer that question. Anyhow, that’s how the two-stage operation works.

Control Board Solenoid Control

If the solenoid goes bad or it does not receive the control voltage from the control board then you will not have staging for your air conditioner. You really need a technician who knows what they are doing to test the solenoid for proper operation. If the problem is not your thermostat or settings of the thermostat then this needs to be tested. Firstly, I would test the control board.two-stage Amana condenser control board
Then I would test the E24 terminals for proper output voltage after making sure the thermostat settings were correct. I would turn the thermostat setting down while it is in cool mode. Turn it down to say 60° F when the temperature in the house is far above that temperature.

Then I would check the voltage output at the E24 terminal. This would tell me the solenoid is getting the proper voltage. To make sure the solenoid is working correctly you need more tools and this is why you need a good HVAC technician to make this check.

Basic Checks | Two-Stage Furnace Air Conditioner Thermostat Control Problem

You may also want to check the thermostat wire to make sure it is good especially at the terminations. Thermostat wire is 18-gauge solid copper wire and over time it can become brittle. Sometimes the wire could look good but it is broken. A little tug on the wire will make sure it is not broken.

Variable Speed Blower Speed | Two-Stage Furnace Air Conditioner Thermostat Control Problem

You mentioned the fan is blowing too much air in heating mode. This has nothing to do with the thermostat. It has everything to do with the DIP switch settings in the air handler for the variable speed ECM blower and it is controlled by a control board in the air handler/furnace.

The control board does take its basic commands from the thermostat and then sends the appropriate signals to the ECM (Electronically commutated motor) which is a DC motor.  Direct Current as opposed to Alternating Current which is found in your home for nearly everything.

Anyhow, if the DIP switch settings on your control board are not correct then your blower will not function properly in whatever mode it is set for, heating or cooling. These settings are supposed to be adjusted by the installer when they install the system and take into account several factors including the size (BTU/h output) of the system. See the image below for a screenshot of an example of the proper settings.

This needs to be set up for your specific model number and size. From what you are telling me whoever installed this system did a poor installation job. This is why I recommend all my readers who purchase new HVAC equipment to get a good contractor to install their system. It is why I wrote the HVAC Consumers Buyers Guide.

Amana Variable Speed ECM Blower Control Settings

Giving everything a basic check never hurts anyhow. Good luck and I hope this helps you solve your problem.

High Performance HVAC

Two-Stage Furnace Air Conditioner Thermostat Control Problem