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Variable speed Amana seems to run only one speed

Adam Policky
14 days ago

I had a new heat/AC system installed in January and opted for the most expensive option offered with variable speed compressor, condenser and blower motor. In addition to energy savings, I hoped to see a substantial difference in the amount of on/off cycles and have the system run at quieter lower speeds when possible.

This new system replaced an older 1-speed Trane furnace with no AC (swamp cooler instead), and the first thing I noticed in January was that the new blower in heat mode was not at all quieter. Now that it has been used in heat and cool modes I can say that there is never a time when I can detect a noticeable difference in fan speed or noise level, so I'm unsure if the fan is really varying speed. It seems to me that it jumps on and off as suddenly as the previous system and no better than any other I've had in the past.

I shared these thoughts with the person who sold and installed the system and was told over email, "the system runs as promised, there is no way you would know the fan speed unless you were into the diagnostic side of the controls". Am I wrong in thinking that the fan speed change should be noticeable just by its force and noise level?

I don't want to be a whiner or pretend to know more than I do, but I'm unhappy with the real-world results of the system, and am trying to decide whether and how to pursue the issue. Here is more technical detail on the system:

NLP 5025 AVXC20-36-V

Amana® brand 3 Ton, AVXC20 vertical A/C system with variable speed furnace, mounted on roof

Amana AVXC200361, CAPF3743C6, AMVC80805CX

I believe the middle one is the heat pump and blower unit? Showing my ignorance here ;) -- just pulled these codes from the project quote.

The Thermostat is an EcoBee 3 lite. I have access to the logs and as an example, on a recent day with an outside high of 88 and thermostat set to 72 it turned on/off 36 times (18 cycles). The longest run-time was a solid stretch of 150 minutes where it kept indoor temp nice and stable with outside temp at 88. But at other times it cycles much more and does not noticeably turn down the fan to adjust.

The logs always show the state 'compressorCoolStage1On' when on -- so there is no info there on what speed the fan is running at and I do not know if the thermostat is controlling the fan or if that is happening elsewhere in the system if at all.

I'm hoping someone far more knowledgeable than myself can weigh in on whether this all seems reasonable or if there is something wrong and this system is not performing properly. I would love to trust my local rep, but his attitude when I posed the question was overly defensive and did not help to clear anything up.


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