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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8164
Experience:  Furnace, A/C and heat pump specialist.
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Have an a/c unit model Rheem RGRM-07EYBGS, when the blower

Customer Question

Have an a/c unit model Rheem RGRM-07EYBGS, when the blower starts it makes a noise as if is trying to start making a woosh noise then it kiks in. I asked the a/c person that install it He said it was normal because it is a 95 %. It does not sound normal
to me. Also, I would like to change the outside unit model 14AJM30A01 to a two stage unit. My reasoning, I want to have the a/c runing in 1st stage a lower blower speed. The noise right now is drivig me crazy. But the unit calls for a minimum of 1000 CFM.
Any suggestions. By the way is an upright hallway unit next to my bedroom.
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.
The noise you are experiencing with these units is normal.Often the motor will even have a "rocking' sound on start up or shut down. The motor is what is known as an ECM motor. It does not have speeds as such, but rather the rpms is determined by DIP switch settings on the control board that control the motor though low voltage or DC voltage depending on the motor.
The control board will automatically determine cfms motor needs to move based on these DIP switch settings.
Customer: replied 2 years ago.
So, what is the solution?
Expert:  airheatman replied 2 years ago.
Unfortunately you can not replace the ECM in these furnaces with a normal PSC motor. I know this is not the answer you hoped for, but I can only provide accurate information.
I am not trying to be a wise guy or be rude, but the options are to try to get used to the different noise this unit makes or replace it with a lower efficient furnace that uses a PSC motor.
Customer: replied 2 years ago.
That is the problem, is eather off or full speed, how can I convert the a/c part to a two stage to get the blower to work at 50 to 60% of what he is working now.
Expert:  airheatman replied 2 years ago.
Have you tried adjusting or has installer tried adjusting the dIP switches?
Customer: replied 2 years ago.
well I did move the 5 & 6 dip, but what I was advised last someone in your organization was not to lower it to much because the unit requires a certain amount of cfm otherwise it may ice/freeze
Customer: replied 2 years ago.
are you still there?
Expert:  airheatman replied 2 years ago.
THis is true. I believe on this furnace you can change 7 and 8 to adjust a small amount like 10% up or down. You might experimenet with those.
Customer: replied 2 years ago.
About changing the outside unit to a two stage with a communicating board
Expert:  airheatman replied 2 years ago.
That might help with the operating noise at the times when temp is not very warm outside and only first stage is required, but on days where temp is say 85 or higher and second stage is needed, we still have to maintain the 1000cfms.
However, you will still experience some of the rocking and swooshing on start up as that is just characteristic of the motor

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