If the speed of the fan motor is set by moving a wire onto a different tap, what you describe could probably be dome with a 24V SPDT relay running off the 24V compressor wire. Leave the fan tap on a low speed setting until the compressor comes on and switches the tap to a higher speed. Not a pre-made circuit to purchase; one would just wire the relay into the unit.

Thanks, sounds just like what i need…not sure if I need additional leads besides (input G-fan, Y-cool) or what the amperage should be. Any suggestions from this list?

https://www.newark.com/c/switches-relays/relays/power-relays

Thanks!

You need to determine whether the air handler has a PSC or ECM motor. For the PSC (permanent -split capacitor) the taps wires are powered by 120 V. The ECM (electronically commutated motor) usually uses 12 V tap connections. However in the case of a variable speed motor that might be no taps. The next step is to find the wiring diagram for your air handler and figure out how the motor can be controlled.

I am curious as to what on off sound are you hearing. For a 1.5 ton AC you could set the air flow in the 500-600 CFM range. I would not think that would be too loud unless the duct work is undersized. Do you know what is the current air flow and what tap setting is being used?

Get a ceiling or room fan. Keeping the blower going will raise the humidity level of the interior, thus providing less comfort.

No good will come from an untrained homeowner fooling with anything inside of or concerning a piece of HVAC equipment.

I would suggest this relay. It looks to be an HVAC relay, 3/4 HP contacts should be plenty for a typical residential squirrel cage blower and the price is right.

https://www.ebay.com/itm/274534060950?hash=item3feb815396:g:n1AAAOSwTmBfh1fX&amdata=enc%3AAQAHAAAAoPrt4NSOQX7uWuMG%2F8J2nMI33sq4SVNORK6asvzv5a9X3GIFzFIylLbwJOVGsulbn0azkvwvaOLhjl9CnDRgF%2BUR9SLWCiQ%2FZ%2F0YhO3seif9XwWAzEVGGSIr4HLSin%2FWkP1oh%2BpOhBtDnrK%2B8aDgbjocGi3qGnjCYIPd9uVr7nJzpbv2RBk4DIWHH0pl0s4gSsDsg6lElR0X3%2B0RCteyor4%3D%7Ctkp%3ABk9SR-rBxrTAYA

This relay is setup to control a single damper in a downstairs zone… could one of the board relays be utilzed for the purpose of making the fan run at low/high speed?

The schematic is showing a 2-speed PSC motor. The note at the lower left explains how to change the speeds. The black wire selects the high speed, the red wire selects the low speed. You would have to install a relay which controls which of these wires will be connected to control the speed. The relay could be controlled by the connection back to the Y terminal of the thermostat.

" Elmer J Fudd said

Get a ceiling or room fan. Keeping the blower going will raise the humidity level of the interior, thus providing less comfort.

No good will come from an untrained homeowner fooling with anything inside of or concerning a piece of HVAC equipment."

That's advice worth repeating. No good will come from an un,,,,,,,,,,,,,,,,,,,,,,,,,,,

Matt you are going to screw around and let the smoke out then come back here wanting to know how to put it back. If you can't afford hiring a pro,cut your own hair and use the money saved to hire one. Better still set a box fan by your bed to mask on-off cycles like Elmer suggested.

Hi, Matt,

First, continuously operating your air handler's blower can have both benefits and drawbacks. The benefits are continuous filtration and more uniform temperatures throughout the home. The drawback, in addition to the additional operating cost, is that operating the fan after the compressor has shut down in A/C mode can re-evaporate condensation on the coil and raise relative humidity as Elmer noted above. That may or may not be a problem depending on the outdoor conditions. You can purchase a cheap thermo-hygrometer for around $20 and check to see whether it is.

I suggest you investigate the Rescue Ecotech motor. It's an ECM that's a drop-in replacement for a PSC motor. I believe the on-board motor controls don't require you to design nor to install relays or other separate controls. Whether you choose to hire a tech or install it yourself is your call--or maybe your wife's depending on your past history with DIY projects.

Guys, I truly appreciate all your comments. I’m pretty handy with most all electronics/mechanical, but would certainly rather have a HVAC pro do the work. I have contacted several HVAC companies that were unable to figure this out so far. Anybody here local?

Back to the original prblem, the sytem may have been oversized, as the condenser unit comes on for short frequent periods, blows the air very fast, chills the space fast, but then it gets hot/stale before it kicks on again. As a comparison, my A/C unit for the downstairs is very quiet (almost silent), and provides a steady even temperature. Granted, upper/lower levels in a house can make a huge differance.

All of your comments allow me to make a well informed decision on how to proceed! … hence true value from this forum.

May I suggest an idea. You could try setting the blower to low speed and see it how it works. Monitor the coil for a freeze up. If it begins to freeze you would put it back to the high setting. At the low speed the AC will likely have longer run times. This would give better humidity control and efficiency.

I like the ECM motor idea! I see they only come with a 2yr warranty, although their life expectancy is > 10 years. My existing PSC motor is over 10yrs old and still running well (knock, knock). Are ECM motors more susceptible to power fluctuations (spike/brownout,etc)? Now I just need to find a local installer.... :)

When I got married I came with no warranty. 24 years later, here I am still working hard for the missus!