wrote in message
oups.com...
We completed construction on our home in Florida in 7/2006. We have 2
Bryant central air units (one 3 ton unit and one 4 ton unit). Last
week I noticed the 3ton unit couldn't keep up with the cooling during
the afternoon hours.

1) Ask the installing company for a copy of the heat load calculation that
was done when the 3 ton unit was sized for the space that is being air
conditioned. That's the only way you'll know if it was correctly sized for
the application.

2) What is the return-side temperature at the air handler? If it is more
than a few degrees over the air temperature measured at the interior return
grill(s), you have a duct leak on the return side.

3) Has the supply plenum and duct work been checked for leaks?

4) Any competent contractor can take a eight or so readings (of pressures,
temperatures) and determine what the problem is without any guessing.

5) With an 18 degree delta-T I seriously doubt that you have a defective
reversing valve. Don't let the contractor hack into your system unless
Bryant confirms that this is the cause of your problems.

Good luck - it sounds like you will need it.