John Gilmer wrote:
"Tony wrote in message
...
Tony Hwang wrote:
Hi,
After days of lousy wet weather sun came out today and got hot.
a/c just kicked in this afternoon. Air cleaner is cleaned, filter
is replaced. All looks, sounds alright. Measured temp. between cold air
coming out and warm air returing at the upstairs registers. ~17 deg. F
Is it Okay? Or need to call for service?
TIA,
Hi,
Sorry I meant to say the temp. diffrence between two reading is ~17 deg.
F.

That's a bit on the low side. If it's not a relatively new "high SEER
machine," the air one the cold side of the air handler should be between 40F
and 50F. (Older machines keep the humidity down by cooling down to 40F.
Newer machines don't take out as much moisture but make it up by handling
more air.) If the air is quite "moist" the outlet temperature will be
higher. The machine can't outlet air cooler than the "dew point" of the
exhausted air. If there is a lot of moisture in the house, it might take a
day for the machine to bring down the humidity before it can do the serious
cooling. You can check to see whether condensate is coming out of the air
handler. No condensate and relatively 'warm' air (60F or higher) usually
means the machine isn't doing much.

Unless the air intake is really, really poorly positioned, it should be
sucking up "warm side" room air somewhere in the high 70sF.

Doing the math says that your machine ain't acting right.

Obviously, you are trying to save the cost of the repairman. You may have
poorly insulated ducts which means that the cooled air heats up between the
air handler and your rooms. That's why I recommended measuring the
temperature at the air handler. (you can drill an access hole in the duct
work for your probe and cover the hole with metal duct tape when you
finish.)

If it keeps you comfortable, then I guess it's "gud enuf." If it doesn't
keep you comfortable, call the repairman.



Hi,
Thanks for the heads up.