Home AC Question

[vaskidmark]

The ac unit in my apartment has apparently gone on the fritz.  I cannot get much cooler than 15* less than the outside temperature - and that's the lower level.  Forget about the 2nd storey.

The maintenance guy says that the unit is blowing 59* at the vents, and the return is 70*, so the unit is "within spec."  I have no idea what "spec" really is, or if such a thing exists, but I have my reasons to doubt his statement that the ac is actually working properly - because a few weeks ago I could keep the place at 65* and only worry about the electric bill instead of sweating through the afternoon and night.

What should I be asking (telling?) the maintenance guy, other than I say the ac does not work and he says it is "in spec"?   So far he has not put any guages on the outside compressor unit - just looked at it and said "Hmmm."

Other than being a pain in the butt with repeated requests for maintenance, what ideas can you suggest?

Thanks.

stay safe.

skidmark

[ilbob]

The ac unit in my apartment has apparently gone on the fritz.  I cannot get much cooler than 15* less than the outside temperature - and that's the lower level.  Forget about the 2nd storey.

The maintenance guy says that the unit is blowing 59* at the vents, and the return is 70*, so the unit is "within spec."  I have no idea what "spec" really is, or if such a thing exists, but I have my reasons to doubt his statement that the ac is actually working properly - because a few weeks ago I could keep the place at 65* and only worry about the electric bill instead of sweating through the afternoon and night.

What should I be asking (telling?) the maintenance guy, other than I say the ac does not work and he says it is "in spec"?   So far he has not put any guages on the outside compressor unit - just looked at it and said "Hmmm."

Other than being a pain in the butt with repeated requests for maintenance, what ideas can you suggest?

Thanks.

stay safe.

skidmark

If the return temperature really is 70 degrees, what are you complaining about? You may have some kind of issue where there is some kind of short circuit in the air flow so the room is not cooling, but the air right near the return is. maybe a fan would mix things up better.

[mfree]

Yeah, sounds like a flow problem to me. Where's the closest vent to the return, and how strong is the flow?

[Brad Johnson]

15 to 20 deg temp diff (return vs outlet) is the normal range.  I agree with everyone else, seems like a flow/balance issue.  Maybe 280plus will be by shortly with an opinion.

If the temp delta is good, airflow problems are your next concern.  Check the filter.  If that's good, make sure the return isn't blocked.  And then open all your doors.  Sometimes closing off room(s) or vent(s) can create funky airflow issues.

Brad

[mfree]

A good example of flow issues... the ducting in my house is generally well designed; it tapers towards the ends to preserve velocity, no funny routes, etc.

Trouble is, it was modified later on with vents for the cut-in basement, right in the big feeds for the other side of the house from the blower. If they're open more than a crack, then the basement gets everything and the rest of the house gets a trickle.

With *that* fixed, I got to tackle the issue of the AC blowing doors shut and rooms going 60 degrees

[280plus]

18* Temp diff is considered optimum. Less means there is more air than cool and more means there is more cool than air. +/- 3* is considered ok. at 21* you are marginal on insufficient air flow. Could be a dirty evaporator, filter, fan running slow for some reason, or a partially frozen evaporator coil maybe. He should have put gauges on it to check for low suction pressure. Hope this helps. If not ask more questions.