Central air vent temperature compared to indoor room temperature - is a 20 degree difference the standard? (Houston: new house, maintenance)

[Zhang Fei]

In other words, if there's a less than 20 degree difference between the indoor air temperature and the cool air blowing out of the central air vent, is it time to add freon to the central air unit? In my particular situation, the difference is a measly 5 degrees.

[tstone]

I've heard it said 18 degrees is the minimum. Not sure if you lack freon but it sounds like something needs to be done.

[HoustonRonnie]

Huh? The time to add freon is when the charge on the unit is low.

Ronnie

[Zhang Fei]

Originally Posted by HoustonRonnie

Huh? The time to add freon is when the charge on the unit is low.

Ronnie

So when do you have the charge on the unit tested?

[jasonamd]

The temp at the output of the evaporator coil compared to the intake air temperature should usually be somewhere between 14-20 degrees cooler. You can't measure the temperatures at the vents and get an accurate reading since the air will most likely warm depending on the location of the vents and how well insulated they are. There are lots of issues besides low freon that can cause cooling problems. But if it is a low charge and it has worked fine in the past, then you have a leak somewhere. If you think there is a problem then all you can do is call someone to come check it out.

[kreeyax]

Originally Posted by Zhang Fei

So when do you have the charge on the unit tested?

I have my unit serviced twice a year. Once around April (before summer) and once around October (before winter). They check everything out then and add freon if needed.

[ethanw]

Same here. I pay a company for twice a year preventive maintenance. This can save you a lot of money..... Even in my new house I still got them to do it and one of the units was low in freon. There was a leak. I called the builder HVAC company and they fixed for free.

Originally Posted by kreeyax

I have my unit serviced twice a year. Once around April (before summer) and once around October (before winter). They check everything out then and add freon if needed.

[TimBomb]

hmm 4.5 years now and I've never spent anything on maintaining the AC. I guess I'm not saving money

[piyf]

If it's a new system I would think the normal air filter change is more than enough for the first 8-10 years.

[HoustonRonnie]

Originally Posted by Zhang Fei

So when do you have the charge on the unit tested?

Once per year, the same time you wash the condenser coils.

Ronnie