Air flow weak, and not cold...in ATL

[fix_rocky]

My Carrier central a/c system is almost 30 years old. It's been a real workhorse, and I'm hoping there's still life in it. The inside and outside fans were working, but there was no air flow through the vents. Immediately after I changed the filter which was quite dirty, the air became considerably cooler, and the air flow improved, but was somewhat weak. Now just a couple of days later, the air flow is even weaker and the air not at all cool. Any suggestions? thx....rocky

[mattison]

It's probably frozen up due to the dirty filter. Shut the unit down at the t-stat and put the fan switch in the on position for about 24 hours. After that see if the airflow has returned to normal. If so turn the a/c back on and see how it works.

You may even go to the airhandler and see ice on the fat insulated copper line going into the plenum.

You did put a clean filter in right??

[fix_rocky]

Thanks.....I did put a clean air filter in. What is happening that would cause me to see ice on the fat insulated copper line at the air handler? Also, what does running the system in the "air off" mode do to help the air flow (just trying to educate myself)?.....thx...rocky

[mattison]

Normally a frozen coil is caused by lack of air flow across it. The dirty filter could have started the frezzing process and now even though you've changed the filter there is still a blanket of ice over the coil blocking or restricting the air flow.

Turning off the a/c section and leaving the fan on will thaw out the coil completly, then you can turn the a/c back on to see if it is working correctly. If it freezes over again we can have you check a few more things.

Forgot to mention, make sure the outdoor unit shuts off when you turn the temp up.

[fix_rocky]

Still weak air flow and air in definitely not cold. Any other suggestions? Thanks much!...vr

[TigerDunes]

fix_rocky

A couple of suggestions and observations.

First of all, your AC system is well past its average life.

Is compressor and fan of outdoor condenser unit running?
If so, is the big copper line cold and wet and small line warm?
Have you opened up your evaporator coil to make an inspection?

It is possible that your blower motor was damaged because of either dirty filter or evap coil or both.

What is supply register temperature? You can take this with an inexpensive digital thermometer?

Post back when you have time. Sorry for your trouble.

:(

[fix_rocky]

Thanks for the tips......I ran the just the fan with a/c off for several hours. However, now the compressor and fan of outdoor condenser unit is not running with the a/c turned on. Doesn't seem good(?). Any thoughts? If I have to replace the a/c, should I address the furnace at the same time?...thx...vr

[mattison]

If the furnace is of the same vintage then yes replace it to. At 30 years old I wouldn't sink a dime into a repair.

[TigerDunes]

fix_rocky

Time to call HVAC tech. With Atlanta weather, you have to get some expert relief. I would not recommend spending a lot of $$$ on an AC system this age. You will have to weigh any repair costs. Let us know what diagnosis is. May not be as bad as you suspect. Will keep my fingers crossed for you.

Yes, I agree with Matt. If furnace is same vintage as outside AC condensor, then you should consider a complete matching system of same manufacturer if AC is ready for proper burial.

Good Luck!
:)