blower seems to die down

timnsher

central air dies down after being on for 1-2 hrs. when left off after few hours will work fine. ac unit outside running, just intermittent forced air. even when just fan only....no air. but will work after shutting off a few hrs.

beenthere

Moved to HVAC forum.

biggles

fan and squirrel cage are clean not packed with dirt dust....sounds like it is over heating if frame is hot to the touch after slow down....

scottmcd9999

Have you actually noticed the fan speed drop during operation? Or when you say "die down", do you mean that is just stops cooling?

Could be a freezeup, especially since you mention that turning the system off for a few hours (and allowing it to thaw) seems to work for a bit. When you notice the system start to fall off, check the indoor section (assuming this is a split system) for signs of ice/freezing. You'll generally see this on the bigger copper line.

timnsher

when i say die down,, i mean no no forced air coming out of the vents. ac seemed to work ok today for a few hrs....then just gradually no air at all ...ac unit outside running.....inside central running.....whats funny is all is fine as long as we only run it a few hrs intermitently....some sort of of freeze up i guess? th e little copper pipe is hot for the most part and the big copper pipe is cold.....covered w/ insulalation but i wouldnt say it is frozen. just cold no more than a cold water pipe at this point. ac worked fine for a few hrs.......now no air coming out of vents. ac unit on. central air on. i can turn on fan on thermostat and nothing will happen no forced air. this doesnt happen in winter with heat, by the way.......only this ac force air issue......................

scottmcd9999

Given what you've reported, my money is on a freezeup. Those are most commonly caused by air flow restrictions (i.e. clogged filters, dirty coils, dirty blowers, etc) and low refrigerant. You can change the filters (and possibly clean the other stuff), but you can't charge the unit or find the leak. You'd need to call someone to take a look at the system.

timnsher

just noticed tonight frost on the big pipe....after running it for several hrs. what does this mean.....is this a simple fix or do i need to call someone.....

timnsher

what i dont understand is how the air flow is diminished regardless of the ac unit . i turn on fan only right now and no air flow at all....

scottmcd9999

See my earlier post re: freezeup.

A "freezeup" is literally just that - the coil in the duct system freezes over, and blocks all air flow. Depending on the amount of ice, it can take several hours to thaw completely. During that time you'll have little airflow, although it will increase as the ice leaves the coil.

Of course, you could have a bad blower or capacitor, which causes the fan to run slowly, which will also cause a freezeup - but, again, that's something you'd have to have a professional check for you, unless you're very familiar with the way evaporator fans should work, and can determine whether one is running too slowly (vs one that is running at the right speed).