Air Conditioning - fan on auto, intermittent

The handler fan goes off perodically. I have yet to determine a pattern, and usually we don't notice it right away. Suddenly it dawns on us that its warm in the house. Meantime the compressor is running, and recently had some water leak on the ceiling. I read here how running the compressor without running the fan is bad, so...

Tonight I decided to take it off "auto" and put the fan on "on" Seems to run fine that way. Anyone have an idea why on auto it goes off like that?

Thanks in advance.

To set the themostat fan switch to "ON". The problem, most likely, is the fan relay and it could be the thermostat itself. Do you have an old style lever thermostat? I wouldn't recommend buying a new thermostat or fan relay until you can prove which one it is. I've been changing fan relays steadily around these parts, especially in the Janitrol brand. Intermittent problems are the worse, keep the fan switch where it is until the problem is solved.

Thanks for the reply. I bought a new thermostat a few months ago, and decided to install it last week. Unfortunately it didnt solve the problem. That means a relay then eh? I'll check the schematic and try to figure out where it is. Will keep you posted on my progress :)

First thing I would do is find out why the water is on the ceiling' Your condensate drain may be clogged, and drain over filling.This could be causing your fan to be cycling on a safety. I'm assuming your air handler is in the attic.Check the drain first.

The handler is in the garage, very easy to get to. The cold copper line that is insulated was dripping wet and very cold, and has stained the ceiling where it pentrates into the attic. The access to the attic is right above the handler, so I went up and followed the line visually and sure enough it travels and bends right where the stain in the bedroom ceiling occured. I can't actually get in there as it is a high ceiling at that point. So I have 2 water stains in the ceiling, both small though.

The condensate line travels a different way, and in fact I had some clogging there a few months ago. I cleaned that out and haven't had trouble since. I did suspect that line at first though.

I think what happened was the compressor was running but not the handler, so the freon got real cold and this being summer in south Florida, well you know... Thankfully I read on these forums that eventually my compressor would be damaged that way, so for now I'm running the blower constantly.

This is a "Goodman" system. I've never tinkered with air conditioners, so have no idea what the delay looks like. Or where to buy a replacement. I did open the panel up last week to look around, but didn't see any obvious damage. Meantime I took out the manual that was there and managed to misplace it :confused:

Out of the box here. But if it runs ok on fan on ,thats the same relay as for fan auto when it turns on with AC. Could be the tstat but most of the time its not. If you cant find the schematic. Open up the blower unit there and have some one turn just the fan at the tstat to fan on and off and on and off. Should find it hearing the click.

ED ;)

I think I've isolated the relay. Could it be called a blower time relay delay? The schematic is on the panel, and I've done as you suggested and listened for the click. So are these relays easy to find/buy?

Dont suppose H/D sells them :D

You got it. Blower time delay. Any hvac shop should have them . Dont know if you can buy from Johnstone Supply or not thehy have them. Dont think HD or lowes has them.

ED ;)