Check out some similar questions!

Home repair · Oct 9, 2008, 05:40 PM

I need some help from you HVAC guys.

I have a lady with AC unit outside with one 12" line going to the registers and one 12" return coming in the AC unit.

Some filter material got into the return line and was sucked into the unit, it was smelling a little like burned plastic, probably piece of filter. The unit was also coming on and off about 3 times during each cycle. I pulled the filter out,(it looked whole, and not chewed up), but the on and off still happens.

The air cools great and the thermostat is OK, I put new batteries in it also.

Any idea what is causing the on and off?

Thanks

Roger

acetc · Oct 9, 2008, 06:34 PM

If it is low on refrigerant, it may be cycling on a low pressure switch. Observing the pressures and varifying the call for cooling is the only way to tell exactly what's going on , good luck, Mike

letmetellu · Oct 9, 2008, 07:21 PM

Originally Posted by Home repair

I need some help from you HVAC guys.

I have a lady with AC unit outside with one 12" line going to the registers and one 12" return coming in the the AC unit.

Some filter material got into the return line and was sucked into the unit, it was smelling a little like burned plastic, probably piece of filter. The unit was also coming on and off about 3 times during each cycle. I pulled the filter out,(it looked whole, and not chewed up), but the on and off still happens.

The air cools great and the thermostat is ok, I put new batteries in it also.

Any idea what is causing the on and off?

Thanks

Roger

You said that the unit is coming on and off about 3 times during each cycle, is this on the heat cycle or the cool cycle or is it both. If it is the heat cycle it is probably that some of the material got onto the coil and has cut down the air crossing the heating chamber therefore making the limit switch cut out the flame in the furnace. So if this is not what you mean give us a better explanation and we will try again.

Home repair · Oct 9, 2008, 07:37 PM

Originally Posted by letmetellu

You said that the unit is coming on and off about 3 times during each cycle, is this on the heat cycle or the cool cycle or is it both. If it is the heat cycle it is probably that some of the material got onto the coil and has cut down the air crossing the heating chamber therefore making the limit switch cut out the flame in the furnace. So if this is not what you mean give us a better explaination and we will try again.

It is an air conditioner only, in Arizona, still running near 95-100'. There is a separate furnace.
The unit comes on and cools very good almost instantly, but will run for a few minutes and them off for 5 seconds, then run for a minute the off and so on.

letmetellu · Oct 10, 2008, 08:37 AM

I am sorry but without more info I can't give you any ideas.

Is this a unit that sticks through the window opening.

Also what is it that stops running? The indoor fan motor, the outside fan motor, or is it the compressor that stops. Give me all the info you can.

Home repair · Oct 10, 2008, 08:51 AM

This is an outside air conditioner only setting on a pad. The condenser and air handler (fan) are all inside the unit.

The filter had been sucked down from he infloor cold air return and was inside the air handler. It did not get cut up but was just resting there.

The air conditioner will come on and work fine, give very cold air, but after several minutes of running it will slow down for 5-10 seconds and then start blowing again, and repeat this pattern 3-4 times until it shuts off. It does not sound like the motor is straining, just an on-off cycle.

The unit has apparently run fine for years and never been repaired

Thanks