Question about Friedrich M18CF Split System Air Conditioner

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Friedrich air conditioning - inside unit ice build up

I own a Friedrich air conditioning system with an external and internal unit. The system works well, but after 2 or 3 days of use, the internal fan blowing the cold air starts to make a rattling noise due to ice build up which gets in its way. After I shut off the system, the inside unit drips as the ice build up melts. I have cleaned the filters and this is not the problem. Please advise what would cause such a problem and potential solutions? Thank you.

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Re: Friedrich air conditioning - inside unit ice build up

Hi, Reduced air flow, low on freon or being continuously run during cooler weather such as at night. Some people turn their thermostat on 60 thinking that it will help get it cooler faster. They freeze up at night and don't get a chance to thaw during the day. It needs set no lower than 75 or so. The evaporator may be dirty. Don't know a lot about your particular unit but if the outside unit has the compressor and refrigerant lines running to it, The large refrigerant line should sweat all the way to the compressor if its fully charged. Please rate me if I have helped. Good luck kstfas

Posted on Aug 28, 2007

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Re: Friedrich air conditioning - inside unit ice build up

You may have blocked a return vent with furniture or something if so pull it away from the wall a little bit but you have to let it thaw all the way out before you turn it back on

Posted on Jan 07, 2014

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Re: Friedrich air conditioning - inside unit ice build up

1.Improper airflow (dirty filter,faulty blower fan, closed or blocked registers,etc)
2.Low refrigerant charge (possible leak)
3.Restricted liquid line (kinked)
4.Clogged filter/drier
Can all cause freezing of the evaporator (indoor coil)

Posted on Aug 22, 2013

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If the unit is running in cold weather than there is ice building up on the coils located outside. This is normal in that the unit is running in heat pump mode heating inside and cooling outside, After the unit detects the ice build up it briefly reverses the cycle heating the outside coils melting(defrosting) the ice which you observe as water on the pad.

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Our Quietmaster 's cooling works for a while and then doesn't.

Remove the front cover and make sure the temp sensing wire is in place on the front of the evaporator coils. If it has fallen and is touching the evaporator plumbing the unit can preform as you described.

Also check for signs of icing / ice build up on the evaporator coils after the uint has run for a couple of hours. Ice build up will also cause this symptom. IF you do find that the unit is icing up that can be caused by:
1. A very dirty evaporator
2.. A clogged Air filter
3. Contaminated by internal plumbing debris / clogged freon passages
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5. Freon Pressure and return lines touching together usually either on the side of the unit or just behind the center chassis air wall enroute to the compressor.
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As you can see above there are several things that can cause the symptom your described. It cetainly sounds as if you either have an icing problem or a control board problem.

The next time the symptom occurs... place the unit of fan only for at least 30 minutes and then see if you can switch it to cool, and actually have it cool. If it does cool properly after switching to fan only for 30 minutes you most likely have an icing problem.

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As with the simplest way to thaw ice is with heat.

If you are running this unit in cooling and have ice outside, then you most likely have a freeze up inside as well. If this is a heat pump unit, then frost is normal during operation, however, ice build-up is an indication of a problem.

There are 2 effective ways to remove the ice build-up. The first is the simplest. Get your water hose and hose it down. Be sure to turn off the breakers to the unit and avoid spraying the electrical compartment. If you have the ability to hook the hose into a hot water line, then this process with be extremely fast. Let the unit sit for about 20 minutes to dry out and turn it back on.

The second can be a little more complicated if your not tech savoy. You can turn the system on in the cooling mode. This will make the outdoor coil the condenser section. Then, either block the airflow through the coils with an object, put an object over the fan to increase pressure, or if you can, disconnect the fan so it does not run. This method is essentially the same as a defrost cycle.

As with any failure, you can fix the problem at hand, but it will return. After you get past this, your real challenge will be determining what caused the freeze-up.

If you were running your system in cooling already, then you will need to ensure the system has de-iced on the inside as well.

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