Gas and Oil Home Heating Furnaces - Central Air pipes inside and outside house are freezing every so often

The pipe coming out of the blower in the house and into the compressor outside freezes up every week or so which prevents air from coming through the ducts. I just defrost the pipes and shut the unit down for an hour or so and then it starts to work again.

What would be causing the pipe to freeze. There is insulation on the pipe and I have cleaned the debris around the unit so that there is no obstruction. Any help is appreciated.

replaced air filter or clean cooling coil?PDF

I took apart the outside unit and shop vac'd the coils outside which were full of leaves and mulch. I then replaced the internal throw away filters I use and then opened the air handler unit and used compressed air to blow the intenal coils clean.

Hopefully this helps but I will find out in a few days with the heat. If it doesn't work then time to call in the pros since I am out of fixes that I can do.

Thanks for your reply.

You have one of two problems. You either have a dirty evaporater coil or you are low on freon. Clean the evaporater coil and check the refrigerant pressure the low side sure be between 70-80 psi, the pressure at the high side should be between 275-305psi.

Thanks for the reply. I have called in for the pros but with these two reccomendations at least I can steer the tech to what has been done and what he should look for although if he is a pro he should know.

I wish I had the equipment to check freon and such so I can do it myself but everyone has their limits.

Thanks again.

Well the tech came by and filled upo my Freon and believes there is a leak in the Coil I guess on the outside unit. He did not want ot take the outside unit apart instead he wanted to see if this happens again. In the interim what does the coil look like in the outside unit and would I be able to tell if there is a leak in the pipe?

If so how do you repair the leak, sealant of some type, any reccomendations?

is leaking you will be back to square one in less than 72 hours.PDF

How can I tell if the outdoor coil is leaking? Will there be some type of stain, grease, water, etc. If so what do you seal it with?

What about if the leak is inside the air handler, same questions if you happen to know.

Is the coil in the outside unit the fuzzy type material that surrounds the unit or is it a copper looking pipe?

electronic leak detector.No matter where the leak is you need to sniff it out.Soap bubbles will work but without an ELD it will be very difficult to locate.PDF

Thank you for the note, can I get that ELD at Home Depot or a specialty store?

If it does have a leak you might see some oil staining around the leak. He should have been able to find it with a good leak dector. Be carful though he might be trying to pad the bill be adding more and more freon.

In my experience over half of the gas lost from units leaves through the service access ports where the tech connects the gauges.

The ports use a valve much like an auto tire valve. They often leak slightly. The manufacturers cover the valve with a finger-tightened cap with a rubber gasket. The cap is often lost, loose or missing the rubber gasket.

The valve area is often oily because the tech doesn’t wipe of the oil that is release when the gauges are removed. This makes it hard to determine why the valve area is oily. An oil mark could be evidence of a leak since leaking refrigerant usually carries enough oil to mark the general area of the leak.

Thanks for the insight. I'll look around the units inside and outside the house and see if I can find a service access valve or something like that and see if it looks oily. Have you ever used an ELD (electronic leak detector?