AC/Heat Unit Block of Ice?

[Conservator]

Anyone have experience with their AC/Heat unit freezing over? 3" thick! Just my luck... with the beginning of the coldest 2 weeks of weather seen to this area since I moved here ('97)...

[joedog]

I know it sounds stupid but shut the unit off for 10 mins then for about an hour cut the A/C on once it melts off wait 10 more cut the heat back on. In the morning call the heat and air company of your choice. Your low on freon or what ever new stuff may be used in your unit,

[Deleted]

Heat pumps are supposed to go through a defrost cycle. It sounds like yours has quit doing that and needs to be repaired.

Here are some possibilities -

Bad defrost control or timer
Bad defrost thermostat or sensor
Bad defrost relay
Sticking reversing valve
Bad reversing valve solenoid coil
Bad outdoor fan motor
Low refrigerant charge
Restriction

as told by this link.

Chris of Malone Heat & Air is very good, nay, topnotch. 423/624-6647

[Deleted]

Let us know what it turned out to be - what it took to fix the problem.

[Conservator]

Thanks guys... Called my regular guy who fixes my AC/Heat unit once a year. Usually when it's 98 degrees though, not 18 degrees. He did an override to see if it would defrost and it did... rather quickly actually. (well, the outside anyway, the inside still had a few inches of ice when he left). But he narrowed it down to being a bad sensor, (which he didn't have on him) - and it wasn't going into defrost mode like it should. He also added 2 lbs of freon. So $140 bucks for two visits, the sensor & freon. Sounded fair, I guess. ?

[Conservator]

I wish I took an AC unit repair class in school... I would have saved many $ over the years.