Residential coil freeze 1

[MarauderX]

We have a residential system where the coil keeps freezing up overnight. The air flow is good and the filters have been changed... what are the other possibilities of things gone wrong? Is the night set-back requiring too little air flow and then the coil freezes? Or is there something wrong with the system's refrigerant charge or flow?

 

[rogzog]

Check this link, I think it will answer your question.

http://www.toad.net/~jsmeenen/ice.html

TOK

 

[lilliput1]

I was at a hotel in Boston when I was awaken by loud rattling sound. The sound came from the Carrier console heat pump. I took off the front cover & found the top half of the coil frozen over. I noticed the bottom half has a sensor at the face of the coil & that this coil half is not frozen over. I indexed the heat pump to the heat mode and it melted the ice. I moved the sensor to the top half of the coil. The unit run quiet from then on and we spent (3) nights in the hotel. I also found out that this must be happening to a lot of units in the building because the wall was vibrating and outside you can hear a lot of noise comming from the heat pumps.

 

[sterl]

If the unit worked well on a hot summers day, when it was near new...and cools but frosts after a period of operation now, the culprit is probably one of the following:

They're set too cold: AC units not suitable for meat or beer aging...

There's not enough air flow; and besides the filters, return air grille, supply air obstructions and so on, the other check is on fan condition, speed and similar.

The condensing temperature is too low, which happens to quite a few heat pumps in places like Boston: in effect, the capillary tube cannot pass refrigerant fast enough at the reduced inlet pressure; the suction pressure goes low and refrigerant backs up in the condensing coil until some portion of heat exchanger is crippled, raises condensing pressure but low side is now short on liquid refrigerant.

A blocked liquid line drier, causes same effects as above.

A shortage of refrigerant charge.

There are a couple of others, including poor air distribution...