Printable View
Hi Guys. I normally work on commercial refrigeration plants, but was asked to look at a Daikin heat pump because it kept on icing up (outdoor coil) on heat mode. I reclaimed and recharged the system so the critical charge is good. The sensors (coil and ambient) test out ok.
The whole coil is icing evenly except for the bottom 200mm where their is no ice.
Could this be a sign of a blocked capillary which is not cooling the defrost sensor to bring in the defrost?
Did you checked air quantity at outdoor unit when it is normal operating mode (heating)?
This is how heat pump looks when there is no sufficient air flow.
http://farm3.static.flickr.com/2051/...55a71725_d.jpg
Could be, the coil sensor is normally down the bottom of the coil, and systems usually start frosting at the bottom. Did you manage to get a look at the distributor to see if it's unevenly iced up or get pipe temperatures.Quote:
Originally Posted by Drew
Is this system a TX valve or electronic valve with 1/4" tube distributors, or no valves and just small capilaries from the liquid line?
I'm not a daikin expert, but usually posting the model number will get more useful advice from people here.
How big is this coil, is 200mm 25%, 5% or what? Is it a single sided coil, or wrap around etc and where else is iced up/not iced up (ie other coils from the same distributer feed, suction line etc)
edit: Could you remove the coil thermistor from the bottom, cable tie it to a frosted up section of coil, cover it with cork tape and verify auto defrost works? If the rest of the coil is icing up then this should test that the thermistor and PCB ae good.
It has proven to be a blocked capillary.
Thanks all.
Thanks paul. That is how i did prove the fault . Once the client noticed that it wasnt icing up on cold nights anymore we knew the system was defrosting ok and we then found the blocked capillary.