Help! American Standard 18SEER

[smoke]

On another note, what company is turning away a service call? At least send some out to check out the system and gain a customer.

~smoke~

[JMack13]

They turn lots away if it is more than a 15 minute fix or if they cant sell them a new unit. I know why its not defrosting, The question is why is the top freezing and the bottom not?

[ga-hvac-tech]

Good to hear Trane is Demand... we do not have many HP's around my area.

Usually the outdoor coil is split into 4-5-6 parallel sections... big manifolds on the side. Should be similar temps all up and down.

Let us know what you find! THX

[drife678]

my guess is that the house has no gutters and the melting ice is dripping right on the center of the heat pump.

[rglasgow]

The rain freezes on the top and not the coils. It has no way of defrosting the ice and it just collects until it interferes with fan blade.

[catmanacman]

hope he already turned it to emergency heat

[Brent Ridley]

This issue could be caused by several things. Trane/AS use demand defrost. It has two sensors. A condenser coil sensor and an ambient temp sensor. It is constantly sensing the delta t between these two sensors. Once the calculated delta t is met, a defrost cycle is intiated.

Check the sensors. The coil sensor is located on the bottom of the coil, move it to the top and see if that remedies the issue. All sensors can be ohmed. Check the service manual for temp - resistance chart.

This is an open forum. We try not to get too technical here. Get your post count up and apply for a pro membership, then you can see what this site really has to offer.

[smoke]

Rain or undercharge.
If there are noncondensibles you will see an un-even frosting pattern across the whole coil.

~smoke~

[JMack13]

The OAT has not been below 34 & theres been no ice or anything on the house. The unit is on the eve end of the house so forget about water running off the house into it..& r glasgow, the top few rows of the coil are froze really big, not water freezing all across the top of the unit?

[JMack13]

& if it were non CONDENSEables would that not be in the top of the condenser?? Not causing problems in the evaporator right?

[JMack13]

Thanks for the input Brent..i'm trying to get my post count up! This is good info but still doesnt explain why it's freezing only at the top..

[Brent Ridley]

Jmack,

We can't diagnose the problem for you.

We can only offer "suggestions." It is very difficult to pinpoint a service issue such as this one from a keyboard.

You're a technician. Use yours skills, along with info provided and determine the issue. Let us know what you find!

[rglasgow]

Jmack, not sure of that particular coil but refrigerant does not generally enter from one end and exit the opposite end be it top or bottom. The coil has several different circuits. After completely defrosting, run in heat mode with no outdoor fan and observe for frosting pattern. May point you in the right direction.