Heat Pumps and Electric Heating - One big block of ice

My heat was working fine - no problems. I went to leave and as I drove off I noticed that my entire Lennox heat pump was covered in ice. When I got home I switched to emergency heat, but it is still covered in ice. Whats the problem? I suspect the defrost stage is not functioning properly. Any help?

Defrost failure most likely, If this is a later model unit it will be like working on the blamed space shuttle, not much a DIYer can do without factory service info. Call your favorite tech that services the Lennox line he can fix you right up for a fee, hopefully a nominal fee. Parts prices are to high to just start swapping parts. Unless of course you have a truck loaded with known good ones and sometimes that is sadly exactly what it boils down to, a tech with matching parts can dang sure fix it in a few minutes LOL.

Is this something that has to be repaired right away or can this wait for a few weeks (after the holidays)?

seanb ,
i agree with dnt1 that the defrost control board may be deepsixing.
or it could be the defrost temperature switch (hopefully, it's cheaper).
if you want to wait until the holidays are done, you will be using the heat strips at the air handler. that will make the power bill higher. if that is your choice, disconnect the power source to to the heat pump so you don't kill it.

barry

I feel your pain, seanb. I have a Rheem SEER 13 that would have made a good ice machine, 600 bucks worth of service that didn't stick until Rheem changed the defrost board design.

If you've experienced temps 30-40 and high humidity, the defrost cycle may be working but be unable to keep your outdoor coil free of ice. To check it I'd do this;

Turn your thermostat to OFF, and turn off the circuit breaker that powers your outdoor unit. Do not proceed unless you are certain there is no power to the outdoor unit.
Open the electrical cover of your outdoor unit.
Locate the wire that powers the outdoor fan, (it should be on a relay), and safely disconnect it. If you can't locate it you probably need to call a service company to handle the repair/de-icing.

If you've located it and can turn the circuit breaker back on, the thermostat to HEAT, and the thermostat to above room temperature, and you can go out and verify that the compressor is running, and the fan is not, you are good to continue.

Turn the thermostat to OFF position, and the dial to 15-20 degrees below room temperature.

At this point you should find some old blankets, furniture moving blankets work really well, and cover the outdoor unit. You are now going to run the heat pump as an AC, taking indoor heat and pumping it through the outdoor coil to defrost it. Go back to the thermostat and turn it to AC. Go back outdoors and confirm that the compressor is running. Go back inside and keep your coat on, it's going to get chilly. Check periodically and see if the unit starts deicing and dripping. If so, wait it out until the coil is free of ice, turn the thermostat to OFF, then turn the circuit breaker off again, reconnect the fan lead, remove the blankets and turn on the breaker and set the thermostat to HEAT, desired room temperature, and see if the compressor and fan turn back on. If they do and the unit doesn't ice up in the next couple of days, maybe your defrost board and sensors are OK. I live in the midwest and have to do this two to three times a winter just because of the humidity.

To check it I'd do this;

Turn your thermostat to OFF, and turn off the circuit breaker that powers your outdoor unit. Do not proceed unless you are certain there is no power to the outdoor unit.
Open the electrical cover of your outdoor unit.
Locate the wire that powers the outdoor fan, (it should be on a relay), and safely disconnect it. If you can't locate it you probably need to call a service company to handle the repair/de-icing.

If you've located it and can turn the circuit breaker back on, the thermostat to HEAT, and the thermostat to above room temperature, and you can go out and verify that the compressor is running, and the fan is not, you are good to continue.

Turn the thermostat to OFF position, and the dial to 15-20 degrees below room temperature.

At this point you should find some old blankets, furniture moving blankets work really well, and cover the outdoor unit. You are now going to run the heat pump as an AC, taking indoor heat and pumping it through the outdoor coil to defrost it. Go back to the thermostat and turn it to AC. Go back outdoors and confirm that the compressor is running. Go back inside and keep your coat on, it's going to get chilly. Check periodically and see if the unit starts deicing and dripping. If so, wait it out until the coil is free of ice, turn the thermostat to OFF, then turn the circuit breaker off again, reconnect the fan lead, remove the blankets and turn on the breaker and set the thermostat to HEAT, desired room temperature, and see if the compressor and fan turn back on. If they do and the unit doesn't ice up in the next couple of days, maybe your defrost board and sensors are OK. I live in the midwest and have to do this two to three times a winter just because of the humidity.

Or you could just run water out of the hose over it till the ice melts.

Yeah, Shank, I was going to suggest hooking a hose to the drain port of his water heater and melting the ice with that, but it's cold here in the midwest, no-one still has a hose hooked up, and I don't know seanbs' level of expertise, and electricity and water aren't a good combination.

If he hasn't already called a service company he's at least assured of more options.

:)