I suspect that I might have a problem with our heat pump. It is collecting ice. It isn't thick and it doesn't cover all of the outside coils, but it doesn't seem to be going away like it is supposed to. If I run it in AC mode it will get rid of the ice.

Any thoughts and what it might cost?

Does it look like this?  If so you are screwed!!!!  

no it's only half that far out from the unit.....

Tag

you are not supposed to use a heat pump below a certain outdoor temperature - my controller can take a temperature input to prevent using it when below like 40degF and switch to gas heat

Possible low on refrigerant charge, by switching to ac reverses the position of the evaporator and condenser by reversing valve that’s why the ice melts when you switch to ac.  I don’t know what ac service people charge in your area for repairs.  Any way I would have your heat pump looked at soon.

Quoted: you are not supposed to use a heat pump below a certain outdoor temperature - my controller can take a temperature input to prevent using it when below like 40degF and switch to gas heat

Yeah, but any salesman will tell you a heat pump is good down to 0 degrees, which is B.S, and that it's controlled by a bimetal switch located at the condenser which cannot be adjusted.

I switch my thermostat over to gas only @~ 40 to 50 degrees just because it blows colder air than I like and it won't wear it out as fast by cycling on and off.

Your unit is not going through it's defrost mode or not completely.

Call a serviceman, bend over, hope for the best.  

you should have a defrost switch or control in your outside unit to switch your reversing valve and bring on emergency heat, be it electric or gas. i would suspect that is where your problem lies. what kind of temps. are you running this heatpump?

its normal to have a thin layer of ice kinda like you get on your windsheild on a frosty morning. even if seems to always have it, because if its cold out it will emediatly frost back up a little minutes after it defrosts . if it looks like a snow ball that tells you it is not defrosting at all, and you have 1 of 2 problems. its either your defrost board or your outdoor bimetal is bad.

Mine gets a very thin layer of frost/ice on it, and always has down below 30 degrees (it's set to kick over to gas at 25 degrees), but it's done that for 8 years. I figured it was normal.

Mine did the same thing.  I called a repairman and he replaced some small part with a couple of long red wires.  He charged me $80 for the part and $100 for the service call.  The year before it was some other part that cost me about $200 (including service call).  Bottom line, be prepared to pay about $200 to get the problem fixed.

There are generally two parts that control the deice depending on the age of the heat pump.

Older units had a timer switch that had a thermo bulb device attached in the condenser coils, it's a bulb about the diamenter of a pencil with a thin copper tube attached and it goes to the timer located inside the contactor panel of the heat pump.

Newer units 20 years & later have an electronic de-ice controller, ICM make a replacement, if I recall the p/n is ICM-300. Along with a de-ice thermo switch. The switch is attached to one of the tubes on the condenser. It will have two wires attached that go back to the controller board. One or the other is likely bad. You can use an ohmeter to check the switch. Should have the temp rating marked on it, IIRC, it will measure open above ~30deg and closed below ~30deg. You place it in your freezer to test it. If it checks o.k., then it's likely the timer board. I've had to replace both at differnt times in my heat pump over the years. Replaced one in the heat pump at work.

If all this is over your head electrically, then don't DIY. Call a professional and you'll at least have an idea of what's wrong & know if they are ripping you off or not. HTH