I have a Carrier infinity system that is ~ 8 years old and has been fine until this year. it has been cleaned regularly. We have been through a BRUTAL cold snap the last 3-4 weeks. I will say we have gotten his cold previously but not for this length of time that I recall. To cut to the chase My concern / question is the amount of ice build up in the bottom pan I can't say for sure how thick it is but I would guess 1/4 to 1". It is below the coils. I am not sure if this is normal and if not how does one deice the pan? A bit more information follows.

The first problem noted was a pulsating noise when going into defrost. loud enough to be heard in the house.
The installer sent a service guy out. he checked the pressures and all seemed well. It went into defrost and the noise appeared.
He noted if he placed pressure on a front corner he could clearly feel the pulsing.
The unit had a fair amount of ice under and inside it with some frozen on the ground.
Raising the noisy corner seemed to help it a lot. It only made the noise one time after that and raising the same corner eliminated it again. I believe the unit may have been frozen the the stands and pan which was transmitting the noise.
A week or so went by and the unit threw a code 83 low pressure lock out. it was -10 or so.
Once it got back into the 20's I pulled the side panels and verified all was clean. The outermost drip holes were partially blocked so they were cleaned. There was a small amount of ice an some surface of the lower coils, not a lot or very thick, maybe an inch or so high in some areas. Again fairly small areas overall
using warm water and alcohol was able to get the lowest portion of the pan below the coils completely de iced and open.

The unit ran for about 2 hours and threw the code again. Temps have been as high as 25 with no change. We are running on backup electric heat and the installer is BURIED due to the unusual temps.

thanks for any input assistance

WAG: Partially stuck reversing valve. Try unplugging it to see if that helps. Be careful when working around electricity especially on wet ground.

thanks for the reply. Supposed to be getting into mid to high 30's this week, So I hope to get the ice out of the pan. Resetting it as suggested will likely work but I'd prefer to isolate and fix the issue before the next artic blast which may not be until next year. the unit has never done this before so i suspect something is amiss
Thanks again for responding
What does WAG: mean

Also be aware that there is a good size capacitor in there that can kill you even when the power is disconnected from the unit.

WAG = "Wild A$$ed Guess"

Using your Carrier model number search the internet, eBay and Amazon for a copy of the specific service manual.

At a certain outside temperature the efficiency of an air heat pump is so low that your hourly electric bill is equal to just using resistance heaters.

I would guess even for your 8 year old higher efficiency air heat pump
the “break even” outside air temperature is 25 degrees F plus/minus 4 degrees.

Thanks for the responses, I reset the unit today ( power on /power off). Code went away but then several things transpired that are totally whacky like the display saying the heat pumps running when it's not. HP and electric heat running when raising the t/sat by 1 degree, HP pump occasionally would run but slowly, then the Code popped up again. So have to wait until they come out. At least we have the electric back up
Note the outside temp

I needed a system reset on my Mitsubishi top of the line multi zone and they said the temperature had to be above 50 for the reset to work. What a bunch of s---h. Buy a unit that says it'll work to -15 which it does and produces heat @ 115 degrees but can't run long enough to produce enough heat without having to defrost. I've had it several years and to be honest once it's zero it's pretty much worthless. Mike

this units been fine for 8 years, only locked out once at -28. This time it's a whacking out. Service tech scheduled for Thursday afternoon

My new heat pump cooled fine in the summer but would not run on heat. At first it would trip on high pressure, then it would constantly trip on low pressure. Put the gauges on it and pressures were good in cooling but would drop to almost zero in heat mode.

Ended up being a bad heating side expansion valve. Mine is adjustable, and by fully exercising the adjustment screw, got it to work for about 30 minutes then same thing. Had to change it. My stupid 4 ton heat pump (top of the line 2 stage crap) takes 20 lbs of R410A!

Yeah I see on your picture that your unit switches to electric heat once it gets too cold. Almost all whole house units have that feature. Most people don't even notice. The only way to know it happened is when you look at the readout and the red electric heat light is on. The heat pump shuts off at a certain temp and runs 100% as an electric heater. My split mini doesn't have that feature. Good luck Mike

thanks,
Tomorrow is D-day and i will be really interested to see what they come up with. I will not be surprised if there is more than 1 issue asthis fiasco started several weeeks back and has displayed a myriad of symptoms the most common and consistent being the same fault code I'll keep you guys updated.
Thanks to all again

Tech was out today, System was completely empty The muffler off the compressor had cracked well above the solder joint which he said was quite strange. So might be next week before he can get the replacement installed

Wow that's quite a surprise. Gee without the backup electric you would have been 100% without heat.

In your first post you mentioned noise and vibration, plus pushing down on a corner changing them.

That vibration should be a suspect in the root cause of the muffler crack.

Tuesday Wall Stree Journal on page A3 has article
“Heat Pumps Get Trial Runs in Bitter Cold”.

sample quote

Standard Heat Pumps operate efficiently at Outdoor temperatures down to 35 degrees F,
but newer cold weather systems can operate down to 7 degrees
- and engineers are pushing heat pumps to go further.”

end quote

Long article then goes on to explain that these more expensive new heat pump systems have frequency changing inverter driven variable speed AND double stage compressors.

These newest air exchange heat pump systems cost in the $7500 range
but the US Federal government currently has a $2000 tax rebate for the most efficient systems.

Ground coupled air pumps cost about $11,000 more.

Rheem is mentioned as a manufacturer aggressively competing to be the “winner” of annual DOE testing,
but the picture in the article shows a Mitsubishi.

It really is pretty impressive what they're able to do now.



https://www.mitsubishicomfort.com/blog/mythbusters-heat-pumps-for-extreme-cold-climates

The cold side expansion gets, well, cold. Depending on the heat pump, it's around -40F. If the air temperature is -5F, that's still 35 degrees of heat that it can capture and move inside.

I have a H2I and yeah it operates in the cold down to -15 but the problem is they can only run about 15 minutes below 0 before they go back to defrost for at least 10 minutes so they can't keep up. I checked it the other day @ 40 and it was producing heat at 115 well above the average of 55 over temp which would = 95.

I am sure they would have put a priority on it were that the case. I don't know that anyone would use a heat pump as their sole source of heat If so pretty gutsy IMO. I could have also used the oil filled radiant heaters that I already have for the shop and the fireplace.

Agreed, it may have been an indicator of things to come We only lifted very lightly on the one corner and the noise stopped. It came back about 2 hours later. Again a light "bumping" of the same corner stopped it altogether. The unit ran for at least 7-10 days before throwing the first code. But is was -25 when it did so which I'm told is not unusual. once things warmed up to -10 or so, I reset the unit it rans for about two hours and started wigging out.
The latest is the part is on order from carrier and hoped to be installed later this week or early next.
meanwhile our temps are in the 40's & 50's

Yea, the defrost cycles don't help. It might have been the other thread I posted a video. In it, he says the three most important things when it comes to heat pumps (and other heat sources too) is:
1. Insulation.
2. Insulation.
3. Insulation.



But really, if you live somewhere where it's routinely below 0F for long stretches, an air source heat pump probably isn't the best idea. But for 50 hours overnight over a couple weeks during a polar vortex? They're probably good enough.

I found an "Insulation 2.0" thing on youtube, about removing attic insulation, air sealing any gaps & cracks to the house below, then blowing insulation back in. I found and fixed a couple holes here, and am already noticing a difference.