Reply to Thread

It's nice to see your rep doing something about the issue. I believe the coleman issue is an oversized distribution manifold and a longer coil section where the sensor is mounted. The oversized distribution manifold promotes a lackluster flow and I believe oil collects in the longer loop where the sensor is also located and basically chokes it off during defrost.

There's probably not enough restriction to affect cooling, although the condition still exists.

Thus wasn’t a one off issue either. When I talked to the FSR and told him about the temperature variation across the different coil sections he was pretty sure what the problem was and where. It was at the CU/AL tube connection on the spine fin. The odd part was it didn’t seem to be a problem when cooling. It was a known issue but no bulletins on it.

I suspect oil stagnation might be playing an issue on the coleman, but all (that I've encountered) of the hc8 3 and 4 ton and variants have the same issue. So in this case, it's not a one off problem unfortunately.

Not a Coleman unit but I had a Trane unit that the tubing for the coil didn’t get reamed correctly so over time oil built up in that section and it would not get warm enough. Ended up replacing the coil.

Proper charge won't help with specifically the Coleman "hc8b" 3 and 4 ton units (and variants). No matter what the charge, the coil loop that has the coil sensor clamped to it cannot get hot enough to melt the ice during defrost. The other coil loops will run 40⁰f hotter during defrost. The heat pump defrost operation will either time out or shut off on the high head pressure switch before the faulty loop will defrost. The result is long, unnecessary defrost cycles and a hard layer of thick clear ice on the faulty loop. You can lengthen the defrost cycle with jumper settings, but keep in mind, that this heat pump will continuously defrost for the full duration no matter what the conditions, one ice is present on the coil. There is no official fix for the issue. The long and unnecessary defrost cycles takes it's toll on this unit as outdoor coil and compressor failures will occur. The head pressure near the end of all the unnecessary defrost cycles is usually above 550psi.

He's kinda right. Weighed in charge is good if lineset is 10ft. Otherwise charge like you normally do. HP needs to be dialed in right to avoid issues in heating mode. Cooling mode is forgiving

Whiskey Tango Foxtrot !!!

Originally Posted by bruced

What is your sub-cooling? Weighed charges wont do it!

W T F ?

For all finding this thread; this is a flaw with this model of heat pump, specially the 3 and 4 ton 18 seer 2 stage. The coleman model number is hc8b. York has an identical version. The issue is; the outdoor coil can't pass enough heat to the section of the coil that has the sensor clamped to it. If you think you are smart and you move the sensor, then the faulty section of the coil will become a hard section of clear ice that will eventually create a leak. There is no official fix to this date. It's a design flaw.

Thanks for all the replies. I called tech support and the guy I was talking to said I should check the charge. So What I ended up doing was adding some more gas to the system to get the discharge temperature up around 170F in defrost mode. What I also did was speed the indoor fan up some. The reason for that was because I checked the speed on electric heat and it was low compare to the flashes I was getting on the board. Knock on wood haven't heard anything back yet.

Originally Posted by dgunt

I have a customer that has a Coleman 18SEER 2 Stage 3Ton heat pump. The issue that I am having with the unit is that it wouldn't defrost the bottom 1/4 of the coil. The unit is sitting up on a snow stand that is 18" off the ground. I have weighed the charge out and re-weighed the correct charge back into the system. I have switched the defrost board on it. I have checked the defrost sensor to see if it was out of range (ohms out fine). What I notice when I was there last time was that the top part of the coil would heat up to 110F and the bottom part had a hard time getting up to 80F after 10mins in defrost. Has anyone had defrost issues with the Coleman or York 18SEER units?? Also I have check the reversing valve to see if it was leaking by and there is only a 1F difference between in and out on the suction side in heating and defrost mode.

I remember reading a post from Mr. DigiCool that this problem ( with UPG equipment) is common in your area. I would contact Coleman....

SUB-COOLING

What is your sub-cooling? Weighed charges wont do it!

Might call Tech Support, see if they recommend relocating sensor. I recall a manufacturer doing that back some time ago, but I don't remember who,,,,,,,,solved the problem on that one.

In heat pump mode is the discharge line temp 125 plus outdoor ambient?

If you're satisfied the system is running right, and if the bottom quarter is ice (instead of frost), have you tried "manually" removing the ice with water, assuming it ain't 15˚ ambient? It may have just gotten behind for whatever reason.

Coleman H/P Defrost Issues

I have a customer that has a Coleman 18SEER 2 Stage 3Ton heat pump. The issue that I am having with the unit is that it wouldn't defrost the bottom 1/4 of the coil. The unit is sitting up on a snow stand that is 18" off the ground. I have weighed the charge out and re-weighed the correct charge back into the system. I have switched the defrost board on it. I have checked the defrost sensor to see if it was out of range (ohms out fine). What I notice when I was there last time was that the top part of the coil would heat up to 110F and the bottom part had a hard time getting up to 80F after 10mins in defrost. Has anyone had defrost issues with the Coleman or York 18SEER units?? Also I have check the reversing valve to see if it was leaking by and there is only a 1F difference between in and out on the suction side in heating and defrost mode.