Probably low air flow.

 

I didn’t actually check the cfm. But we did have a 20 degree difference across the evap.

 

Thanks for taking the time to read about my problem. I have a comfortmaker heat pump that I’ve been struggling with.

I'm curious as to the model number and refrigerant charge of this unit - can you provide them?

 

C4n36gkd200 factory charge 14.60 lbs

 

C4n36gkd200

Are you 100% sure of the model number? I don't recall any model with that nomenclature.

Maybe C4A3*** or C4A4****.

Do you have a picture of the data plate on the outdoor unit?

 

Guess that makes it a 3 Ton and not a 3 1/2 ton

 

How is the filter and indoor coil?

 

The filter is brand new. I inspected the coil. It is clean with no dirt or restrictions. Checked the TXV and it was not frosting. Inspected the TXV bulb and that is securely attached to the suction line. We had a 20 degree drop across the Evan when running. The system is 10 years old.

 

Did you try putting the TXV bulb in cold water then warm it to make sure it was opening and closing. It may be the valve is stuck wide open. All the refrigerant is in the evap with very little in the condenser. You may also have low air flow compounding the problem.

 

How long is the line set? Factory charge is only good for 15 feet. Any more than that and you need to add refrigerant and sometimes the indoor coil match-up requires more. Did you get the return wet bulb temperature?

There's a few possibilities of why you have low subcooling and superheat, more likely the sensing bulb is mounted improperly or the TXV is overfeeding. Low airflow is also a possibility, but I'd like to know the wet bulb temperature to see what your target split should be. 20 degrees isn't a standard.

I think it was overkill to pull out the charge to do a leak search. If you have to add more than 75% of the total charge, I would've advised the customer to do an electronic leak search first then nitrogen boost if necessary before dumping money on 15 pounds R410A. If they still want to recharge, UV dye is an option as well. If the system still has refrigerant in it, you should really only reserve a nitrogen test if a leak is suspected in the line set.

 

Not sure how to add a photo. Verified that is the model

 

What was your superheat and temp split before and after you weighed in the factory charge? Just out of curiosity when did you last calibrate your temperature clamps? How far is the coil from the condenser? What's your model number for your AH/furnace/evap coil? Need more info, somethings not right and possibly multiple somethings aren't right. Do a txv test as BNME8EZ said and take a amp draw. PHM has a really good checklist for anytime your checking a refrigerant circuit, get a copy and fill it out. Bet you the answer will be staring you in the face

 

Sounds like it could be a compressor issue. Compression ratio seems off adding refrigerant usually raises suction more than the head. Try pumping it down and watch your suction pressure some units do have a cut off at 30 psi to keep compressor from going into a vacuum. also high suction low head could be bypass in reversing valve but usually has high super heat.

 

I reread that and can't imagine a 3 ton unit holding 20 LBS of refrigerant. even a factory charge of 14 is high. Is it a very high efficiency with a giant circuit board in it cause you have to check pressures differently if it has an inverter board.

 

How about your return, what is the distance from the unit and what size you have ?

 

This unit is 9 years old and the first problem was when the unit was freezing up and was low on charge. Line set is probably 25 to 30 feet. I didn’t do any txv test because I was by myself and I’ve never done one of those. Everything worked fine on this unit until recently. Someone give me a link to this check list your mentioning. I could definitely use something like that. This unit just does not respond or behave like anything I’ve ever run across. I was thinking about something bypassing in reversing valve or something maybe but not sure how to check that. This unit ran great for 9 years and now is just doing something I’ve never seen. Talked to my supply house and they don’t have any ideas either. Ductwork has not changed. Lineset has not changed. Filter is brand new. Coils are clean. I’m going back again next Saturday so I’ll have to take the amp readings on the compressor and hopefully this check list you guys mentioned if I can get a copy

 

I am not sure about this check list, but here is a site you check out:

http://efficientcomfort.net/asp/ACanalyzer_Web/ACanalyzer_Web.asp

I hope that helps or at least heds you in the right direction.

 

From what I remember when we put the factory charge of 14lb in we were getting a 1.2 superheat. After we did everything else it never went above a 2. I think the highest we ever had the subcool was a 5 at one point and then that ended up as a 2 again. I don’t know if I’ll even be able to see the answer if it’s starting me in the face. I’m starting to understand a/c more but again I’m no expert. I’m trying to learn. I do nitrogen tests because I want to see if there’s any leaks. Im not interested in wasting a customers time trying to find tiny leaks in systems that are 10 or 20 years old. Seems a lot of the customers we have around my area report the same thing. Guys have come out for years trying to find and fix leaks in systems and they are paying huge prices every year for the same thing. I personally believe if you find 1 leak on a system that’s 10 years old there’s probably more coming. Everyone is going to disagree and I’m not interested in arguing that. I just want to fix the problem and get it resolved. That’s it.

 

Send me your email and I’ll send you the pictures of the nameplate

 

Unless you put your email in your profile, I can't email you mine.

If you access my profile, you can see my email address.

Please do not put your email in this thread.

I'm sure interested to see the name plate, as I have talked to a long time ICP rep (40 years) and he has never heard of that model number, nor can he find it in their computer system.

 

No inverter. Just a heat pump 9 years old. Nothing fancy. No crazy electronics inbit or anything like that. No communication boards or WiFi tstat. Just a simple heat pump. I might just call the comfortmaker rep out and tell him to figure it out or replace it under the warranty at this point.

 

Just a simple heat pump. I might just call the comfortmaker rep out and tell him to figure it out or replace it under the warranty at this point.

Doesn't work that way.

 

It doesn't seem from your readings after letting the house reach temp like the condenser is losing any heat so I'm wondering ifor you have a bad cap on the CFM or possibly the wrong motor. Is the condenser coil a double row coil that needs to be split to wash? It may only look clean from the outside. Secondly I have to wonder if the data plate maybe said it took 140 Oz and the 0 was just wiped off. 140 Oz comes out to 8.75#, which would make a lot more sense than 14# for a basic 3 ton split. Are you taking your lowside reading at the suction service valve or at the true suction port after the reversing valve?

 

Asking the guys at your parts house or trying to get a field rep out when you haven't stumped everyone at the factory tech support is a waste of time on the phone.

 

sounds like a 3m filter problem

 

3m filter, I was Tryan to know the return wall or ducting side but he didn’t answer, (with unit OFF mean defrost) by removing the filter for a little while I want to know if the frost up or not

 

It sounds like it's still low on refrigerant. The quantity seems high but the symptoms point to low. The terminology that you guys are using is different than what I'm used to so I apologize if I'm missing something here, but if I am following you correct then it sounds like the system is still thirsty. If the TXV doesn't have a full volume of liquid to it then it can't control the flow properly, it will always be hunting. At only 2 Deg subcooling, without knowing how or where you are taking your pressures and temperatures there is possibly some room for error here which means you may not actually have any subcooling at all. Are you wrapping your coil to your areas design temperature when you check the subcooling? If not you should be. Are you weighing the bottle before and after you add refrigerant without the gauges attached? If not you should be. If you have been leaving the gauges on then your quantities could be off, quite a bit off if you moved your gauges while charging.

It sounds like you didn't pressure test with a very high pressure. I've missed problematic leaks before because I didn't use a high enough pressure. Don't be afraid to bring it up to 600 on a 410a system. (Valve off the compressor and test it separately if it has a specific pressure rating, such as a Carlyle or some other cast body). If you have a blow off valve then make sure you don't go too close to the pressure rating of that either.

I would add more refrigerant until you get 8-10 Deg subcooling. Check your superheat as you go to make sure the TXV hasn't failed causing flood back.

If you have a high load on the house then it will dump a lot of refrigerant through the evap coil. Make sure you do your final checks and adjustments only once the coil is wrapped to bring your head up to the design temperature and the inside space temp has been brought into a normal temperature range. Is the TXV adjustable? if it is was it ever set correctly?

Out of curiosity how deep of a vacuum did you pull down to following your leak check?

Lastly, make sure the condenser coil is clean all the way through, as well as the evap coil. Looks can be deceiving if you are only looking at the surface of the coil. You have to forgive me, I'm not familiar with the model of your unit, is it a double layer coil? Is there a receiver? Remember you loose your subcooling when you go through a receiver so make sure you are checking your readings at the right spots and with accurate thermometers and gauges.

I'll leave it at that for tonight. I'll be curious to find out what you determine is the issue after you figure it out.



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Great response.

 

Is the compressor scroll or recip?

 

The unit cooled the house down to 70 it’s probably 85 outside. These are my readings 296psi high side, 95.8 lstat, 93.6 line temp, 2.3 subcool. 140.6psi low side, 50.1 vstat, 51.3 line temp, 1.2 superheat. 20degree delta tee across the return and supply.

I may have missed something somewhere, but all that looks like an overfeeding TXV. 50˚ saturated suction pretty much eliminates low airflow, particularly for 70˚ return.

Anytime you see 1˚ superheat with a TXV, something's not right with the valve function. :.02: