A/C just not cooling adequately

[sbayliss01]

Hi guys. I am at a loss with my own heatpump. Heres the run down. I have a coleman 12 seer 4 ton heatpump, 7/8 suction line 3/8 liquid, 42 feet of linset, R-22 system which holds 11.8#'s. Connected to and intertherm indoor AHU mod# B2BM-a048. So heres the problem. My suction pressure is 115 psig and my discharge is 300psig. The ambient temperature here today is 120 degrees F. 16% humidity, indoor ambient of the house is 83 F. Discharge air temp in the house is only 71.2. The duct work is in good condition filters, and coils clean indoor and out. I checked the orfice on the AHU factory was an 85. I changed to 80 trying to increase head and lower suction no luck. With the ambient temps out side my head pressure should be around 350-375. suction of about 75 I am not even close. Tested the suction valves on the compressor by pumping it down into itself they seem fine I feel that it may be a discharge valve problem? I also checked the Reversing valve operation seems fine no noticable bleed by that I can see. Also changed indoor fan speed from high to medium nothing changed.:rolleyes: Any suggestion?

[billdozza]

how many square feet of space is this unit trying to cool.

[sbayliss01]

1400 sqft. stucco home

[sbayliss01]

Also, i had a new reversing valve, so to eliminate any chance of bleed by I went ahead and changed this morning, as of right now it is 114 outside and still the same results. high suction (115 psig) Head pressure of 275. It almost feels like I am flooding back, suction line is cold to the touch, discharge line extremely hot. Suction line temperature 12 inches from compressor reads 76 degrees. 115psig=65 degrees. 76-65=11 degrees superheat. Dishcharge air temp at the condenser is 124 degrees. 124 discharge temp -114 ambient 10 degrees of heat. Maybe I've been in the heat to long and I am missing the obvious. Not enough heat absorbtion from the indoor coil. Should I ditch the piston and install a TXV? I dont know.

[momo]

Some older R22 units start doing weird things like icing back to the compressor but still not cooling enough (not blocked filters etc) ... There are threads on this topic. Without prejudice and expecting a storm... My analysis is that the compressor ceases to work effectively and "we" put more gas in to get the system to do what we expect, but: it won't suck enough and push enough: hence hot discharge and lack of pressure difference. Usually (in Europe) when a system starts to show these symptoms I recommend a new one on R410. (They are mostly splits which are cheaper than a repair and not the cost of a US duct system) Unfortunately if the customer has tight pockets that is the end of the story! (Until I use the binoculars to see what someone else has done!!)

[paul_h]

Did you just say you soldered in a new reversing valve?
You did it right and kept the valve doused in a wet rag to stop it getting too hot right?

115psi is 790kpa suction, that has to be a stuffed compressor if the valve was changed correctly unless it's full of air.
Unless there's a huge overcharge to make up for a restriction somewhere Strainer, drier capilary etc)

This is a critically charged system right, with a weighed charge on the label and the charge in the system has been verified by reclaiming, weighing?
After reclaim open up all strainers, distributors, capilaries and clean (even if it a strainer needs to be sweated off on the indoor - I learnt the hard way), visually check and blow through with nitrogen, or directly clean. Then change LL drier, give it a deep evac and charge with virgin refrigerant, that's the full proceedure.

Though thats after checking temps and operation over the 4 way valve to make sure that's not the fault.

A lot of work, but the thing to do and only worth it when the only alternative is writing off the whole system or compressor.