I live in a 1200 sq. ft. mobile home in South Texas - HOT and HUMID. Last month I had my condenser and evaporator coils replaced. The compressor was shot. Since it was an 18 y/o 10 SEER Coleman I had both replaced. The original system was a 3.5 ton unit. The replacement is a 3.5 ton unit (13 SEER) and the evaporator coil is rated 10 SEER with a TXV. I replaced the thermostat with a digital one.
The previous unit had to strain to keep the house at 85 when the temp passed 95. We get broadside sun from 3:00 pm on.
The new unit works great. It has been over 100 for 2 weeks straight and will keep the temp around 76 (unless my wife is cooking and then the temp goes to 85 - way better than the old unit). It runs long enough to dehumidify well. I have a digital weather center and the indoor humidity is usually around 25 - 30 %.
The e-coils have been freezing most nights around 3 am. The technician has been out 3 times to check everything out. The last time (last Friday) I probed for answers harder than usual. He said the condenser split was good and the pressures are right where they should be (thus the TXV was working). The temp right where the air enters the blower read 74 and the nearest vent read 56. This was when my wife cooking. The digital thermostat read 83. His digital thermometer read 78 when placed next to the thermostat. It was pretty uncomfortable because the humidity was up from cooking (open floor plan where kitchen and living room are open). He said the air flow was good and the ducts are not restricting air flow. He said trying to get to 70 degrees at night is the issue. Since there is no load on the system because of the cooler night temp, the e-coils freeze the condensate instead of the water draining into the pain.
He suggested setting the thermostat to 74 and see if that solved the issue. Tonight the temp was 74 and the coils froze again.
This technician has serviced my a/c for over 5 years and is extremely honest. He is also spoke at several conferences, so he's knowledgeable. During the last visit he did mention servicing mobile homes isn't his main source of business so he was going to talk to the regional experts. I haven't heard back, but I will definitely be talking to him today.
Could this be because the e-coils are rated for 10 SEER instead of 13 SEER? Does all of this ice put a strain on the new condenser (Ruud 13AJA R22)
I know I've rambled, but getting up at 3 am kind of fogs my brain and I've been doing it a lot lately.
I'm not a DIYer. I can't afford to have everything done twice. I do software, not a/c.
Thanks for your help and opinions.