Repair or Replace 5 ton system

4 days ago

Hi all. Thanks in advance for any help or thoughts. I have a repair vs replace decision to make. My house has 3 compressors/air handlers (5, 4, 3 tons respectively). 3 weeks ago I noticed that the upstairs (5 ton) system had stopped cooling. I poked my head into the attic - the condensate drain had become clogged, the overflow pan filled, and the float switch had shut the outdoor compressor unit down. I had been pouring bleach/water in it regularly but I guess it wasn’t enough. This has happened once before. Different this time - the blower fan was still running (but not the outdoor compressor). I waited an hour for it to stop but it did not, so I shut the breaker off. I drained the overflow pan and opened the access panels to the air handler guts. The coils were clean, but there was evidence of water throughout the unit. I did notice that the main circuit board looked corroded, and that it was in an area where it probably got wet whenever the unit overflowed with water. I put it all back together. I turned the breaker back on and heard the outdoor compressor turn on and assumed the unit was back to normal. The unit ran as normal (I thought) through a hot summer day. Later that day I noticed that while the compressor was running, the fan was not – air was not moving. I tried adjusting the thermostats to ‘cool’ and to ‘fan’ but nothing would make the blower click on. I made an appointment for an HVAC tech to come out the next day and went off to sleep in the basement. The tech came the next day and after poking around said the circuit board was bad. It took a few days but he came back with a replacement. After replacing the board the unit came back on normally (blower and compressor) but the air was not cool. He hooked up his equipment to the compressor and told me the refrigerant was very low and that I must have a leak now. He added some refrigerant and the air coming out of the vents turned cold. Within two days it was back to being just a little cool again (not cold enough to cool the house in daytime). Same tech came back out, added a ‘leak fixer’ and some more refrigerant and told me he doubted it would fix it but was worth a try. Same result – within one day the air was cool but not cold.

Background: The house has been remodeled since the attic air handler was installed, and the opening left for access is not big enough to get the old air handler out or a new one in. Any replacement of the handler or the coils will either require serious carpentry to the house or disassembly and reassembly of the replacement and old unit.

I bought the house 6 years ago. In the documentation is a receipt for the replacement of the 5 ton compressor and new coil in 2011. The unit worked great up until 3 weeks ago. Compressor is model Goodman ssx160591aa; coil is CHPF4860D6; air handler is MVBC2000AA-1AC. I had a lot of work done on the attic ducting / zoning three years ago and I am pretty sure the coil was disconnected / reconnected during that, if that matters.

I suspect something happened to the coil or its connections during the above drain overflow events – maybe it froze solid and something shifted(?) I am thinking of asking for two sets of quotes – one for an isolation test and how much to replace the coil if that is in fact the issue, and another quote to replace the whole 5 ton system.

If you told me I would get 5 years out of a repaired (replaced coil) system, I would lean towards the repair. First, I think it avoids the carpentry issue. Second, the other two units (4 ton and 3 ton) are both r22 and I know I am going to need to do something eventually. I have had a ton of insulating work done over the past few years and suspect I don’t need this much cooling, but would like to approach a complete retool in a thoughtful manner, not in the middle of a Summer of lockdown with a grumpy hot family.

Any thoughts or advice would be greatly appreciated. Thank you.

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