Need heat pump help

Ok - so trying to diagnose the issue with our heat pump - and it’s got me perplexed.

Initially thermostat (digital) quits working on Sunday in middle of an 85 degree day - took 30 minutes to figure it was the heat pump and not thermostat failure.

Check everything over - no idea why it’s not working. Swap out filter (slightly dirty) - kicks right on.

Next day - same issue - take out filter, put back in - kicks on. Ok - maybe I didn’t get it in right or had it upside down. 4 hours later - same issue.

So now I’m thinking low refrigerant - the unit is 21 years old - and if that’s it…time to just replace it. Call HVAC guy - he’s out at least a week.

Let it recover an hour and remove the filter - slip it back in - works fine. I’m thinking - ok, I’m gonna have to limp this thing along for a week till new unit arrives. Just letting it kick off when it loses pressure - rest and rebuild them restart it.

Funny thing is - today has been by far hottest day yet and nothing - humming right along.

Now given the unit is old enough to legally drink - I think it’s overdue to be replaced - but why is it doing this ? Any thoughts - malfunction of some sort of sensor measuring air flow? Seems like it’s very sensitive to filters to me - in my unprofessional opinion.

And any idea on cost of fair replacement for a 3 ton unit - quoted 4700-5500 earlier for a 14 seer unit. My regular guy was right in middle at 5200 - seem right?

 

Check your voltage at the disconnect when everything is running on the hottest part of the day. If voltage is below 210, the compressor can trip internally on overload. Then will reset about 4-6 hrs later. Also you could have bad connection or breaker, check the outdoor fan, if the compressor is running it should be too. If you are uncomfortable about checking the electrical call a tech. A good tech can figure it out. As far as replacement cost, it more about the make of the unit. Most units with a 5 year warranty average replacement cost are between $4,000- $6,000. The high end units with a 10 year warranty can be between $6,000-$8,000. Before you buy, get a second quote.

 

Might be moisture building up on the coil and freezing over. Check for clogged drains and check the evaporative coil for icing over.

 

Yes.

 

I’m not 100% - but icing was a thought as well.

Funny thing is - changed first filter, worked fine…for a day. Took out filter and flipped - worked 3 hours, took it back out and changed with another new filter (same type/model but new batch) has worked fine for last 3 days - no issues.

Checked with regular guy - price up to 5700 (forgot to add a few things - and small price increase on unit). I’m torn - replace now or wait - I mean it’s running fine and it’s been hotter last 3 days than before - and more humid. At same time if I wait - it’s likely to fail completely on a long weekend or be a 3 week wait on new unit I’m sure.

I mean it’s 21 years old - but I’m cheap. Probably just need to suck it up and count my blessings it will likely make it till new unit can be installed.

edit to add - replacement is a Carrier - entry level with 10 year warranty. I had a few quotes before - but like this local company best. Might check one other to get an idea on price - but can’t see it being that much cheaper.

 

I think the dirty filter reduced airflow and caused icing over. Doubt you need immediate replacement, however use a water hose and gently wash the condenser out being careful not to bend the fins, just another maintenance item to make sure you have efficiency and good longevity.

 

Your txv could also be going out, slight chance since you said unit was turning off completely but I have seen faulty valves on brand new units that weirdly kick unit off when trying to adjust. This could also be looked at and replaced by a pro. At 21 years, it's like replacing a small part on a vehicle that has had little to no maintenance for 21 years, your going to end up pouring money into it trying to keep it going. Much better to get that Carrier unit in and have piece of mind for the next 10 years.

 

21 years old.....time to replace it. I did the same on mine every year it was 500, then 300. and so on.

 

Sometimes it is easier for some folks to pay a few hundred bucks now and again vs throwing down five or eight grand and maybe paying interest. For example I have been running a few appliances for about 20 years, yeah maybe a bearing, motor, seal, etc. now and again, but I don't have to scrap the chassis, the wiring, the housings, etc. Plus it keeps me from digging into savings or paying any interest. On top of that, you can teach others how to repair a dryer, dishwasher, oven, furnace, grill, washing machine, disposer, etc. I mean kids need to learn how to survive during the hard times. So, if money can be saved, someone can be educated, and the environmental impact can be reduced, then cool, get out the tools.

 

Might be a control board problem or you could have a refrigerant leak. I just replaced my 25 yr old upstairs Carrier Heat Pump control board. The unit would run fine and then cycle, reset electrical at the panel and runs fine again for a while and cycle. Control board was like $35.

On my downstairs unit I had a leak in my evaporator coil and it was freezing up. My home warranty picked up the tab for that.