I know there are a few heat and air guys here and was hoping to point me in the right direction. I don't have anything to service it with but I like to know before someone looks at it and tries to convince me it needs a new unit. I have two identical AC units, about 5 feet apart, that service upstairs and downstairs. My guess is low refrigerant but I'm no pro and haven't put gauges on it. I have an auto set but didn't want to blow anything up if the pressures are higher. It looks like it should be 450psi and 250psi on this label. The downstairs unit seems to not be cooling as well. It cools but it runs longer and the air doesn't feel as cool as it used to. I've checked the usual, clogged condenser, fresh filter and the fan is turning freely when not on. The return air is 75 and outlet air nearest the unit is 64. When I checked the upstairs, it is hotter but the return is 78 and outlet is 68 though it has only been running for about 5 minutes. Also, I checked the outside high and low pipes at the valve fittings. Ambient temp is 96. The downstairs has shorter runs of pipe but they were much closer together after running well over 30 minutes. They were high 98 and low 82. The upstairs has a full story of extra tubing and it showed a wider difference in temps. High side was 107 and the low was 74. Thoughts or recommendations? I'm going to call someone shortly but I don't assume they can get to it before next week. With an upstairs unit, we will survive without much discomfort. Here's a pic on the side of the unit. April 2013?
When my refrigerant gets low the indoor coil freezes up. It happens about every 3 years. It's running Puron (410A). Are you getting good air flow from the vents? Filter is clean?
It is a 410A system. Got a guy, owns an old Chevy pickup truck and comes to the cruises on Tuesday night. He is a former boss's neighbor. Filter was not clogged, getting good air flow and coils weren't iced over. It wasn't sufficiently cool though was the issue. First, my bad. The condenser coils were dirty. Second, the system was exactly 1 lb of refrigerant low. $128 later, it is cooling nice and he cleaned the coils on the upstairs unit as well. Cheap enough!
That 1Lbs makes all the difference, the extreme is when the coils freeze up. Its a great diagnosis, but not the norm when temperatures on are the threshold of the units cooling capacity. Glad it was kinda cheap to fix.
You and me both. It would cool to 77 and not a degree cooler. When it was 80 at midnight, it was running all the time. The first time I realized there was a problem was when the kitchen floor in front of the vent was no longer so cold.
410A normal operating pressures should be around 125 - 150 on the low side and 325 - 400 on the high. It will fluctuate depending on Amb air temp in and out. Basic rule of thumb is a 15 - 20* temp differential across the coil. So say 75 going in the return should be 55 coming out the plenum with a 10* loss by the time it gets out of the vents. You paid close to what my normal rate would be for a service call and 1 lb of 410.
Be sure your evaporator and condenser coils are clean. You should be cleaning them once a year and replacing/cleaning the filters monthly.
I have a filter timer. I replace the filter every 300 hours. The outside coils I've never cleaned but I had been cleaning the leaves out the fan compartment every year. My other AC unit at the garage is clean so I didn't think about these ones being dirty. There is only a metal grate around the other one. These are fully enclosed and you have to be low and look up to see them.
Good reminder - I need to clean my condenser. I run the system's circulation fan 24/7/365. Keeps the entire house's temp much more consistent room to room and I have to change filters more often which I'm happy to do - Less dust in the house.
In a lot of systems, the filter is not well sealed, so air can leak in and contaminate the evaporator. I purchased a commercial building, this air handler was in a closet and the filter was mounted in the door. There was a 1/2" gap under the door where air could leak in. The evaporator was so bad it couldn't be cleaned, not with compressed air, a vacuum cleaner, nothing, I had to replace the unit. In my house, I have the filter and the duct work going from the filter to the air handler totally sealed, I even put foam adhesive weather stripping where the filter seats so no air can leak around it. If air is not flowing through the evaporator properly, the refrigerant may not expand and can go back to the compressor as liquid and "slug" the compressor which can damage it. I like your idea of letting the fan run, I wish they made a system that runs the fan at 1/3 speed when the compressor isn't running.
I like your idea of letting the fan run, I wish they made a system that runs the fan at 1/3 speed when the compressor isn't running.[/QUOTE] they do make a cont run fan motor. when you replace your furnace opt for a true dc variable speed blower motor. the upcharge worth every single penny!
Good point on the evaporator & sealing the filter. The airflow sucks the filter against the housing but not sure my housing is really all that... I can't remember why I started running the fan 100% of the time (IIRC was to try and even out the temps as our t-stst is not in a great location) & I have no idea & not sure I want to know what it costs in electricity but the benefits have been great. Will definitely look @ the VS DC motor. ⅓ or even ½ speed would probably achieve the same results.
My return is very short, less than 10 feet. I sealed it up when moved in many years ago and that was several years before the new system was installed.
