Fan reduced over summer by contractor; Now heating fan is so low, heat barely works
I live in Phoenix. Over the summer, I had some water dripping from the air handler in the attic, causing a wet spot on the drywall below it. Short story is contractor (sent by warranty co.) determined it was water blowing from drip tray into ductwork due to powerful airflow over drip tray and no baffle to stop it. He said that since parts aren't available for the circa 1993 unit he would simply drop fan speed to 1/2, preventing blowing of water and enabling it to drain out (drain was clear). AC worked, still, but didn't cool the house as fast as it had been able to before. They sent three different guys (first guy thought it was a sweating cold refrigerant pipe, which it wasn't), and I finally gave up on worrying about it, as the leak stopped.
Now, it's winter, and we've had some record cold (for Phoenix) with lows in the mid to high 20's. Cold enough to freeze my water pipes in the early AM! The problem is the gas heat system has been struggling to warm the house. The fan speed appears to be very low -- about 1/2 that of the already lowered AC speed, and if memory serves, about 1/2 of what the heat formerly was last winter season. It's so quiet I hardly hear it, and I barely feel flow when it's on. When it runs, the areas of the house away from the thermostat, which is in the hallway by the bedrooms, is frequently much colder than the main living area, which finally does seem to get a bit warmer, but only after a long time of running. During the nights in the upper 20's, it was really cold in the bedrooms, where almost no airflow came out of the ceiling-mounted ducts. I have a feeling the heat just stayed near the ceiling.
I called the warranty co. and they spoke with the HVAC company that they work with, who agreed to send their "senior tech", who is here now. He turns out to be one of the same guys who had come originally in the summer and thought the freon tube was sweating. He is telling me that the fan has to be lower or else it will cause the heater core to crack due to condensation or getting too hot (I didn't know condensation was an issue with a heating core).
In case anyone wants to read the summer thread, here it is: http://hvac-talk.com/vbb/showthread....his-assessment
Thanks for the input!
That "senior tech" has it backward. Not enough airflow can cause a heat exchanger to become too hot, potentially cracking it.
Your problem overall may be airflow related, frequently caused by poor duct installation. Could have contributed to last summer's condensation problem.
Home warranty companies...no comment other than good luck finding someone who really understands HVAC and will shoot straight with you and the insurance company. Doesn't happen all that often, in my experience.
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.
I would recommend you bite the bullet and pay out of pocket for a different company to come out. Your described symptoms don't match the "senior tech" diagnosis.
OK. I just finished talking to the tech. He showed me a photo of the AC coil, which was apparently very dirty. After the 4th visit they finally took a look at that. I asked him why no one checked it the first, second and third visits, and he said that since the system was cooling well, there wasn't a reason to suspect a dirty coil (and noted that, if the coil had been seen to be dirty, a replacement compressor, which I got last year, wouldn't have been approved).
The tech showed me that the Goodman air handler wiring was properly set -- the "Low" wire was set to Heat, the "Medium" wire to AC, and the "High" was set to Park (this was done by the tech last year to prevent the water splashing out of the tray).
He explained that the clogged coil is causing the unit to get too hot, tripping the overheat switch and shutting it off. I was up there with him and it happened while I was watching -- the unit shut off and the flames stopped (he thinks I might want to replace that overheat switch too since it's been activated quite a bit recently). He says the coil is mounted sideways for some reason and can't easily be accessed, so the cleaning procedure would require it to be cut out and resoldered, with all the freon being recaptured before hand (he mentioned how expensive R22 is now -- $$ a pound, really?), total cost $$-$$$ to 900 dollars, more than he feels that 2005-era Goodman unit is worth.
I asked him if I could raise the heat fan speed to medium by swapping the wires. He said he couldn't do it for obvious reasons but told me how I could do it and thought it might help prevent the overheat situation.
I don't know how long I will stay in this house, and my summer AC bills have been pretty good for Phoenix standards, so I'm not sure I am ready to invest $$$$ into the new system.
Thanks for any input!!! I appreciate it.
Last edited by beenthere; 01-19-2013 at 04:07 PM.
Welcome to the world of home warrany companies.
It's not if your doing it right it's whether your doing the right thing that is important.
Have the coil pulled and cleaned. A 2005 goodman unit should have ability to trap the freon in the outside unit for repair and then release it back.
You should recoup a decent amount back in lowered gas bills as well as being more comfortable.
No one has addressed the filtering problems that caused the coil to get like this.
Thanks for all the replies. He told me that it would cost $$$ to $$$ to pull the coil due to the need to cut it out. He thought it might be possible to trap the freon. But he thought it wasn't worth putting money into what he thought was a cheap Goodman unit...
Last edited by jpsmith1cm; 01-19-2013 at 07:25 PM.
Originally Posted by toocoolforschool
Experience is a hard teacher because she gives the test first, the lesson afterwards". -Vernon Law-
"Never let success go to your head, and never let failure go to your heart". - Unknown
"To face tragedy is the greatest challenge; to overcome tragedy is the greatest success" -Ranal Currie-
They should have spotted that the coil was dirty when they changed the compressor. Good chance that is what killed the compressor.
Originally Posted by sshanky
X2, but airflow is often overlooked.
Originally Posted by beenthere