Carrier Model 58DXT - Blower Speed Adjust. - http://www.hvacmechanic.com/ Forums

Original message

snek

171.71.92.126

"Carrier Model 58DXT - Blower Speed Adjust." , posted Mon 14 Jul 11:11

My Home has a Carrier Weathermaker 8000 model 58DXT080-16 Furnace w/ AC coil. The unit was recently reinstalled as part
of a remodel. The unit heated the house fine last winter - but
cooling is not performing as it should. The cooling air temp drop out of the unit is around 8-11 degrees - which I am happy with. The think the problem is that the blower is running on the low speed (its a 2 speed sys) when cooling. When it was reinstalled - a new thermostat which supported 2 speed heating
was installed (a single speed thermo was installed perviously)
Does anyonme know if there is a variable blower speed adjustment on the controller for this furnace or what the wiring diagram for the thermostat terminals are so I can check my install. I want to make sure that this is corerect before I haul off and consider replacing the unit. - Many thanks in advance! Ken

Replies:

theduke03

24.250.18.179

"Re(1):Carrier Model 58DXT - Blower Speed Adj" , posted Mon 14 Jul 16:47

Your problem is not the blower speed, which should not have been touched, or changed during stat replacement or re-installation of furnace. The problem is with the a/c system, could be several things, low charge, dirty condenser, or open/broken attic ducts. You can inspect any attic return ducts and hose out the coil on outdoor unit good.
If coil is clean and ducts are intact and problem persists then it's most likely low on charge and you will need a pro.

"My dad was the most feared furnace fighter in Northern Indiana."

snek

171.71.92.126

"Re(2):Carrier Model 58DXT - Blower Speed Adj" , posted Mon 14 Jul 17:00

Thanks 'Duke'....

So - During the re-install - both valves at the condensor were
replaced as well, system was charged, Lower ducting was redone (all ducting was new as of 2000), and additional cold return was added and all ducting replaced w/ larger size to ensure enough air return. The system heated the house well in winter and I noticed that there was alot more airflow during heating than there is now from AC. Prior to remodel - AC blower output
was much stronger.

So - it could be open ducting on return side - I will check. I
will also hose down condesor coils tonight.

I also want to rewire the thermostat to single blower speed - do you know which terminals on the controller control the 2 blower speeds? I think this may be improperly wired between thermostat and furnace controller. Thanks!

theduke03

24.250.18.179

"Re(3):Carrier Model 58DXT - Blower Speed Adj" , posted Mon 14 Jul 17:18:

The thermostat does not control the blower speed, that is accomplished by the circuitboard in the furnace. There is no way to do what you propose, and like I said, those speeds should not have been changed. It is possible that your indoor coil is freezing up and blocking airflow. If you don't believe me then open up the furnace and look at the circuitboard. If a black wire is on the COOL terminal then it's already on high speed.
Have you checked your filter?

"My dad was the most feared furnace fighter in Northern Indiana."

[this message was edited by theduke03 on Mon 14 Jul 17:19]