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Re: central heat/air unit for home blows cold air
Replace your thermastat or if it is a replacement check your wires to make sure you have them right. Refer to the instruction manual for setting the heat anticipator and the cooling anticipator!
Red to Yellow calls for cooling
Red to White is usually calling for heat
Red to Green calls the Indoor Fan
Red to Orange is the call to a reversing valve on heat pump units!
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Sounds like the thermostat, the way to verify is to unplug indoor unit, remove thermostat, take pic of wiring with phone or label the wires as to the terminals. Carefully twist the yellow,(Y) Red (R) and the green (G) together. Plug the furnace back in, if the unit operates normally, replace the thermostat. I am basing this on the fact that the blower speed is changing. This could also be an anomaly within the circuit board in the furnace section, not likely though as the outside unit (condenser) is not controlled n by the indoor board unless this is a heat pump. hope this helps. D
If there is no cooling (meaning no cold pipes and not blowing cold air) then check the outdoor A/C for any visible/obvious issues; breakers not tripped, no debris blocking the outside unit from passing air through it, etc. If all looks ok, you can start checking some things inside of the unit if you feel comfortable doing so.
Also, most indoor heaters have a higher speed/rpm for the fan when the cooling kicks on, and the heat runs on a lower speed/rpm.
The inside fan will run while the unit is in defrost. The electric heat strips should kick on to help prevent you from feeling this cold air. When the unit is in defrost it is essentially running in the A/C mode. You should make sure the electric heat elements are working then go from there.
It sounds like the compressor is not coming on in the outside unit. If it worked fine and was cooling before, then your compressor probably over-heated and tripped the internal overload switch which causes it to stay off while everything else is working. The most common cause of your compressor over heating is an incorrect refrigerant charge, though it could be a few other things like a restriction in the copper line set. You will be able to hear the fan motor and the compressor kick on if you listen close while the system first turns on. If the compressor is over-heated, then after it cools to a save temperature, it will come on again, but only till it over-heats again. I would have the charge checked on the system, but remember that if the compressor is over-heated when the technician gets there, there is nothing he can do until it cools down and time is money! It's best to not run it until the problem gets figured out. Hope this helps and points you in the right direction. Good luck!
The blower motor kicks on when there has been a 24 volt control failure.
This usually means that a limit switch has tripped.
Most likely that would be a high temp limit switch or a rollout switch.
First, make sure the filters are clean. and the evap coil is clean. If eaither are dirty/clogged, it will partially block airflow, causing the furnace to overheat, causing the high temp limit to trip.
A rollout switch typically trips for three reasons.
1 flame rollout into the burner compartment due to poor airflow.
2 overheating af teh metal plate the rollout is mounted to, due to dirty, old, rusted components.
3 a bad limit switch.
If your unit has an LED light, count the flashes and it will hepl popint out the problem.
(locate the wiring diagram/flash code list, and correspond the flash count, with the code.)
Change your heating delay to shut off sooner, you can find this in the installation manual. Also the Thermostat may have delay after heat as well. It is true there could be many variables, but it also sounds like the Heatpump is not charged properly, you will have to have a different tech come out and check that. No need to have the installer mess your system up any further. This solution will only correct the auxilary heat, your heat pump on the other hand will require expert skills.
check the filter, make sure it's not plugged. Make sure all the vents are open. Are the lines freezing up (have ice on them?) Could be a lot of things but if it is not blowing much air then you may have a motor problem or dirty filter. If the unit is freezing up then probably have a leak and will need to be found, fixed and recharged.