Have HVAC Questions? Ask an HVAC Expert for Answers
Hello and thanks for using this service, if you have been waiting do not worry or get upset I am just one of the techs on here and I try to get to as many customers as I can and I just picked up your question now. Please give me time to respond sometimes I get your replies late so there may be a delay in my response.
If the fan is running the A coil may be iced up can you check that?
In the furnace plenum or airhandler it is the coil that coils and heats.....it may be iced over
OK well then the airhandler is not running, that could be a lot of things, can you get at the airhandler unit to see if any error codes are flashing on the board?
Can you locate your indoor unit for me and tell me if it is a gas furnace or an electric air handler? If electric there should be a label on front listing model number.get me that number and we will go from there.
Excellent.Thanks for that information.Let me see if I have a manual so I can help with accurate information.I do not want to throw out a guess or just tell you it could be many things.I want to help you find the problem.
While I am looking for a manual. there should be 2 panels on front. One will be where the cooling coil is (you will see the copper lines ). The other,usually top is where blower is. Our first step is to open that top panel and turn thermostat to heat or coil and see if the indoor blower runs.Also see if there is any ice on the copper pipes or coil.
This top panel
Once you have top panel removed and thermostat on, be careful not to stick your hand in blower, but take a flashlight and look in and tell me if the blower wheel is turning.
OK. Next let me know if you have a multi meter for troubleshooting?
I am suspecting we either have a bad fan motor or a bad capacitor, but throwing out a guess without troubleshooting properly would be less than professional and not much of an expert.. With unit calling for heat or cool we want to check between FAN COM and FAN SPEED terminals on the air handler control board to see if motor is getting 230 volts.See drawing below
Absolutely.Let me know if you see the control board and the terminals marked FAN COM and FAN SPEED. That is where we want to check for voltage.
Remind him we are working with high voltage, then with thermostat calling for cool or heat check between those terminals by putting one lead on each and meter set to AC Voltage lowest scale above 240 (Probably will be 600V on meter)
Excellent set to 400v and check for 230 to 240 between FAN COM and FAN SPEED
1. You can pull wires out of you want. Remember to turn power off first and when wires can not touch metal, turn back on and check between wires (not terminals on board).
2. Lets's check this first.Fuse is a possibility but not as likely since you have a hummimg.
LOL. My bad. I told you to check wires, We need to check terminals since wires are unplugged.
What are e getting? Also check from each of those terminals to ground on cabinet
Do not let wires touch metal when they have voltage on them. We are going to put a meter lead to metal ground and a meter lead to each of the FAN SPEED and FAN COM to see what we have on each leg.
No power on and calling for heat every time
Something mot jiving there. The two terminals receive power from the two legs of a 230v double pole breaker.Are you sure meter is set correctly and good batteries? We should not be getting more than about 125 volts max from one leg od the breaker.(One terminal)
If meter is set correctly and good batteries lets do same thing at the actual breaker that supplies voltage to air handler.(In main power panel)
I am not understanding . Where did you get the 194 and 44.5?
I am still confused. You said you put the multi meter on those terminals and then you said you did not put a muli meter on it but used a meter with a bulb.Help me understand.
Excellent now at breaker the 244 is good. Lets go each leg to ground in panel
Excellent.Thanks for clearing that up. Now lets go back to air hander and locate the power wires coming into unit and do same. Check between them and then each leg to ground.
Not making good sense on our power. If we have 120.5 from a leg of breaker to ground at breaker, We should have that same 120.5 at unit on that leg
We should have steady power pretty much, maybe fluxuating a few volts, but no way we should have 230v to ground from a breaker that is sending 120.5 to ground.Wondering if there is an issue with meter.
Get rid of the light tester. If will not work for what we are doing.We want to be at the very first lugs where power comes to furnace and using the meter right now. Can you send pictures showing what you are doing?
If you have a paper clip icon on your page you can attach using that link.Or
You can upload the pictures using the tiny pic site .
Here is a link to the site.
Click on Browse , select the file from your folder.then click UPLOAD NOW.
They will give you a quote to enter in the box to verify you are a human.Enter the quote and click UPLOAD NOW
You will see your picture on right side of screen.
Then copy the link URL for email & IM
Paste that link here on the site.
I am about to have to leave so I am going to open this to other experts so you do not have to wait.
Hi, I'm Tim and I'm an HVAC expert here to help answer your question(s). Please provide all the information I ask for since I'm not onsite. At the end of our dialog you will be asked to rate my service, but please wait until then and all your question(s) have been answered satisfactorily. If you are not satisfied, I'd appreciate it if you'd tell me why before leaving a negative rating and allow me to continue to work with you until we are able to both agree on an outcome to follow. Thanks for your business!
You say the indoor unit is "humming". Can you open up blower panel, find the blower wheel, and try to spin it with power off. Let me know what you find.