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-   -   Inside Fan not working (http://www.diychatroom.com/f17/inside-fan-not-working-23219/)

BenH 07-05-2008 08:16 PM

Inside Fan not working
 
Ok, please forgive me first off. I'm starting to learn this whole HVAC thing. So if i sound stupid well...........

The inside fan motor on my goodman unit has started to act up. It works every now and again with no ryme or reason to it. When it does stop working it causes the outside unit and the inside coils to freeze up. I had a guy come check freon level and it's ok, but since the fan was working when he was here, he could not find anything wrong.

So now it's pretty much stopped working all together.

I do know that it is a 220v motor. It has 3 wires ( one is not used ,only for low speed). I have a purple ( which is connected to one leg of 220 service ) and a brown ( which apears to be connected to a relay ).

Now if I measure each wire with my fluke i get 120v each, but together nothing. Since i know the pruple is a straight shot to the hot line, the proplem is in the brown wire. :(

If I remove the brown wire from the relay, and plug it into a empty spade on the hot termial the fan kicks in and runs fine. ( So I know the fan is ok ). :thumbsup:

What i don't know is if the relay is not working or is the DIgital stat not outputing voltage to trigger said relay???????????????:censored:

The stat is a 7 dat low volage Honeywell. It appears to be outputting around 9-11v on the trigger wire for the realy, is this a normal voltage level? If so, I guess my problem is in the relay.

Any help would be awesome!!!!!!!:thumbup:

wirenut1110 07-05-2008 10:42 PM

Not sure how your checking the voltage but you should have 24 volts to the relay. If you're comfortable with it take a jumper and jump R & G and see if it comes on. At your air handler, check to see if you have 24 volts going to the stat on red and coming back on green.

biggles 07-06-2008 09:15 AM

does the fan run from just a FAN/ON from the stat with system switched off on the subbase...your right on the relay being the problem.if your in auto fan and cooling and the relay is acting up their could be a drain thru the stat causing that relay to act up causing the fan to stop in the cooling cycle.leave the fan in the on position during the cooling and see if the relay acts up and you get ice...if it happens change the relay.if your reading 24V at the relay coil the fan should be running in auto or fan on

Sammy 07-06-2008 12:44 PM

I aint no HVAC guy but just went thru the same thing on my air handler.

Goodman/Janitrol are known for having issues with the fan relay.


Went thru the same thing of coils clogging up, no problems when tech was here etc. [first tech fell thru the ceiling but thats a whole other story]

I got the unit to come on by setting the tstat to fan "on" til the tech could get back and it worked fine.

Test the relay if you can get it to duplicate the problem. If not, just replace it for 20 bucks or so.

BenH 07-06-2008 02:29 PM

Quote:

Originally Posted by wirenut1110 (Post 136373)
Not sure how your checking the voltage but you should have 24 volts to the relay. If you're comfortable with it take a jumper and jump R & G and see if it comes on. At your air handler, check to see if you have 24 volts going to the stat on red and coming back on green.

Thanks guys, I love this forum, just a bunch of smart good people. :thumbup:

Just another question, do you mean measure to ground ( the chasis of the unit ) and see if the stat is inputing/outputing 24v?

wirenut1110 07-06-2008 02:37 PM

Some kind of ground, or at the txfr itself. If your only getting 11 volts, that relay isn't going to work. Could just have a bad wire. If that's the case, hopefully they pulled t-stat wire that has spares in it. It does sound like your relay, just depends on if it's getting 24 volts. As was asked, did you try the fan ON switch to see if that worked?

BenH 07-06-2008 03:10 PM

Quote:

Originally Posted by wirenut1110 (Post 136536)
Some kind of ground, or at the txfr itself. If your only getting 11 volts, that relay isn't going to work. Could just have a bad wire. If that's the case, hopefully they pulled t-stat wire that has spares in it. It does sound like your relay, just depends on if it's getting 24 volts. As was asked, did you try the fan ON switch to see if that worked?

The fan DID work on the ON position for a few times (still erratic), but even now that doesn't make it come on all the time. In my mind thats seems to be another finger to point at the relay.

Forgive me, but what is txfr??:huh:

I guess I could check continuity on both red and green wires (the stat is pretty close to the main board)

As far as the relay goes, which wire is the feed and which is the trigger? and does it ground through the mounting point?

wirenut1110 07-06-2008 03:24 PM

It's the transformer, check at the air handler where the relay is and see if you have 24 volts. A relay is just a switch using 24 volts to switch 120 or 240 power. Green and common The red wire leaves the airhandler with 24 volts on it, the t-stat just switches that 24 volts to make whatever run for fan it's the green, the green wire energizes the relay coil to switch the normally open contacts to close. checking continuity will be fine, as I said, it's just a switch so you should read little or no resistance. It could very well be the relay but I'd make sure, there's alot of replacement mechanics out there that don't troubleshoot, they just replace it till they get it right. If you have a constant 24 volts to the relay and it's intermittent then it's the relay, if the voltage fluctuates then you have another issue.

BenH 07-06-2008 04:09 PM

Just my luck, I put the black wire back to the relay contact and the fan kicks in as mornal (makes it hard to jumper wire test the relay when it;s working).:mad:

However, i did retest the red and green wire on the stat wires and with my prob to ground to the chasis of the indoor unit, I'm still reading 9.75V/AC on both wires???? Keep in mind everything is working normal at the moment. No jumpers, or wires moved:huh:

BenH 07-06-2008 04:23 PM

Ok i found the trfx, and if I measure with the output wires connected i get 9.75 at the spade, but if i unplug the wire (no load) i get 23.56vac.

But, the fan just quite again and If I jump the output of the txfx and the green wire of the relay the fan does NOT come on.

wirenut1110 07-06-2008 04:25 PM

Is it blowing cold air? Is it a heat pump? Sounds like you have something pulling that voltage down. I've had a bad reversing valve coil pull the voltage down thought it was a bad txfr and later found the reversing valve coil smoked. IF I recall correctly, the coil is energized in cooling.

BenH 07-06-2008 04:28 PM

yes and yes on both questions.

wirenut1110 07-06-2008 04:31 PM

that relay could have a bad coil pulling the voltage down we should've just listened to biggles I just like to make sure

BenH 07-06-2008 04:37 PM

I'll try to pick up and new relay on Monday and I'll check back with a report. Thanks again wirenut, and everyone else.

Tonight I'll just leave the fan jumped to hot so I can atleast have a/c.

biggles 07-06-2008 07:30 PM

tell us what your secondary VOLTS are off the furnace TR that supplies the whole show it has to be 24 or better (test right off the first wire nuts off it unit running and in the off position.if your reading 24V at the coil for the relay for the fan and it is not consistant in running the fan change the relay but lets see that main control voltage right out of the TR.:whistling2:


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