Stumped on blower

Hey guys,

I'm trying to trouble shoot my A/C system. I installed a new ritetemp thermostat awhile back during the winter. All has been well. I trying A/C yesterday for the first time and here is what happens-
Outside unit starts right up. Blower does not come on. Set fan to "on" position on thermostat and fan still does not run. Turn heat back on as a test and blower operates perfectly. I tried jumping the green blower wire to the "RC" wire to bypass the thermostat and still no blower. I traced back the thermostat control wires and everything appears correctly wired on both the thermostat and on the A/C unit.
The system is an older York. It has what seems like a transformer and a small printed circuit board that connects to the thermostat.
Any ideas? Please! Its 93 degrees today.

Interestingly I found another online with the same exact problem-
"I have purchased a new digitial Thermostat for this. When I turn the switch to Heat, Auto,, The Blower works and heat is produced. When I try to go Cold, The Compressor outside starts working, Cooling water gets to the Condenser but the Blower motor never turns ON. I have my 24Volts present on the Furnance control but the Fan does not turn on. Not even when I change setting to ON Vs Auto."

Thanks,
Necktie

 

Fan don't work with t-stat fan switch to ON?

G at t-stat is wired G at the furnace?

If G is wired up at both spot with same color wire, then take a small wire/jumper and touch R and G at the furnace, fan should run.. If it don't, then it either can be the fan relay, or the cooling speed on the furnace is not working.

 

Hi Jay,

Thanks for your response.
Fan does not work unless I turn on the heat. In the Fan "ON" position nothing happens.
Green is connected to to G at the furnace and the stat. I jumped R and G at both the stat and again at the furnace with no response. I have 24v at the stat.
Would the fan relay only affect AC and not heat? Just trying to narrow it down as the wait for a AC tech may be several weeks...

Best,
Necktie

 

Yes, if the fan relay is not working, the fan won't work...

Heating speed of the blower is controlled by the fan/limit switch. (Lower speed)

What is the make/model of the furnace?

Take a photo of the control area if you can?

 

Its a pretty old unit from York. The model is N2aHD10A06E. I'll try to take a photo tomorrow, its a pretty tight squeeze between the boiler and air handler.
The unit has a small circuit board with a relay and a transformer with a 24v secondary. The transformer felt slightly warm to the touch after having left the stat in the "on" position for several hours.

Thnaks again.

Necktie

 

If you must need A/C, see if there a peg or wire the blower to a 110v source, and by doing that, the blower will run non-stop.

I was not able to find that model, so will be waiting for the photo.

 

Good idea Jay. I can do a simple hook up to 110V with an in line switch to power it on and off as a temporary measure or just plug it in and out as needed.
This blower might be 15 or 20 years old at this point. It was in the house when we moved in and we know the the condensor is from 1992. The motor itself looks very clean and was probably changed at some point.

 

Here is a quick photo of the unit-http://homepage.mac.com/jhalpern/Pics/PhotoAlbum43.html

 

Looks like that board is an "add on"???

Take a good photo of the wire diagram that's under the board.

 

Anything is possible in this house. Check the same link for some attempts at taking a photo of the schematic.

Thanks!

 

Forget the cheating... Your blower is 220v system.

That relay, there a blue and black wire going to the relay. That may be your problem.

I see only one speed is being used..., and you said you have blower in heat mode....

can you do a better shot on the other diagram? (elementary)

 

Okay, new photo should be up in a few minutes with hopefully a better shot of the elementary. I also found the installation instructions in our files for this unit if that is helpful.

 

Humm.. The photo is not working?? I see the thumbnail, I click on that, and the larger screen comes up, but blank.. If I hit the next or prev, I see those photo, not the one you posted this morning.

 

Weird. I just redid it and its working for me now... let me know if its working for you.

 

ok, I now see it, but the low voltage side is cut off.. I think it's has to do with the low voltage, and not the relay like I thought.

Does the install manual have this diagram like this?

 

I ordered an exact replacement of the circuit board with relay just in case and it'll be here tomorrow.
The manual doesn't have the diagram or I'd scan it. Let me try another picture, I'll have it up in five minutes or so.

 

I don't see W hook up???

Keep us posted on the new board.

 

a lot of those york units control fan speed thru the board. They will run high speed for heat and med or whatever it is set to for cooling. I would replace the board if it is reasonably priced.

 

How about moving the blue wire from the relay to NC vice NO.

THis will let the fan run 24/7 and take the relay out of the picture for now.

Diagram shows blower on high only.

I'm looking at pic DSC00962.

 

I'll give that a shot. 24/7 is okay with me for now. I'll have the new board in the AM at $23.00 so that will hopefully resolve it. Can't imagine what else it could be.

Necktie

 

Okay- dropped in the new circuit board with relay and no luck. Blower still working with heat but not A/C. Is there a relay on the condensor unit side of things that could cuase the problem? What makes no sense is why putting green directly to RC dos not start the blower... something else must be in the electrical path...
I'll try the 24?7 thing next.

Necktie

 

Where are you getting RC at? I didn't see it on the wire diagram..

Does all the t-stat wire go to this board? What letters are on the board? (Y. G. W...ect)

 

Hi Jay,

The red wire that comes from the circuit board goes to the 24v transformer. It then makes a connection to a thin black wire which you can see in the photo. This black wire is connected to the thermostats RC connection. A wiring mistake at the thermostat is a strong possibility so let me know if this seems wrong.

Thanks!

 

Okay- moved the wire on the relay and we have 24/7 blower operation. I now have A/C!! Its a great short term solution. Now to try to understand why this is happening... Does this shed any light as to what the problem may be?

 

ok, I think I found your problem!

On the transformer, should be letter stamped on it. From what I can see on the right side, the R on top, and C below.

R from that (red wire) should go to R on the board, and R to t-stat.

C from that(black wire) to C on the board. and a wire to the unit outside. From what I can see in the photo, that black wire is on the upper left side of transformer.

G from that (blue wire) to G on the board, and G to the t-stat. ( see a green wire hanging lose in the photo, is that an extra wire from outside?

 

Okay- the extra green wire you see is from a harness that goes to the boiler from the furnace. Its disconnected at both ends. It appears to be an extra control wire that is unused.

C on the transformer is connected to a wire that comes from outside- I assume the condensor. It is white in color for reference and connected at the transformer's bottom right corner in the photo.

R is connected to R on the transformer, R on the circuit board and R at the stat. The wire from the stat happens to be black in color but its correctly wired. The wire is red to the circuit board.

G is all correctly wired to G at the stat, G on the transformer and G on the circuit board. Its the blue wire to the circuit board's G marking.

The thicker black wire on the transformer is connected to C on the circuit board. No other wire is connected to this transformer tap.

Regards,
Necktie

 

Ok, move that thick black wire down to C on transformer. Right now That wire is tied to nothing like you said.

 

Any update for us here?

 

Hi Jay,

I've been distracted by some other work related things, sorry. I have not yet moved the wires but will do so later today and report back. When we came to see this house efore purchasing, the A/C was working well. We closed in September and had no need for A/C until a few days ago. It seems odd that someone would rewire the A/C wrongly between August and September... anything is possible.

Necktie

 

Tried moving the wire to C. Switched the relay connection back to normal. No dice. Still no blower when fan is switched to on and when A/C is on. Back to manual control with the breaker(S).

Necktie

 

Leave that wire on C as I'd suggest, then take a jumper wire between R and G at the transformer, nothing, then try R and G on the board.