[p2pcoach]

Hello all. I certainly have found a TON of info on this site, and problems that sound just like mine, but solutions seem to point to different things than in my system. So I apologize in advance if this is a duplicate somebody already answered.

I have an older Ducane Oil Furnace converted to GFA. Back before I knew anything, I bought a LUX 500 programmable TSTAT and installed it, and it has worked fine for the past 3 years. This year during our nice spring, I turned the system off, as we did not need heat, or cooling, and opened the windows. About 2 weeks later, I wanted to turn the a/c on. Switched the tstat to call for cool - nothing. Here's what I have so far:
Checked the barrel fuses at the (Bryant) compressor - good.
Checked breakers at the box - good.
Checked the inline circuit fuse inside the furnace which is connected to Honeywell R8325A contactor block/relay - good (and switched on).

My dad had a 'friend' in the business - disconnected all the wires, which I did not take pictures of before-hand :mad:, and system did not work, and now I have been trying to reconnect them for 2 weeks.

Here's where I currently am stuck:

When a call for heat is made, furnace operates normally (connections may be right - may not be)
When a call for cool is made (after waiting 3 minutes after switching to cool on TSTAT), compressor turns on, blower does not. When I turn the fan limiter (rotate) on, blower comes on.?

What I don't understand is - why all of the components work, just no fan when the A/C turns on when a call for cooling is made.

Wiring is as follows:
TSTAT has 4 wires R, W, G, B
Red (Rh & Rc jumpered) is connected to R on contactor/relay block (Honeywell R8325A)
White is wired to Red wire on millivolt gas valve wire
Green is wired to G
Blue is wired to Y

Gas Valve (Honeywell millivolt (V 800 A 1005)) wired as follows:
Red wire to white wire on TSTAT
White wire to W on contactor relay

A/C wires (from Bryant Compressor) wired as follows:
Red to C on contactor
White to Y on contactor

Tested capacitor yesterday in Bryant unit - seems to rise and fall as it is charged and discharged (checked with fluke meter vac ond ohms)

I have taken some pictures and linked them here - I am unsure what to do - am I missing a jumper wire from the cooling lead to fan?

Not sure what pictures might be necessary so here is a link to some I have taken with explanations on some of them.

<table style="width:194px;"><tr><td align="center" style="height:194px;background:url(http://picasaweb.google.com/s/c/tran...background.gif) no-repeat left"><a href="http://picasaweb.google.com/P2PCoach/D4Furnace?feat=embedwebsite"><img src="http://lh5.ggpht.com/_8TGxN-gRhro/SjU3tpU2T1E/AAAAAAAAABw/l4KcIZQF9I0/s160-c/D4Furnace.jpg" width="160" height="160" style="margin:1px 0 0 4px;"></a></td></tr><tr><td style="text-align:center;font-family:arial,sans-serif;font-size:11px"><a href="http://picasaweb.google.com/P2PCoach/D4Furnace?feat=embedwebsite" style="color:#4D4D4D;font-weight:bold;text-decoration:none;">D4|\/| Furnace</a></td></tr></table>

Any help will be GREATLY appreciated. My wife will love having a/c again.

[Joshdta]

Sounds like your fan center relay has went bad. Pull the little white botton on the fan limit intill you get one and you should have ac the rest of the weekend.

[p2pcoach]

Thank for the fast reply! I'll try that. Here is the accurate link to the pictures. Picasa Web Albums - P2PCoach - D4|\/| Furnace

[Joshdta]

Well from your pictures I see you donn't have a manual fan on botton on the limit. This could also be your t-stat. Jump from r to g at the stat and see if the fan runs

[p2pcoach]

I tried jumping the R (Rh & Rc jumpered) & G terminals (at the stat) and the fan did not come on. That's the part I am having the hardest time understanding. When I turn the dial (clockwise) on the fan limit (at the furnace) the fan comes on, and then goes off as soon as I let off.

[p2pcoach]

If I were to pull off all of the wires, and put them back on, what is the best way, do you suppose to wire it? I have 4 from the stat,
Red,Green,White,Blue;
2 from the A/c - Red and White.
And 2 from the Gas Valve - Red and white

Which wire would go to which terminal?

[hvac1000]

There should be a relay in that black fan center.

[hvac1000]

PS the dial you are turning is only designed to work in the heat mode not in AC. Stop turning the dial manually or you will stretch the BI-METAL and that will be the next item you will be replacing in the heating season.

[p2pcoach]

Thanks. There is a relay, and I hear it engage (loud click) when I energize the circuit. Is there supposed to be something else?

I would be surprised if something were missing, as everything was working fine last fall when we still used a/c, and then all through the winter. We switched the stat to heat, everything okay all through the winter. When we went to switch the stat to cool, this spring, that's when stuff stopped working. Then the wires got pulled off the contactor. And here we are...
Sorry I was unaware of the fan limit spring stretching.

Is it possible that there is another relay in the compressor that is bad - does it possibly control the blower inside? Just a question.

If that relay that engages when the circuit is energized, is it possible that the contactor block is bad? Maybe the wires in back are wired incorrectly... those haven't changed since last year.

Is there a way to bypass the contactor block to temporarily get a/c until this is resolved? My wife is going crazy, and I insist on fixing this, as it seems simple, yet not easy.

[hvac1000]

I pointed you in the correct direction to start your search for your unit problem which is in the picture of yours I posted back to you. You seem to have a low voltage problem or a relay that is defective. Just because something clicks does not mean it is working corectly. Thake your meter and check that relay for proper operation. The indoor unit HAS to have a relay to control the blower motor in the A/C mode. This is where you need to start. I agree your problem is simple in nature but to the uninformed it could be a complex issue and difficult to understand.

There is a generic wiring diagram for fan control centers in the link below. It might not look like yours but they are all just about the same. Good luck with your adventure.

http://www.white-rodgers.com/wrdhom/.../0037-5786.pdf

[p2pcoach]

Thank for the diagram and assistance. I was just taking voltage measurements when you were replying.
Here's what I got:

R - G 0 vac
R - C 26.6 vac
C - W 20 vac
C - Y 20 vac
C - G 26.6 vac

Initially I thought if the c and g terminals had that voltage, the blower would start. What I am tending to believe is that there is voltage across the c terminal, and that g is grounding somewhere - maybe the coil is bad or has deteriorated.

When I was downstairs, I wired up just the R and G with the stat set to fan on (temp switch set to cool). If I connected just the r and g, I should have had the fan running, shouldn't I? Or does it also require the common, which I believe would be white. Right?

Which leaves me thinking that I need to replace the contactor / relay? I had this apart last week to inspect, and all looked clean, unwelded, and unobstructed, with no spiders etc. I did think that since I heard the click of the relay, that it was working maybe even correctly. I am unaware of what else there may be internally to start the fan.

Theory: If I connected the Green wire to the R or C, the fan will run, if the contactor block is operating correctly.

It's 12:45 a.m. here, I am retiring for the evening. Hopefully I can figure out what to do tomorrow.