Thanks in advance for any advice this forum can offer. Our system has
been blowing heat tremendously all winter long, but now that spring
and humidity are here we have no A/C. The outside fan is not turning,
but the pilot light in the furnace unit in our garage is on and air is
blowing out of the vents. No circuit breakers are tripped.
Here are the system details:
- The garage unit is a Rheem RCBA-3765AS17
- The outside A/C unit is a Rheem Classic X High Efficiency
- The thermostat is a Hunter 44360 that I installed this past fall
after the original unit failed
I have posted some photos of these units at Flickr in case anything
shows up that could be useful to an expert:
I am assuming that the outside unit not spinning is the root of the
problem. If there's some DIY aspect to this, I'd be thrilled, as I've
paid a lot of home repair bills lately and would love to save some
cash. At the same time, if it's something that an amateur shouldn't
tackle, then I won't.
Thank You daytona
For once I get to say it and mean it.
"Replace the thermostat. Its almost always the thermostat (installer)"
Now, lets point out a few things according to your post.
1) The heat worked all winter long
2) Spring came around and No A/C to be found
3) The outside fan is not turning
4) The pilot lite in the furnace is on (not that I really care)
5) Air is blowing out of the vents (I guess thats why the heat worked)
6) No circuit breakers are tripped
7) The thermostat is a Hunter(Eww, I going to take one brownie point
away for that)
**NOW here comes the key point so PAY ATTENTION!**
8) When did YOU say that YOU replaced your thermostat?
9) Why did your A/C work last year?
Are you sure you've found and checked ALL of the breakers.
Most systems are fitted with one more breaker than can
be found on a routine inspection ;-)
The outside unit most likely contains two main parts.
The fan which you say is not turning. There's also
a compressor. Is that running? You should be able to
hear it while standing by the unit.
| Malcolm Hoar "The more I practice, the luckier I get". |
How many AC breakers are not tripped, and where are they?
Do you know that you probably have a breaker outside, maybe on the
wall next to the condenser unit? So make sure that is closed. Mine
has tripped a couple times over the years, though I never found out
why and never had to repair the AC.
So the AC has never worked since you connected the thermostat? Time
for you to review that.
There may be a high pressure switch inside the unit outside that
tripped, or some other protective device.
Do you know how to use a meter?
There are a lot of ways to go about this, becuse there are several
parts and in theory any one of them could cause trouble.
You need to measure the voltage at the compressor, on the 400VAC
range, or some range greater than 240. Don't touch any copper wires
with your fingers. This will verify if all the breakers are closed
and working right. Although you could save this for later and work on
the 24 volts circuit first. If you are looking for 24 volts at the
contractor, use your 400 volt scale and don't touch anything except
the plastic handles of the probes. Because you might end up touching
240 volts and you dn't want to blow the meter.
If you don't get something around 220AC at the compressor when the
thermostat is calling for cooling, figure out how the circuit for the
contactor is wired. The contactor is a high-current relay under the
cover panel of the condensor. There should be wiring diagram in the
papers you have, although I just found one stuffed into a space in the
The control voltage for the contactor is 24 volts. The contactor has
loads of screws where wires can be attached and it can be hard to tell
which ones are which. So you might want to measure from other parts.
Maybe the best place** to measure is where the wire from the
thermostat comes in, but the last time I did this, that led to wire
nuts, and for some reason I didn't want to take the wire nuts off. Of
course that was a friend's house, so maybe that's why. Anyhow, in
this case there was 24 volts there (AC I'm 99% sure) but the contactor
**This is especially true in your case because you replaced the
thermostat, and if you did it wrong, there won't be 24 volts at the
thermostat wire outside.
***Getting ahead of my story a bit here, somehow after I took off the
wire nuts, on wires that were only attached 8 inches away, somehow I
shorted the two thermostat wires outside. My friend said he heard a
click (which would have been a spark, but I didn't see or hear
anything.) But the thermostat voltage went to zero, and I had to
replace the AC fuse at the furnace. In this case, there was a spare
taped very near by. But be more careful than I and you won't blow the
If you stare at the contactor for long enough, you'll figure out what
some of the screws are for, at least. The big electric cable with
220v attaches to two of the screws, and your meter should show 220
there. Then right across, symmetrically sort of, are the connectors
that should have 220 when the contactor is closed. If there is 220 at
the house cable side and zero on the other side, the contactor is not
closing, and that means there either is no 24 volts to run the
contactor relay, or the 24 are interrupted by one of the many things,
mostly safety devices that are in the same area.
You can test the 24 volts when the 220 is off, and that might be a
very good idea since 24 won't kill you and 220 can, especially if the
grass is wet outside, or if you touch the metal case while you touch
either of the 220 wires. There is no GFI on 220 volt circuits, no
There is a temperture cutoff, a high pressure cutoff, a low pressure
cutoff, and maybe a couple more. They were all listed on the picture
or diagram in the papers that come with the condensor, or glued inside
the cover, or folded and stuck into the crack inside. Oh yeah, he
also one of the electric company provided radio controlled
disconnects, for when there is high electric usage. I couldn't open
that, and my first idea when the 24 volts disappeaed was to think that
the power company had turned off the 24 volts at that box. But with
the meter one could see that there was no voltage even where the 24
volt wires first came into the box, that it wasn't the
radio=disconnect that was disonnecting.
I used the voltmeter to work my way from where the thermostat wires
came in (There are only two pairs of wires coming in, the 220, and the
I leave one probe, say the black, in the same point, and move the
other probe closer and closer to the contactor, to see where the 24
volts fails. I use a wire with alligator clips on both ends to keep
the black probe connected. That way I don't have to control two
probes and can use all my energy to keep the red probe where it should
be, and I don't have to worry about falling over and to keep my
balance, grabbing on to something that turns out to have 220 volts.
When I blew the fuse above, I myself didn't touch anything.
Just make sure you're in a comfortbable postion so you don't start to
fall over and then grab something, so that you have control over where
each hand is, and you don't put it on something you don't intend to
keep your balance. I sit on my tush with my legs folded, and for me
that is very comfortable and stable. I would be afraid to do this
sort of thing on my knees, because I wouldn't think it was stable
enough for when the 220 volts was on.
It turned out that the high-pressure, iirc, switch had tripped, and in
this model it had a big red rubber cover, that covered a reset button
and all I had to do was push the button. But I don't feel I wasted
time checking everything else and blowing the fuse etc. Now I know
his controls inside and out.
His AC worked fine that day, but this was the very end of the summer,
and he hasn't used it since. Whether it will continue to trip, I
don't know. I sort of doubt it.
Your pictures show the inside of the furnace. The only thing in there
worth checking is whehter 24 volts is going to the AC outside when the
thermostat calls for cooling. This location may be marked on a
diagram, but it's a lot easier to find outside, inside the condensor
case, where there are only two pairs of wires coming in, 24 and 220.
Hmm, there was another photo that might have been this, but when I
went to enlarge it, it said "The photo you were looking for has been
You might like to ask DJ Otter Creek about it!
Here's a link back to your home page.
This post is not in the most logical order, for the sake of time, so
if it is confusing, write back with specific questions.
I wasn't clear enough. It's been 20 years since I replaced my
thermostat, and I don't remember if there is a separate wire for the
AC, let alone if your wire has a separate wire for the AC, but if
there is one, it's time to review if you connected it right.
I mean, because you don't want to kill yourself.
This is why you should keep it on a scale 240 volts or higher.
It used a simple glass fuse that I had at home, or that can be bought
at any Radio Shack or auto parts store.
BTW, what I did at this point is to push on the center, with an
all-WOOD thing, a DRY thing, a long dry thing, like a dry stick or a
chopstick, on the plastic, and if you push down almost a half inch,
when you hit bottom, the AC compressor (and fan) will start. If the
only problem is in the thermostat/24 volt circuit, and the AC circuit
breaker is on.
I only ran it this way for a second or two. There is no rush except
if the fan is not on in the house, the evaporator inside wwill
over-cool. But a second is plenty time, because it says that the
problem is that the contactor is not closing.
Well, in theory the contactor could be closing but one pair of
contacts could be so bad that you don't get the 220 on the other side.
The contactor is a double pole switch. It interrupts both sides of
When I see an AC in the trash, especially my own brand and model, I
take out some of the parts, so I already have a spare contactor for my
AC, and another beautiful like new contactor which will work for
almost any AC. But I haven't needed one yet. I forget how much they
actually cost, but even if it is only 20 dollars, I like having one
available at home.
You might have one too if you or a previous owner signed up for that.
I'm not talking about closer along the very same wire, but first on
one side of the temp-disconnect, then on the other side, etc. You
don't have to remove the insulating connection covers, you can stick
the probe in parallel to the wire.
And I wouldn't disconnect anything. Just use the voltmeter part. If
you're not near the 220, you can use some AC scale over 24 volts,
although my cheap meter, for use out of the house, starts at 200.
The diagram actually indicated there was a switch there, but it was
All the more important if it is one's own AC. But he might call me
again if he has more trbouel someday.
My god, child! I wouldnt let you anywhere near my A/C unit. You are
scary and very dangerous.
Why would you check voltage at the compressor terminals to check if
the breaker is "closed"?
I wonder what effect that silly contactor would have on that theory?
You should stick with what you dont know how to do.
One has to check if there is 220 inside the condensor unit. One has
to check if it is present at the compressor (or the fan, which is for
this purpose the same thing) Checking at the compressor also verifies
if the breakers are closed.
He said all the breakers were closed, but maybe the AC breaker has
failed. It's one thing you have to check, unless you skip that and
work on the 24 volts first and find the problme there, as I also
This was for when contactor is closed. I think that's obvious to you
and even the OP. I'm not going to go back and check if that was
expicit, but even if perhaps it wasn't, I said at the end that the
post wasn't in logical order.
Would I have to tell you that there will only be voltage at a lamp
when the lamp is plugged in? I'm sure the OP will understand.
It was good of you to point out something he might have a question
about, but I know what I'm doing and don't imagine otherwise.
The link was not a good one, can't tell you anything about the system
without the rest of the model numbers and serial numbers.
Your best bet at this point is to call your local Rheem dealer to come
check, service, and repair the system.
BTW, Hunter makes great ceiling fans, but there thermostats are crap.
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Oops! Looks like you followed a bad link.
If you think this is a problem with Flickr
Guess that link won't work. Since the only thing that changed was
the thermostat, I'd be tempted to recheck the wiring on the stat.
Christopher A. Young
You can\'t shout down a troll.
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