The A/C at my lake house stopped working and I had a bad repair call.
The tech decided that the circuit board was not working and physically
damaged it when he took it out. When I checked out the system I
determined that the circuit breaker was the real problem. Any idiot
with a volt/ohm meter could see the breaker was bad.

I got a new circuit board and installed it myself using the wiring
diagram - it was very straightforward, and I replaced the bad
breaker. When I turned the system on it worked fine, except I could
not turn it off at the thermostat.

After some investigation, I found that the thermostat had been
completely re-wired, the red on the green, the green on the red and
other problems. I suspect that was the result of a visitor to my lake
place desperately trying to get the system working.

After I rewired the thermostat, the system works properly in terms of
the low voltage controls sending out the right voltage on a specific
setting, for example the fan comes on when the thermostat is set to "
fan on". When you set the compressor to start by moving the control
level on the thermostat below the actual temperature, the 24 volt
control to the starter relay on the thermostat is activated - but the
relay does not close. I have replaced the relay, but that did not
solve the problem. I would expect that when the 24 volts gets to the
relay terminal, the relay should close, even if it is not hooked up to
the compressor, but that does not happen. I have the relay wired
properly. I have a Coleman Air handler and a Trane 2.5 ton compressor.

Any help would be appreciated.

John Funderburgh

wrote:
After I rewired the thermostat, the system works properly in terms of
the low voltage controls sending out the right voltage on a specific
setting, for example the fan comes on when the thermostat is set to "
fan on". When you set the compressor to start by moving the control
level on the thermostat below the actual temperature, the 24 volt
control to the starter relay on the thermostat is activated - but the
relay does not close.

Got 24VAC at the relay terminals?

You seem confident that you've wired everything properly. If so, you should
get 24VAC at the contactor when the stat is set properly. If you are getting
24 VAC at the contactor, and it doesn't pull in, the coil is NG. If you're
not getting 24VAC at the contactor, check the connections at the air
handler, the common and Y terminals may be incorrectly wired. Also check for
any time delay circuits built into the system



wrote in message
oups.com...
The A/C at my lake house stopped working and I had a bad repair call.
The tech decided that the circuit board was not working and physically
damaged it when he took it out. When I checked out the system I
determined that the circuit breaker was the real problem. Any idiot
with a volt/ohm meter could see the breaker was bad.

I got a new circuit board and installed it myself using the wiring
diagram - it was very straightforward, and I replaced the bad
breaker. When I turned the system on it worked fine, except I could
not turn it off at the thermostat.

After some investigation, I found that the thermostat had been
completely re-wired, the red on the green, the green on the red and
other problems. I suspect that was the result of a visitor to my lake
place desperately trying to get the system working.

After I rewired the thermostat, the system works properly in terms of
the low voltage controls sending out the right voltage on a specific
setting, for example the fan comes on when the thermostat is set to "
fan on". When you set the compressor to start by moving the control
level on the thermostat below the actual temperature, the 24 volt
control to the starter relay on the thermostat is activated - but the
relay does not close. I have replaced the relay, but that did not
solve the problem. I would expect that when the 24 volts gets to the
relay terminal, the relay should close, even if it is not hooked up to
the compressor, but that does not happen. I have the relay wired
properly. I have a Coleman Air handler and a Trane 2.5 ton compressor.

Any help would be appreciated.

John Funderburgh

Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?

I don't know what you mean, by if the coil is out. If you mean the contactor
is out, yes, it should pull in if you apply 24 vac to the coil terminals.
This is of course assuming you've got a contactor with 24 volt coil and not
240 volt or 120 volt



wrote in message
ups.com...
Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?

wrote:

Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?

It sounds like you need a new relay.

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This is a replacement



"CJT" wrote in message
...
wrote:

Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?

It sounds like you need a new relay.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

RBM wrote:

This is a replacement


Are you sure you have the correct one, properly wired up?


"CJT" wrote in message
...

wrote:


Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?


It sounds like you need a new relay.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .





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wrote:
Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?

Um, no, if the relay coil is open then the relay isn't going to operate.
Are you sure you installed the right contactor?

Is it a 24 VAC coil on the relay? Or did you buy a 110 VAC coil?

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"Travis Jordan" wrote in message
...
wrote:
After I rewired the thermostat, the system works properly in terms
of
the low voltage controls sending out the right voltage on a specific
setting, for example the fan comes on when the thermostat is set to
"
fan on". When you set the compressor to start by moving the control
level on the thermostat below the actual temperature, the 24 volt
control to the starter relay on the thermostat is activated - but
the
relay does not close.

Got 24VAC at the relay terminals?

Should.... if it's a 24 volt coil. And if you've wired it correctly.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

wrote in message
ups.com...
Yes, I have 24 volts at the relay, and the voltage is activated
properly with the thermostat settings. When I manually operate the
relay (push in the contacts) the copressor starts properly.

Even of the coil is out, shouldn't the relay close when the 24volts
hits it?

Yes, it is strange. I have the correct relay, it is 24v, it is
identical to the one that was in the system prior to the service call.
I have 24vac coming to it, and the thermostat is properly controlling
this voltage flow. I can measure the voltage on the control wires
disconnected from the relay and it reads about 25vac. When I connect
the wires to the relay (and yes, I am confident I am wiring the relay
correctly, I made careful note of the hook up before I changed out the
relay) the relay does not close and when I check the voltage it reads
about half a volt.

BTW I really appreciate al the help.

John

wrote:
Yes, it is strange. I have the correct relay, it is 24v, it is
identical to the one that was in the system prior to the service call.
I have 24vac coming to it, and the thermostat is properly controlling
this voltage flow. I can measure the voltage on the control wires
disconnected from the relay and it reads about 25vac. When I connect
the wires to the relay (and yes, I am confident I am wiring the relay
correctly, I made careful note of the hook up before I changed out the
relay) the relay does not close and when I check the voltage it reads
about half a volt.

Either the relay coil is shorted or there is a high resistance
connection in the control circuit. Your voltmeter measures 25vac open
circuit when there is no load (ie. the relay coil) on it. Could be a
broken or corroded connection in the low voltage wiring, a bad relay/SCR
in the thermostat, or even a faulty 24v transformer. Does the
condensor contactor wiring go through the control board that you
replaced? If so there could be a problem there.

wrote:
Yes, it is strange. I have the correct relay, it is 24v, it is
identical to the one that was in the system prior to the service call.
I have 24vac coming to it, and the thermostat is properly controlling
this voltage flow. I can measure the voltage on the control wires
disconnected from the relay and it reads about 25vac. When I connect
the wires to the relay (and yes, I am confident I am wiring the relay
correctly, I made careful note of the hook up before I changed out the
relay) the relay does not close and when I check the voltage it reads
about half a volt.

BTW I really appreciate al the help.

John

It should still read 24V when the coil is connected. As the other
poster said, that could be due to high resistance in the feed, or too
low a resistance in the coil.

If it's the latter, your 24V transformer will probably get pretty hot.

If it's the former, you should be able to find the last point at which
there's still about 24 V by tracing back from the compressor. At some
point you'll find a component with a large drop across it.

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