I have a 10 year old home with a Lennox HS24 central air unit. When the
indoor thermostat calls for cooling (or heating) , neither the furnace or
the a/c turns on. When I set the thermostat for cooling, I can hear a
"click" as the unit attempts to respond but nothing happens (same situation
with the furnace for heat).

I can control the fan (which does work) from the thermostat. I've reset all
circuit breakers and the unit still does not run. I've checked the outdoor
a/c unit for obstructions, frozen lines etc. and everything appears (to a
layperson) to be OK.

I've got a call into a local HVAC repair company but, given the warm temps,
not going to be able to get anyone out for three days. Any simple
suggestions would be appreciated. We did have a power surge in the house due
to a lightning storm that tripped a couple breakers a few weeks ago. The a/c
did continue to function for several days afterwards. Would it be worth my
time and trouble to replace the thermostat?

Suppose to be in the high 80s next few days and I hate to have the family
suffer in the heat if the solution is one I could readily tackle.

Thanks!

wrote in message
...
I have a 10 year old home with a Lennox HS24 central air unit. When the
indoor thermostat calls for cooling (or heating) , neither the furnace or
the a/c turns on. When I set the thermostat for cooling, I can hear a
"click" as the unit attempts to respond but nothing happens (same
situation
with the furnace for heat).

I can control the fan (which does work) from the thermostat. I've reset
all
circuit breakers and the unit still does not run. I've checked the outdoor
a/c unit for obstructions, frozen lines etc. and everything appears (to a
layperson) to be OK.

I've got a call into a local HVAC repair company but, given the warm
temps,
not going to be able to get anyone out for three days. Any simple
suggestions would be appreciated. We did have a power surge in the house
due
to a lightning storm that tripped a couple breakers a few weeks ago. The
a/c
did continue to function for several days afterwards. Would it be worth my
time and trouble to replace the thermostat?

Suppose to be in the high 80s next few days and I hate to have the family
suffer in the heat if the solution is one I could readily tackle.

Thanks!

T-stat is not the problem since you can turn on the fan.

Do you have fuses at the outside disconnect? Have you checked/replaced them?
Have you verified that you have 220 v at the compressor? ( really
230 -240v )

"SQLit" wrote in message
...

wrote in message
...
I have a 10 year old home with a Lennox HS24 central air unit.
When the
indoor thermostat calls for cooling (or heating) , neither the
furnace or
the a/c turns on. When I set the thermostat for cooling, I can
hear a
"click" as the unit attempts to respond but nothing happens (same
situation
with the furnace for heat).

I can control the fan (which does work) from the thermostat. I've
reset
all
circuit breakers and the unit still does not run. I've checked the
outdoor
a/c unit for obstructions, frozen lines etc. and everything
appears (to a
layperson) to be OK.

I've got a call into a local HVAC repair company but, given the
warm
temps,
not going to be able to get anyone out for three days. Any simple
suggestions would be appreciated. We did have a power surge in the
house
due
to a lightning storm that tripped a couple breakers a few weeks
ago. The
a/c
did continue to function for several days afterwards. Would it be
worth my
time and trouble to replace the thermostat?

Suppose to be in the high 80s next few days and I hate to have the
family
suffer in the heat if the solution is one I could readily tackle.

Thanks!

T-stat is not the problem since you can turn on the fan.

Not really-all it means is that he can turn the fan on manually. Says
nothing about the AC contactor or gas valve circuits..

To the OP, can you hear a clicking at the condenser (outside unit)
when the stat calls for cooling?

Yes, I do hear a clicking noise at the outside unit when the thermostat
calls for cooling.

Thanks !

"Rick" wrote in message
k.net...

"SQLit" wrote in message
T-stat is not the problem since you can turn on the fan.

Not really-all it means is that he can turn the fan on manually.
Says
nothing about the AC contactor or gas valve circuits..

To the OP, can you hear a clicking at the condenser (outside unit)
when the stat calls for cooling?


Also, does the furnace blower fan come one when the stat is on auto
and calls for heat or cool? .

You could jumper the red and yellow wires at the stat (R and Y
terminals) just long enough to see if the outdoor unit comes on. If
it does, you need a new stat.

wrote in message
...
Yes, I do hear a clicking noise at the outside unit when the
thermostat
calls for cooling.

Thanks !

OK, then, check the fuses at the disconnect as the other poster
suggested..
And disregard my other post about jumpering the stat terminals...

"Rick" wrote in message
link.net...

wrote in message
...
Yes, I do hear a clicking noise at the outside unit when the
thermostat
calls for cooling.

Thanks !

OK, then, check the fuses at the disconnect as the other poster
suggested..
And disregard my other post about jumpering the stat terminals...

One other question-does the furnace blower motor (fan) come on when
the stat calls for cooling?

No, nothing happens (other than the previously noted clicking sound) when I
select either Heat or Cool.

This may be just strange coincidence but the unit wasn't working but I had
left the thermostat turned to Auto and Cool. We had a fairly strong t-storm
with heavy rainfall and the outside unit turned on and ran (and did cool the
house). Not sure how long it ran. This happened in the evening and it
wasn't functioning again in the morning when I got up.

I also ran the fan at one point and then turned the stat to Cool. The
outside unit did kick in and run.

This happened 24 hours+ ago and I have not been able to duplicate the above
since.

Jim

No, the fan does not come on when set to Auto (and either Heat or Cool).
The fan only runs when the stat is set to Fan.

Thanks !

wrote in message
...
No, nothing happens (other than the previously noted clicking sound)
when I
select either Heat or Cool.

This may be just strange coincidence but the unit wasn't working but
I had
left the thermostat turned to Auto and Cool. We had a fairly strong
t-storm
with heavy rainfall and the outside unit turned on and ran (and did
cool the
house). Not sure how long it ran. This happened in the evening and
it
wasn't functioning again in the morning when I got up.

I also ran the fan at one point and then turned the stat to Cool.
The
outside unit did kick in and run.

This happened 24 hours+ ago and I have not been able to duplicate
the above
since.

Jim

Sounds like a bad connection in the outdoor unit.or a compressor
overload thermal switch . There should be a service disconnect outside
and near the unit. Try turning the disconnect on and off a few times
(if so equipped). It may not be a fused disconnect unless you have a
utility interruptible system (2 meters). If there are circuit breakers
in your panel, turn them off then back to on and see if that makes
things work. If you do decide to check connections, make sure you
throw the disconnect and lock it out!

I have to say I'm not familiar with any interlocks that may exist in
a Lennox system so I'm hesitant to suggest jumpering the stat
terminals to see if everything will come on. It's rather puzzling that
the furnace blower motor does not come on when the stat is in auto
mode.

Good luck

The fan only running when the fan switch is set to ON sounds like a bad
thermostat fan switch.

The fact that the outdoor unit clicks when you are calling for cooling
sounds like no power to the outdoor unit.

Rain should have nothing to do with it.

Fan relay and wiring are OK. Compressor contactor coil is OK (clicking
sound).

Start changing parts and you may fix it eventually. Buy a window unit
for cooling now, run the furnace blower to make it bearable in the
whole house. Wait for the service tech.

Stretch

Thanks !

wrote in message
...
Thanks !

One more thing, change the batteries in the thermostat.

"Edwin Pawlowski" wrote in message
...

wrote in message
...
Thanks !

One more thing, change the batteries in the thermostat.


Definitely.

A quick follow-up: The thermostat was defective. Installed a new stat and
the system now works fine.