central AC and Heater not working

LYM123 go back and add your own post.

Heater and A/C won't turn on

I tried to turn on my heater recently and haven't had any luck. Tried switching on the AC instead to test it out and nothing either. Had the gas company come out to check pilot light and that was wasn't the issue. The gas company tested my thermostat and suggested I try replacing that. Well I did that and still no luck. I have a thermostat upstairs and one downstairs. So now new thermostats.

I have a Lennox G27M series furnace. Read somewhere that maybe its the circuit boards that needs to be replaced. Some said to clean the sensors in the furnace. When I unplug the furnace and plug it back in, blower turns on and then stops. Green LED lights blink slowly on the control board.

Any advice would be appreciated.

1 furnace and 2 thermostats would tend to indicate you have a zoned system. check the zone panel.

hi make sure you have 24 volts from main transformer first .are you able to check this ?>

Not sure where to start HVAC Dude. Would you be able to hive me instructions? Someone had mentioned checking the zone panel since I have a thermostat downstairs and one upstairs. Not sure where to find that panel either.

Do you have an electrical tester to check for votages?

Yes, I do have a tester.

If you have one system and two working thermostats then the zone board would be somewhere near the inside unit, near the furnace, possibly on a wall or even laying on or attached to the furnace. There'd be wires from the furnace to the zone board.

Now if you have two individual systems and one stat per system than you would not have a zone board as it'd most likely be one stat per system.

lym123 said:

I tried to turn on my heater recently and haven't had any luck. Tried switching on the AC instead to test it out and nothing either. Had the gas company come out to check pilot light and that was wasn't the issue. The gas company tested my thermostat and suggested I try replacing that. Well I did that and still no luck. I have a thermostat upstairs and one downstairs. So now new thermostats.

I have a Lennox G27M series furnace. Read somewhere that maybe its the circuit boards that needs to be replaced. Some said to clean the sensors in the furnace. When I unplug the furnace and plug it back in, blower turns on and then stops. Green LED lights blink slowly on the control board.

Any advice would be appreciated.

Click to expand...

First, check the circuit breakers again, Then, does the thermostat use batteries? Maybe they need replacing? Perhaps the programs in the t-stat were altered? If all this is OK, turn off the power to both the outdoor and indoor sections. Take the t-stat off the wall and make a sketch of which color wire goes to which terminal. Remove the wires from the terminals. Twist together the bare copper ends of the wires from terminals R,G and Y, making sure that you have a good connection. Set the wire from terminal W out of the way. Turn on the indoor section first and then the outdoor section. If everything comes on, the problem is the t-stat. If not, you'll have to check the transformer in the indoor section.

With the power on an the thermostats in off position If you can check between the R & w , r & g ,r & y terminals also check the r terminal and ground . See what voltage readings are and let me know

There is a 24 volt transformer that powers the thermostat... Power from it controls the gas valve, the ac outside, and the blower...

There is probably a circuit board that tells your furnace and ac when to operate, this is the control circuit... I want heat ---> I want AC ------> Run blower motor ----->

Blinking led would mean 24 volts ok.

Thanks everyone dor your input. I caved in and called a HVAC repair man to look at it. Looks like the zoning panel circuit board was burnt out. I knew something was odd when I smelled burning plastic when I tried turning on the heater.

So the repair guy told me it might be better to just have one zone as oppose to have dual zones. So now the downstairs thermastat controls entire houses airflow.

Heater works now, however it doesn't turn off automatically after it hits its desired temperature. Last night I manually cut it off at 2:30am when I was burning up. And I thought the entire house was suppose to be warm, however I found that downstairs was much cooler that upstairs.

So now I have a set of new issues, but at least its warm in the house now.

hi glad its almost sorted out ,, but the service fella shudda checked out the full opertation of heater and made sure it al worked ,,,