I have a packaged heat pump w/ Emergency Heat that is not working and does not come on at all. No lights or anything even when I switch it to emergency heat. Someone said that it could be my low voltage transformer. What is that and how do I check it?
You need to check the breaker fist and the disconnect on the unit. Then after verifying with a Volt meter that you have power. Your going to need to remove the panel on the unit. There should be a circuit board with a LED light blinking (this is assuming you have power), Count the number of flashes the look on the back of the panel or the installer manual. This will give you the fault code of what has failed. To test the low voltage transformer, again you need to verify that the unit has power. You will need to use a volt meter. The other possibility is you have a failed contactor or failed capacitor. To veriy your thermostat is working try turning on the blower (fan) to ON. If the fan comes on then you have power to the unit, and your low voltage transformer is working. Also, if your thermostat has batteries in it and if they are dead this will cause a no heat issue. Heat pumps are not easy to trouble shoot via the internet. I highly recommend you call a professional out to properly fix the unit. Remember IF you decided to go fishing and try and fix it, your dealing with HIGH voltage and sensitive electronics. So, poking around really is not a good idea.
A low voltage transformer on an a/c and heat system is a device that lowers the line voltage down to a safe 24 volts to run in control wiring to your thermostat to control your system. If your thermostat has a removable cover where you can see the wires underneath it is easy to see if you have no low voltage as long as you have a volt meter that can measure 24 volts ac. Make sure the thermostat is off and measure the voltage from R to any other terminal and you should read 24 volts nominal (more likely somewhere around 27) If you don't read 24 volts minimum you have a problem in the low voltage circuit. Most heat pumps will have some kind of low voltage protection such as a fuse or small circuit breaker in the unit so it doesn't necessarily mean the transformer is blown. The more important thing is to find the reason that caused it and that requires thorough understanding of the system. It's really best to have a technician diagnose this kind of problem.
