Heat Pumps and Electric Heating - Air handler blower trouble

I have a Goodman heat pump giving me problems. The air handler blower is intermitant. Sometimes when the heat or cool comes on the handler blower does not. I have tried resetting breakers on both units and turning thermostat off for a while and even removing thermostat. For some unknown reason the blower will just start working normally again. When it fails to run, switching to fan on does not help.

I checked the voltage and I have 27 volts across all terminals except R / G. Here I have 9 volts. When it calls for fan on it goes to 20 volts. When the fan fails to run I still have the 20 volts from the thermostat so I don't think the thermostat is faulty.

I am going into the attic next and was looking for possible ideas. As you can imagine I don't want the compressor running with no handler blower, kinda makes a lot of noise!

Everything else seems to be working fine and there is no emergency heat on the unit since we live in Arizona. We also have new filters and all vents are open. System is about 3 years old.

Thanks for any help.

with a call for fan you should get a reading of 0 volts across R and G.

with a call for fan you should get a reading of 0 volts across R and G.

I pulled the thermostat off and disconnected the green wire. Then I put in 2 leads. One from the green wire and one from the thermostat where the green would connect. I then replaced the thermostat and turned on the fan. That is when I get the voltage across the R/G. Strange thing is with the fan off and heat not calling for fan there is a 9 volt pot. across R/ G. I was just doing it this way to see if the thermostat was actually sending a signal to the handler without having to go up in the attic.

I have come to the conclusion that the problem is the sequencer or what ever it is called. Everything else seems to check out except for the strange voltage across R/G with no fan on.

Remove stat and jumper red and green. If blower comes on, your stat is bad, if not your problem is elsewhere.

if you aren't checking from R to G you aren't checking anything.

Sounds like you are checking from G to a disconnected green wire. in which case with the thermostat not calling for fan you aren't checking anything.

if you aren't checking from R to G you aren't checking anything.

Sounds like you are checking from G to a disconnected green wire. in which case with the thermostat not calling for fan you aren't checking anything.

I was checking from the green wire to the terminal where the green wire was supposed to go. I then replaced the thermostat and turned fan on. This is how I got a voltage from G to G. (Blower wouldn't come on because wire was disconnected for test, make sense? I would have to draw it but it doesn't come out well here)

With the thermostat off I checked R/G terminals and got 20 volts. I replaced the sequencer and I now have 27 volts and the system sems to be working fine.

I found out why with no call for blower I was getting 9 volts. It was because of the way I was holding the probes. Using gator clips I got zero for no blower and 20 for blower on. Now with new sequencer I get zero and 27.

Glad you got it fixed.