I have a Rheem electric central heating system that when in the heat mode will not turn on the blower when the thermostat is in the auto position. The heat coils will come on but the blower will not come on unless I put the fan switch on the thermostat in manual position. I am trying to determine if the problem is with the thermostat or in the relay inside the heater compartment that turns on the blower. Any assistance will be greatly appreciated.

Try and identify which wire from the thermostat controls the blower. There may be schematic at the air handler. Once you identify it, jumper it at the air handler to the R terminal. If the blower doesn't start up, it is the relay.

Has the stat been changed recently? If not, it is most likely, the fan relay is bad

I would say relay but with electric heat it could be the heat sequencer. One of the legs or tabs on the heat sequencer turns on the blower on a call for heat.

I would say relay but with electric heat it could be the heat sequencer. One of the legs or tabs on the heat sequencer turns on the blower on a call for heat.
Depends on the model some Rheem's use a sequencer for the fan and some have a relay.

My central electric heat had the heat pump switch and a large main switch/relay replaced this past Spring to fix the AC and it worked fine.
Now the heat side is acting up. Ducts are clean, filter new but now I'm getting a clicking noise from the outside fan. It is kicking on and off and usually, but not all the time, it's blowing cool air {heat element not coming on}.
The same repairman came over and said the problem is condensation and did nothing.
I live in the south and the temps haven't even gone below 40 degrees!
I think he doesn't know. What can I do? Any clues to this problem?