That, I'm not sure. My old Montgomery Wards compressor (handed down to me from my dad) long ago had a combination check valve/unloader valve that relieved pressure on the compressor head so it could start easily (I know this because the unloader stuck closed once, and I had to give the...
Pressure switch only needs to monitor the tank, and turns on/off the motor. With only one motor, no need for any sort of tee-ing, unless it's to tee it in after the check valve on the same port in the tank.
Does that make sense?