Fraser Johnson (York) TP9C won't ramp up in the morning

this is a new installation of a Fraser Johnson gas. I lower the temp at night on a manual thermometer and in the morning when I crank it up , it will not stay running to reach temperature. After it stops I lower the thermostat wait 5 minutes , crank it up , the furnace will start again. I might have to do this 3 or four times before it will bring up the temperature. THEN THE REST OF THE DAY IT WORKS FINE.
The past 5 error codes are 5 Amber - 6 Red - 5 Amber - 6 Red - 5 Amber
5 Amber says "Heating capacity is reduced due to restriction in the combustion air or vent system or clogged condensate drain ".
6 Red says " Gas valve communication error "

I have checked as best I can , none of these pipes appears blocked

Fraser Johnson is not interested in helping

Would appreciate any suggestions and advice on where to look for the cause.

Thank You
Peter

 

check filter, check limit switch for condinuity after the furnace shuts off, its a round or square with 2 wires going to it that measures heat in the furnace and can shut it off if it gets too hot.