arcoaire 90% furnaces

[pneedham]

I have an arcoaire n9mp2 90% furnace . During the off cycle the inducer motor cycles on and off rapidly but in the heating or cooling stage it runs normally.
Any Ideas what is happening. I replaced the inducer motor pressure switch it still does the same thing. When I unhook the hose to the pressure switch it runs normally.

[heatseeker]

it runs in the cooling stage? thats odd. could be problem with relay on circuit board or other control wiring even t-stat. call a pro might be beyond diy.