Do I have a bad compressor governor? Mysteriously, my air (brake) pressure will cease to build, or build to operating level (60-70 psi). This is on a '90 F-800. The air lines to and from the regulator are clean and dry. Intermittent problems are the worst ! Thanks for advice.

 

Change your governor. You should be building at least 110# pressure before the compressor cuts out. You can make adjustments on the governor to increase or decrease the cut-off pressure. At 60-70 psi your pressure will drop too low with just one brake application.