Technician found filter so clogged with sheet rock dust that light from the sun could not even pass through. This will cause the unit to lockout on high pressure because air cannot flow through a clogged filter. Installed filter left in closet by air handler. Temperature maintaining at 71° on arrival however, after replacing filter and inspecting system operations unit was able to raise temperature by a couple degrees in a short period of time. Recommend not leaving front door open when system is operating. Photos uploaded to file.