i am pretty sure there are no daytime running lamps on a 90' integra...
Thermostat sticking. Replace thermostat and gasket.
is the blower motor running? or is it just not blowing hot air?
Your heads are probably warped from overheating. have them checked out by a machine shop. Sometimes they can machine them back to flat, but you might have to replace them.
Because it's sitting in the sun.
You mean the outside unit is running and blowing but the inside unit is not blowing? Shut it off! Who ain't blowing? Elaborate please..
Dimmer switch
they dont have day times....
Check the temperature gauge. If it is running cold, replace the thermostat.
did you try blowing it
Check your outside unit. Is the fan blowing? If not replace outdoor fan motor or the fan capacitor. If the fan is running then the compressor may not be. Usually a quick fix by replacing the capacitor. In most units a dual capacitor that is bad may shut down the fan or compressor. Call a HVAC technician to replace it. This can be very dangerous.
Is the compressor running ?