Auto Air Conditioning & Heater Repair: 1992 Chevy K-1500 A/C problem, c lines, c components

Question
In 2003, I installed all (NEW) A/C components and up graded to R-134. This includes compressor, evaparator, condensor, bulb, dryer and cycle switch. System has perormed great. Lately, however while driving at highway speeds above 1500 RPM and 70MPH,  the A/C will go off line. With the fan switch selceted high the A/C will eventually come on/off. If I slow the truck down to 60-65 will also add in the A/C coming back on line.The 134 charge appears good per my manifold test set with no leaks noted. I installed a new cycle switch last week, but the problem still exsist. I believe this may be a electrical problem . Ideas?

Answer
Problem is usually to much refrigerant oil in the system and at high speeds the compressor builds up to much head pressure and shuts down the compressor.

Buy yourself some LONG A/C lines so you can put the gages on the seat next to you when you drive at theses high speeds and see what your pressures are doing.