A/C Problems on 1990 525i 5spd

[Pwr2spare]

When I start the car for the first time and put on the A/C all is fine. However, when I restart it later, air coming out of the middle vents are warm and the air out of the defrost and foot vents are warm. The A/C system is fully charged and the compressor is working but not cycling on and off, just stays on. The low pressure tube is cold to the touch. I was wondering if it could be the heater valves? Any help would be greatly appreciated.

[SRR2]

Even if you have a leaky heater cutoff valve, the compressor should still cycle anywhere above idle (and most of the time it will even cycle at idle if the ambient temperature isn't too hot). The heater core is downstream from the evaporator, so applying heat, deliberately or otherwise, doesn't affect cooling system behavior. How do you know that the "system is fully charged"?

You are correct that the heater valve could cause this problem, as could improper door operation within the system. If you have the driver's side temperature control fully CCW at cold startup, does the heater hose into the cabin warm up after you start the engine?

So the suction line is cold? And the compressor outlet line (to the condensor) is too hot to touch? And the liquid line into the expansion valve is only slightly warm?