Got A/C?

[69fleetside]

I have put a new a/c system(complete) with condenser fans,new rad.shroud&fan. It blows cool enough sitting still,but driving down the road
it seems to blow warmer. Could anyone tell me what would cause this?

 

[79Beast]

Hook up your gauges while you run the engine at cruising speed. What does the low side read? At cruising speed (using R134a) you should be 15-20 psi. Does the compressor cycle on and off? Is your charge too high? Granted, it should blow colder when you're running down the road due to increased airflow over the condenser, but if your charge is too low, either the thermostat or the low pressure switch could be causing the compressor to cycle on and off. Also, keep in mind that 134a needs 30% more condenser capacity than R12.