Have read in several post here the circumstances under which the PCM commands low speed cooling fan, but can't find similar posting on high speed fan command. This is only incidentally related to my problem. Would also appreciate any advice/insight into the following:

A/C quite last summer. Had new compressor and associated items installed and all worked fine. In early fall started noticing cooling abated when car was stopped, such as at a stop light. Cooling returned with forward progress. Checked fan operation and find that the fans cycle on (low speed) when high side pressure reaches about 200psi. Once fans are running high side pressure decreases-not sure at what pressure they cut out, but they do. Advancing the throttle with the fans running (low speed) yields low side about 43 psi, high side about 225 psi. Never get high speed fan.

Thanks for any info you can supply.