Chrysler Repair: 97 Chrysler Concorde A/C, chrysler concorde, postal mail

Question
What should the high pressure be on the A/C for a '97 Chrysler Concorde?  When I cycle the control from cold to hot and back to cold the A/C will actually blow colder.  What would cause that?

Answer
Hi Michael,
The acceptable pressure is a fairly narrow band and it is temperature dependent (the temperature of the liquid line at the condenser outlet line). The assessment of the level of fill is a dynamic test with the engine and A/C running in a prescribed manner, and you need a thermocouple clamped on the liquid line output of the condenser to access the temp. There is a graph that shows the proper pressure range as a function of that temp reading. I can xerox copy and postal mail you the pages that have the graph and the instructions for the measurement. Use the "thank and rate" tab to enter a postal address.
I can't explain why cycling the control would impact the performance but I suspect it is a minimal impact compared to main issue of sufficient refrigerant in the system. The logic settings of the controls could very well produce such an unexpected result.
Roland