Diagnosed an apparent air conditioning failure and found a torn diaphragm in
the monovalve. This apparently allowed almost full heat all the time thus overwhelming the ac.

My maintenance records show that I replaced the monovalve insert with an MTC unit in August of 2011, about 64000 miles ago. The use of quality, OE parts instead of Chinese copies is a frequent topic on this forum. This site sells both monovalve inserts. An MTC is 25.50 + shipping. The OE is $130.50. I find it impossible to justify spending five (5) times the cost for an OE monovalve. I bought another MTC monovalve on ebay for $18.80 including shipping.

I will look forward to being forced to replace this Chinese crap in another seven years and 60k miles.