QHY600 not reaching target temperature QHYCCD QHY600PH M · Dan Brown · ... · 4 · 193 · 0

Have you checked the UVLO status? See the product page on the QHY page for info in an appendix section.

To confess - I did not read all previously posted replies but I know that problem as well.

There are a couple of reasons for it - number one and that is an important one is the voltage for the cooling. Almost all supplies do not supply constant 12V as soon as the ambient temperature decreases and/or the cables from the supply unit to the camera are too long, too thin or too cheap. 
Another reason is the electronic system of the cooling regulation - you should read the manual of the camera and find the instruction how to reset the appropriate values according to QHY. Most times, it solves that problem.

I most recently had another QHY camera with a similar problem - when the ambient temperature was above approx 5 or 6 C, the camera cooling worked fine, but as soon as the ambient temperature was around 0 oder lower C, the cooling did not function properly anymore -it cooled down to -28C and indicated zero power. Returned it to the dealer and got it repaired within 1 week - the cooling electronics got exchanged under warranty…

I own two QHY600 - one C and one M, both cool different - the C reaches -30C difference without problems, the M reaches only -25C difference - I do not care, because the current is so small, it just does not matter anymore in these days - IMO. With my other QHY cameras (4 in total), I do not have any problems.

CS
Georg