VT - AC not working on Cold Mornings

[national machismo]

Here’s a challenge.

My ’98 VT Acclaim Wagon had a AC compressor replaced with hoses a few years back.
OK thru the hotter months, but here on a cold Melb morning the AC won’t activate to defrost the interior screen condensation?
After getting to work and restarting after 15 min it activates – presumably from the warmth of the engine dissipating to some sensor?
Specialist AC mechanic can’t figure it out & cannot replicate scenario. Gas pressures are good. I can remove the relay and activate the compressor with a bridging wire….
Thoughts?

 

[lout]

specialist ac mechanic might want to choose another career
are you still running r134a or something different
so i am interpreting your post correctly
when it does not work the compressor clutch is not engaging?
there is a pressure sensor on the ac lines (i believe it is a pressure transducer not a switch)
i would think the system is a little low on gas or this sensor is reading incorrectly
which prevents system from operating
a quality scan tool can read this pressure
on a cold morning try playing a hair drier over this sensor before starting car
could also just be a weak relay
try the obvious first and then move to exotic ideas