92 SL2 ac question

While replacing the radiator fan I broke the high pressure, Discharge
coolant line.
The AC turned on a few times yesterday but today won't kick on at all.
Is there a switch that would prevent the AC from coming on with no fluid?
I use the AC to force the cooling fan to come on. Turning the AC on/off
for only a second keeps the fan running.
For some reason the fan doesn't come on until the temp is 3/4 way up the
gauge - even with new temp sensor.

Is it easy to replace the hose and refill the system? It's been converted
to 134 btw.

 

Yes there is a pressure switch. You should have your ac system sealed
off from the atmosphere. You could disconnect your compressor and fake
the signal from the pressure switch I think to get your fan to run. I'd
prefer people got their ac systems serviced from a good shop myself or
done lots of research. Some ac oils say their compatible with both r12 &
134 and I think they end up ruining things in a couple of years time.