HEVAC help

Nothing works on the panel. Changed the panel nothing works doh.
Advised to change final stage resistor. Doh doesn't work.
Need to do A DIAGNOSTIC is it worth buying a mangoose.
Finally will the unit stop working if the gas has run out.
I thank you all in anticipation and yes all fuses are good.

Check your FSR installation, make sure it is correctly seated, easy to get this wrong

HEVAC will still work if the AirCon gas runs out

Check all your connections to the replacement panel

A diagnostic tool may help...  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Thank you I will check connections and useful to know about gas will update as soon as I can.

Just a bit of feed back, it was the hedgehog thingy at the back and the number 12 fuse.

So thingy or fuse?
Both were gone?? 2010 3.6tdv8 180k km.
sold 06 td6 160k
Sold 03 td6 260k

It was the FSR final stage resistor, I changed it but it still didn't work I was scratching my head then decided to have another go at the thingy and
I realized that it was not in its correct seat so after a final push and hearing the quite audible click that announced its final resting place and checking to see if that worked.....nope, scratched my head then decided to check the number 12 fuse of which was a 10 amp. Blown ha ha changed that and it all worked fine for a while but then the fuse will blow again so decided to put a 15 amp in and now works fine.