Frustrated with subcontracting HVAC jobs that drag on and eat my margins

Been subcontracting out some ductwork mods on Carrier systems for a general contractor in the Phoenix area, slow season doesn't really exist here but these jobs keep getting delayed by their endless change orders. I quoted flat rate on the R-410a line sets and everything, but now I'm stuck waiting on their electricians to finish panel upgrades while my crew sits idle. Out here in Arizona the heat makes it worse, can't even stage equipment without it crapping out. Seen this crap on r/HVAC too many times, guys getting stiffed on subs. Someone in HVAC Techs Network group said to always build in a mobilization fee, wish I'd listened. Now my invoice is sitting at 45 days unpaid and I'm chasing pennies. FML, anyone got tips for locking in better terms with GCs?

Same shit here man, subs always get the short end.

How do you even find reliable GCs to sub for? Mine keep flaking.

SharkBite fittings on HVAC lines? Nah, fight me, they're a joke for anything over 20psi.

Felt that waiting game, kills the whole week.

Subs suck, better off solo on residential Trane installs.

Don't ever sign without a clear payment schedule, learned that the hard way on a zone 2 job.

Man, chasing those invoices is the worst part of subbing.

Put 20% upfront in your contract, and bill weekly progress. Works for me on most Lennox retrofits.

Been there with GC delays, it's exhausting.

Yeah, idle crew costs add up quick.

Goddamn GCs treat us like we're disposable, pissed me off on my last Mitsubishi heat pump sub.

Totally get the frustration, hang in there brother.

Echo that, subbing HVAC is a crapshoot sometimes.