Have no idea where to start!

On the way home Thursday night I smelled coolant, pulled over and checked, recovery tank was cracked and blowing coolant out. The cooling fan has been on for a month or so, haven't had time to check if it's the switch like last time. Lower hose was cool, heater hot, so I took ti on the the barn, maybe 5 miles. When I got there it was still blowing coolant. I thought the thermostats were stuck so Fri I got new ones after finishing a job that was pressing. Today I pulled it in the barn to fix, in the time it took to build air and pull in, the tank was blowing coolant and lots of foam in tank. No oil, just foam that goes away after shutting off and sitting. I thought head gskt, but read on here where an air compressor can cause this. Back in Jan the air line froze, and blew the main line that comes off the compressor. After a new line and some alcohol all was good. The question is, what breaks inside the compressor and which line do I pressurize to check? I am hoping it is in the compressor instead of the engine. Good news will be welcome!!!

 

Dang, sorry bout that, it's in a 93 LTL 9000 Ford, 60 S 370/430 set at Detroit for 425 to 1800, 400 1800 to 2100. Put a water pump in last fall, but would a water pump pressurize the tank in 3 minutes?

 

Thanks for the replies, this had a sleeper but the p.o. removed it and added a dump bed. I hate that part but it was a really cheap dump compaired to a factory built one. I will check to see if the valve for the bunk is under the cab and blocked off or removed with the bunk. I was thinking the stuck thermos caused the overpressure and cracked tank, but it didn't have time to heat up any and was blowing coolant everywhere this morning so I am leaning to the compressor, but what goes bad to blow air into coolant?

 

Would you put a new head gskt on the compressor like an engine or get a reman compressor? Do the heads warp and crack like an engine or just stick a gskt on it and go?