FRST run really hot IME

I remember many a summers day driving in traffic with the heaters on hot

FRST have a habit of melting the Fan relay in the fuse box you can tell its goosed when the interior fan stops working have a look it will be the charred yellow relay on the top fuse box.

IMO and experience you NEED an ally rad for FRST's

you could also try the Cool boost or water wetter products might help.