Hello Guest, welcome to the initial stages of our new platform!
You can find some additional information about where we are in the process of migrating the board and setting up our new software here
Thank you for being a part of our community!
Check the wiring down from inside the car to the transmission, the fuse, and the relay first. If one of those are the problem, they're a less messy fix than installing a bypass plate and lets you keep the 4th gear lockout function.
No, it's from shortly after the sale.
Huh? Are you talking about modifying the air box to redirect the hot air intake (for examples, google: volvo 240 air box thermostat), or did you block off the coolant hose between the head/block and the interior heater core?
Interior heater core
Don't block off anything. Get the manual heater control valve from wagonmeister on here. Your heat control valve is probably leaking past the the door that shuts off coolant flow. It's a common problem with the thermostatically controlled valve used on the 240 from 1975-1991.