Hi,m
I have a Honeywell Chronotherm IV plus thermostat - the room temperature reading is off by 4 degrees.
How do I set it to the correct actual room temperature?
Thanks

Exact model number of the thermostat?

The unit just says Honeywell Chronotherm IV Plus, but the honeywell website says:

T8602D2018

You can adjust the temp display see thermostat installer set up.

http://customer.honeywell.com/techlit/pdf/69-0000s/69-1507.pdf

Many times I have found that the item that is being used to judge the temperature of the thermostat to also be out of range causing the owner to feel the thermostat on the wall is at fault.

Read instructions and adjust your thermostat only if necessary .

Thank you