Does my Carrier model 58 DHB furnace have a cooling system ?  If not, why
does the thermostat have a "cool" switch on it ?

Hi gruthman,

According to the Owner's Information Manual for the 58DHB, no, it does
not have a cooling system.  Cooling is separate, and can be added by a
Carrier dealer:

"Ask your dealer about the addition of cooling, air cleaning and
humidification to your new heating system."

Carrier Owner's Information Manual
58DHB/SSB Induced Combustion Gas Fired Furnaces
http://www.gogeisel.com/geiselonline/support/Carrier/58DHB_SSB_OM.pdf

The thermostat is entirely separate from the furnace:

"There are many thermostat models.  Be sure you are familiar with
yours. Some thermostats simply stop or start the furnace as the indoor
temperature rises and falls.  Others have a FAN switch with AUTO and
ON set points."

Carrier Owner's Information Manual
58DHB/SSB Induced Combustion Gas Fired Furnaces
http://www.gogeisel.com/geiselonline/support/Carrier/58DHB_SSB_OM.pdf

It would appear that the thermostat you have was installed with an eye
toward the eventual installation of a central cooling system.

Hope that helps!

--Missy

Search terms: [ Carrier "58 DHB" ]

Thank you Missy.   I have the paper owner's manual but had not noticed
that section.  When I googled (do you guys know this is a verb now ?)
on my own, I saw that pdf but didn't actually read it.  It must have
been some form of denial.

Thank you for a quick, and honest, and accurate answer.  This is a
great service.