I bought a Honewell RTH230B to replace and mercury base Honewell T822B thermostat.

The old thermostat had the following wires:
Blue
Red
Yellow
White
Green

I wired the new RTH230B as follows:

Red = to Rh jumper on Rh and Rc
Yellow = Y
White = W
Green = G
Blue = did not connect.

When I wired like this the system goes on but I only get hot air through the vents. There is no cold air coming out even though I have it at 65! Not sure what I am doing wrong. Any help will be appreciated.

I disconnected the new unit plugged back to the old unit and it works perfectly fine!

Youy forgot the blue wire.

If the new thermostst has no place for the blue wire you have the wrong thermostat.

Could it possible be that you did not READ the instructions?

Just in case you tossed them out here is another on. Please read this one.


http://customer.honeywell.com/techlit/pdf/69-0000s/69-1800.pdf


I believe the stat is for on stage heat which means it will not work on a heat pump with aux heat.

Here is a note from the instructions


Note: These thermostats are not compatible with heat pumps or
Multi-stage systems

I wonder sometimes.

Thanks for the response. Actually I am using the thermostat to control my A/C unit in my apartment.

I went through the instructions, but couldn't find where to put the blue wire. I believe the blue wire in the old stat is on port O. This new unit does not have a port O. Looking at the available port on this unit:

Rh
Rc
Y
W
G

Where would I put the blue cable?

Thanks for the help

You do not need a blue wire for strait A/C.

You only need the blue wire for heat pump use.

You have a heat pump system!!

You have the wrong thermostat!!

Do you understand NOW ?

This is the same in so many words that I said the first time.

Read the link I posted

It is all in there.

Here is the note again just in case you did not read it before.

Note: These thermostats are not compatible with heat pumps or
multi-stage systems


You have a heat pump system because you have a blue wire that is connected controlling the reversing solenoid.