3m 50 blows heat in cool mode

[sdb2012]

HELLO, I HAVE 4 WIRE SYSTEM

IT BLOWS HEAT IN COOL MODE
NOTHING IN HEAT MODE.

I TRIED SWITCHING W AND Y NOTHING.

THKS

[blaine]

What are the letters you have connected? What kind of heat do you have? Is it a heat pump?

4 wire normal convential system:
R to RC and RH connected for power
W to W for heat
Y to Y for cool
G to G for fan
TEST FOR HEAT, connect W wire to R wire and the heat should come on if you have gas or oil heat.

4 wire heat pump without auxiliary heat:
R to RC and RH connected for power
Y to Y for compressor
G to G for fan
O to O for changeover heat to cool OR B to B for changeover heat to cool
Nothing connects to W

[sdb2012]

I HAVE ELECTRIC HEAT

I USE
W-Y-RHRC-G

I SPOKE TO SUPPORT AND THEY SUGGEST THAT IS a DEFECTIVE UNIT...

[blaine]

First make sure the norm/pump is in norm and the gas/elec switch is in elec; and then BE SURE TO PUSH RESET or the switch positions will not be recognized. This insures the fan is turned on with the electric heat or you will not feel any heat in the registers.

It is unlikely the thermostat is the problem. When you raise the target temperature above the room temperature; on the home screen with the backlight on, the word HEAT and the FAN icon should should be blinking indicating the thermostat has connected the fan (G) wire and the heat (W) wire to the R wire (RH/RC connected). They will not blink without the backlight on and you must be on home screen.

The best way to test the heat without the thermostat, is to connect the R wire to the G first to turn on the fan. Then connect the W also to the R wire with the G and the heat should come on. If not, the problem is in the HVAC.

[sdb2012]

I RE CONNECTED THE OLD THERMO, AND THE SYSTEM WORKS OK

I TWISTED THE CABLES MANUALLY AND THE AC WORKED OK

I TWISTED THE 4RTH CABLE TO TEST IF I HAD A HEAT PUMP AND BLOWS COLD ( WE KNOW NOW ITS ELECTRIC )

TELL ME WHAT TO DO BEFORE I GO AND RETURN THE ITEM

THANKS!

[blaine]

IF connecting W and RC terminals on the thermostat terminals turns on the heat (with the fan running manually (ON), but the heat does not come on with the word HEAT blinking on the home screen (with backlight on), then the thermostat is suspect.

[sdb2012]

IVE CHANGED THE UNIT WITH NO LUCK

PLEASE SEE THE PICS

YOU CAN SEE YOU IS CONNECTED IN THE 3M

AND HOW DOES WORK IN THE OLD SYSTEM

[blaine]

I repeat, do the test below.

TEST: Connect the G and the W wires to the RC/RH wire. The fan should come on and the heat should come on.

1. If the heat does come on the HVAC is fine; if the heat does not come on the thermostat cannot turn it on either.

2. If the heat does come on with the above test, but not with the thermostat connected W to W, R to RC and RH, and G to G, the thermostat is the problem.

3. If the cool comes on when you do the test, that means the W and Y are somehow switched.

[sdb2012]

AFTER HAVING THE SYSTEM RUNINIG , I HAVE THIS ISSUE

COOL MODE WORKS OK
HEAT MODE WORKS OK

IN THE AUTO MODE, I PUT TARGET TEMP AT 74 ( ROOM AT 78 ) THE COOL NEEDS TO START AND SAYS HEAT ON THE DISPLY AND NOTHING HAPPENS

I HAVE HEAT PUMP WITH NO AUX HEAT ( I SET IT AS 'C' IN HVAC CONFIG)

ANY SUGGESTIONS?

[blaine]

Try putting it in COOL first and let it come on in COOL, then switch it to auto.