I have a -AC message on programable thermastat

Did you check the batteries too? And do you have the temperature settings right for each program?

Hello, when the last time you have had your truck coolant system serviced? The anit-freeze needs to be reomove the coolant system flushed out (cleaned) Also, maybe a sticky themrastat and it will need to be replace along with a new radaitor cap.

. Clean the radiator inside and out---flush the inside with flush cleaner especially designed for auto coolant systems.
Flush the engine block this can be done with the radiator at the same time.
Replace the thermastat
replace the radiator cap with the correct pressure cap. GB...stewbison

on a call for air conditioning your therrmastat brings the indoor fan on and the out door unit at the same time. Since your fan comes on in "fan" mode, it sounds like you need a thermastat. For temp. cooling just turn your fan switch to "on" and turn system switch to cool and set desired temp. System will cycle off and on but fan will not shut off until fan control is set back to "auto". I suggest replaceing thermastat

The Thermastat has nothing to do with your AC becoming on at all because the Thermastat has to do with radiator fluids going into the engine to keep its high temperatures in check not your AC. You need to check the connection of the switch with a multimeter to see if current is getting to it and it is not then check the fuse for your AC in fuse box so see if this fuse is blowned. If the fuse is blowned tells me that there is a short in the wiring to the AC switch.

Can you give me model #'s of thermostat & AC unit, as well as upper unit? Number of or at least a description of thermostat, and numbers for ceiling assy should be visible when filter taken off, as well as # for upper unit should be tagged on bottom of unit on roof.

Heat pump Thermastats have Terminals RYW/OW2 G C. I run into this a lot with people buying tStats at home depot. To wire three sages of heat you must have correct tstat. one stage cool and three stage heat. You have to have enough wires at the Tstat. I use white first stage brown second and grey or black third. Make a diagram where each wire goes. Remember to trun of air handler power or you will short the transformer or blow low voltage fuse. Yellow cool, green fan, most of the time blue is c unless it is a battery tstat. orange is O. Red R ot power wire. Rusty

red power
yellow ac
green fan
white heat

GOto the iside unit itself. and remove the door and look for a terminial strip that the thermostat wires from the thermostat connects to and write down the colors wires and the letters they're connected to and connect the same to the thermostat .... they should be... r--red=power w-white=heat y--yellow=cool g-- green=fan! See which wires/ colors they're not using and bend back! Thank-you-very-much!

Generally speaking; R terminal to Y terminal on the back plate. However you may have a transformer problem which would not give you power to the R terminal in the first place. Jumpering R to Y should make the outside condensing unit come on if you have power.