Honeywell MS3000 Owner's Manual - Page 13

TROUBLESHOOTING GUIDE IF... THEN... Thermostat loses program. u Check for loose battery. u Check that power switch is ON. Thermostat shows no display, unless HEAT or COOL key is held. u Check that power switch is ON. •l Check main switches, fuse and circuit breakers on heating equipment to make sure the thermostat has power. The heating control circuit powers the thermostat even when it is controlling air conditioning equipment. u Check the wiring connections to the thermostat. u Make sure your system uses 24 Vat. The thermostat will not operate on a millivolt system. u Jumper RC & Y or RH & W. If system comes on, thermostat needs replacement. If system does not come on, a problem exists in the system (such as transformer, relay or valve). 32 Troubleshooting Guide continued IF... Display goes blank less than 30 seconds before or after a furnace burn cycle. Display goes blank for several minutes during a long furnace burn cycle. Temperature display is incorrect. THEN... u Your furnace is interrupting power to the thermostat. This is not a problem, as the 9 V alkaline battery will be adequate to carry the program for the entire heating season. Do NOT use a rechargeable battery. u Check for dirty air filters or blocked registers. If registers are not blocked and the air filter is clean, an isolating relay probably needs to be installed on your heating system. See Table 1 in the installation manual, form number 69-8025. •l See "Recalibrating the Thermostat," page 29. 33 69-8026-2 Troubleshooting Guide continued IF... Furnace or air conditioner operates continuously. Thermostat will not turn heat or air conditioner on. Thermostat will not let you make a temperature setting. THEN... u Check the thermostat to see if it is wired properly. u Check the furnace and air conditioning systems to make sure they are operating correctly. •l Check circuk breaker on heater or air conditioner to make sure it has power. u Check that pilot light/power is on; this thermostat "steals" power from the heating circuit. u Verify wiring. u Check if you have already made 6 settings. A maximum of 6 settings per day are available. The thermostat will not accept a seventh setting. u Check if you have used all 8 available temperature combinations. A maximum of 8 heating and cooling combinations are allowed in total in your weekly 34