Hi Folks -
I've got an air handler in the attic - "hydro air" unit for heat and AC. The unit is 10 years old. Robertshaw t-stat. Air handler is "First Co.". I am planning to call our service techs regarding the problem below, but before I do, I would love to get some insight on possible causes.
Currently, when I turn the blower/fan on the t-stat to "on" (even if heat/cool setting is "off" - the fan would come on but then after a few minutes would TURN OFF. After sliding fan back to "auto" for a few minutes (say 5-10 mins) - I would try again and the blower would come back on. Sometimes it would stay on, sometimes it would turn off again. Normally, when the fan is set to "on" (not "auto") - it would run indefinitely.
Now on a hot day in Mass. - I've got the AC on - and basically the same thing: I put t-stat to "cool" - and with fan on "auto", I click temp down until I hear it click to call for air. The blower comes on WITH condenser running (cool air) - but only for a few minutes as the fan then STOPS but CONDENSER KEEPS RUNNING (because air temp is not satisfied). If I click temp up to cease the call for air and let it stand for a few minutes, and then click back down to call for AC again, it usually comes back on - but again only for a few minutes (i.e., the cycle repeats in failure...)
After letting everything sit "off" for a few hours - at the height of the day (presumably very hot in attic) - I again attempted to turn the AC on. This time - I heard the click to call for cool. I heard the condenser kick on and coolant pumping - but the fan did not come on at all. A few hours later in the evening, I tried again and the fan came on for a few minutes, but then shut off again.
In short - all circuits seem to be calling/responding appropriately except blower FAN is not staying on when needed (even when set to "ON").
Any insight greatly appreciated.
Many thanks -