Air Conditioning - Attic Split A/C System Blower: Won't Shut Off ?

Hello:

Have moved into a 30 yr old house that has a split type of air conditioner in the attic.

Have never had one before, and would like to ask the following, regarding a problem that I can't dope out.

The unit has the condenser outside, and the evaporator section, and apparently a blower in the attic.
Attic space is very low, and just about impossible for me to crawl in and examine what's there, exactly.

Anyway: When I turn it on, it the A/C seems to work. The only problem is that I cannot get the attic
blower to ever stop running. The only way seems to be a typical wall type switch in the attic
which shuts the AC off totally for the blower. Obviously, it's meant for turning the AC for servicing, etc.

The unit is controlled by a TRANE brand thermostat, that looks pretty "typical."
Has a dial for temp., a thermometer, and a slider with 3 positions.
These being: FAN in the upper position, OFF in the lower position, and AUTO in the middle position. None of them seem to effect the blower's running.

I guess, but am certtainly not sure, that it might be that the thermostat slider has welded contacts as it is probably about 25 years old by now, or a "stuck" relay (in the attic blower assembly, or possibly in the condenser unit outside-not sure where they place the controls for this sort of thing ?) somewhere, or... ?

Any thoughts on this would be most appreciated.

-Would sure like to have the thermostat work things, normally.
-Should i buy a new thermostat ?

Much thanks,
Bob

With the a/c off at the stat and the blower switch in auto remove the stat from the wall and disconnect the green wire and see if the blower shuts off.

With Matt If you pull the G wire off and it still runs go up and hit the unit in the attic hard with you hand. Can be the fan relay is stuck on if so get a new one.


ED ;)

Hi Guys:

Much thanks for help; appreciate it.

If removing the green wire (what should the terminal be labeled ?) does
shut the fan off, what does it imply is defective ?

And, if it doesn't ?

BTW: where is this fan relay usually found ?

Thanks,
Bob

G on the tstat is to turn the fan on. So if you pull the G wire off the tstat and the tstat is fan auto and tstat off the fan stopped then its in the tstat. With G off the tstat and fan still runs its in the fan relay in the unit in the attic.

ED ;)

Hi,

Thanks again.
Will try.

BTW: this thermostat and system all date back to the late 1970's !

Was it still (likely) a green wire then ?
Any terminal labeling by the screw ?

Bob

Wire color may or may not be green. Terminal should be marked "G".

The fan was G on a tstat even in the 60's :D

ED ;)