"mm" wrote in message
...
On Fri, 21 Mar 2008 18:10:34 -0700 (PDT), stoneattic
wrote:

Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?

The whole story:

My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I

Well, it would have been best if you had figured out what ruined the
first relay. I don't know much about how these things are wired these
days, but it's very very unlikely the relay ruined itself.

I'll bet if you check the new relay, its contract points are fused
too.

What would ruin a relay? Maybe it's a 24 volt relay but somehow 110
volts it getting to the coil?

That would fry the coil, not the contacts

got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?

thanks