HVAC Fan Problem

[webmaster]

I didnt SEE your post in alt.hvac. But if you DID post there, it was the wrong area to ask.

Here is another stupid remark that you can add to the list.....its broke. What is causing it? Well...since no one can see it from here, and we can only be left to assume that you have a gas furnace, since you state that it works fine in heat mode, and the blower is on a different circuit in heat mode then, that you have a bad fan relay, or a bad lead to the fan relay, or a float switch that is wired wrong and is now bad.... Putting guages on the unit is pointless..why would you want to do that? If you put guages on the unit with the coil freezing over, it COULD look like its running close to a vac, when its fine. There is a a wiring diagram on the unit..and no offence, but if you cant read it, you have no business working on the unit to start with.

[FreddyQ]

If your condenser compressor and fan are working ok and your inside fan is not, then I'd look for a schematic with the unit and trace your circuit out with a voltmeter. My trane has a schematic, but you have to remove some panel screws to see it.

Probably an air handler circuit board with a relay that is stuck or burnt out.

[MARK ASH]

Hi,

I have a Trane XL 1200. Fan does not come on automatically in cool mode. No problem with heat. I haven't had a chance to put gauges on it yet. I here freon getting to the evaporator and coils, and they frostover until I turn on fan manually. Any ideas? All I got was stupid remarks from alt.hvac.

Thanks Mark

[Art]

If you are putting it on manually at the thermostat fan switch, doesn't it seem like it has to be the thermostat? Either that or a board on the system. My carrier system has a bunch of LED's and instructions on how to read them on the inside panel. You might want to take the panel off your

1200 and see if there are any trouble shooting instructions. Either that or time to call in a pro. If the freon hasn't been checked for a while it might be a good idea to do that anyway.

[indago]

050422 0727 - MARK ASH posted:

Generally, the air circulating fan comes on with the compressor, and if it isn't coming on, then there is a problem with a relay, or maybe a fuse on a circuit board. If the coils are frosting up, then that is a sign that the compressor and freon system is working. Take a look at the system schematics and determine how the fan system works in conjunction with the compressor; then, make the necessary repairs. The fan motor generally has several speeds, and it will work at a higher speed in the cooling mode.

[tm]

heh, like you expected anything else? But, like i told you, you need a new vacuum solenoid. I mean, it's obvious right? Your fan doesn't come on. Go to Home Depot, ask for a Trane XL vacuum solenoid. Don't let them sell you a smokeshifter, or a bag of potting soil, cuz that's not what you want, you want a vacuum solenoid. Now others may pipe up with answers that you might think make more sense, but they shouldn't be trusted. Go with the vacuum solenoid. Luck with your project.

[TURTLE]

This is Turtle.

You have a Trouble shooting problem with the air handler and / or thermostat to run out. Your 24 volt control system is not sending 120 volt or 230 volts service to the blower motor. The only thing I could do or help with is for me to be there and run it out for you and say Yea, there it is. Troubleshooting is a skill and you must haver it in cases like this and tring to explain it to you as we go. Well that would be a 8th wonder of the world.

Now you spoke of alt.hvac being messed up. You get to see there where tech try to tell other techs how to troubleshoot over the internet and expect them to do it just like they like it and nothing else. You have alt.hvac as you see it now.

TURTLE

[stretch]

If the fan (indoor blower) does not come on automatically in cooling mode, and you can turn it on with the fan switch on the thermostat, then you have a bad thermostat. If it were a bad thermostat cable or bad relay or bad fan motor, that would not work. Get a new thermostat installed. Have the tech do a checkup while he is there.

Stretch