Print

[jksweld]

Its a 72 model trailer, so im assuming its the original. Im gonna pull the panel off in the morning and if I have a G terminal then im gonna go with what you told me earlier. But im gonna bet that the heating elemnts in the furance kick on thru the sequencer

[RSI]

If it is that old it might have an air temp sensor in the plenum that turns the fan on. If that is how it is set up you will need to add a relay.

[jksweld]

Im not familar with exactly how the air temp sensor works, but my fan kicks on first then the heat elements when everythings satisfied then the elements kick off and fan runs cool down period, dont know if that helps or not

[RSI]

Then there is a good chance there is a G terminal. When they use the air temp sensor the heat comes on first and when it gets hot enough the blower comes on.

[jksweld]

Ok thanks RSI. Im gonna leave work here in a hour n half and look to see. Gonna try and stay up today and work on finishing puttin it in, I hate swing shift!!

[jksweld]

No G terminal, and I dont see any air temp sensor in the schematics or in the electronics. I have 4 limit switchs, sequencer, transformer, and cooling relay. So now I dont know how Im gonna keep the electric elements from kickin on and get the fan to run??

[slimjim]

Are the heat elements 110 or 220? use a srap on aquastat to interupt the power to the elements and a relay to power the blower.

[Scott7m]

There def gonna be 220

[slimjim]

Then you could use the strap on to interupt the TT terminals on the heater and still power up the blower with a relay, not sure if honeywell makes a 220 aquastat.

[RSI]

An aquastat is not likely going to be able to handle the current of the heating element.

Is there a schematic anywhere on the furnace? You can always use relays to run the fan direct if there is no other way to turn on the blower with the furnace controls.

How many wires are going to the blower motor?

[slimjim]

An aquastat is not likely going to be able to handle the current of the heating element.

Is there a schematic anywhere on the furnace? You can always use relays to run the fan direct if there is no other way to turn on the blower with the furnace controls.

How many wires are going to the blower motor?

The aquastat can be used to interupt the TT wires to the existing relay on the heater

[jksweld]

yes heating elements are 220

yes there is a schematic on the furnace and I have 4 wires on the fan, red, yellow, and 2 purples. the red is hooked to the fuses and one purple to the cooling relay, other 2 are taped off

[jksweld]

Is there a way I can unhook something or jumper over or bug into and run just the fan off the cooling relay?? Cause the fan is the only thing running during the cool down correct?? I have 4 spade thermianls that are not used on my cooling relay.

[RSI]

The fan probably runs a different speed for cooling. If that speed is ok then no reason not to use it.
You may need to use a relay to make sure you don't backfeed anything. 

If you use a DPDT relay with 24v ac coil. You can use the normally closed contacts to connect the coil to the of the cooling relay. This will allow it to operate normally when no power applied to the coil of the new relay.

You would take the wires currently going to the coil on the cooling relay and connect them to the normally closed connection on the new relay.Then run from the common connection to the coil on the cooling relay.You will need to find out what voltage the coil is in the cooling relay and find a source in the furnace to supply it to the normally open contact in the new relay.

Then the new relay coil will be connected to the thermostat W connection and to the C terminal in the furnace. (If you don't have a C then we can figure out where to go with that)

[jksweld]

Also there is a sticker above the schematic that says "This furnace is easily adapted to include air conditioning" On my board where the tstat wires hook up one side is marked "heat" with my red and white wires going to tsat and the other side makred "a/c" with 2 lugs but no wires going to them inside the panel.