Bypassing a Fan Control Board?

[Windseeker]

After reviewing this, I do not think I can do what I am trying to do. I’ll check with you guys first before I give up.

Carrier:
Fan unit: FB4A
Heat Pump: 38YCC
Honeywell T-Stat model ???

I noticed Tuesday that the fan was no longer running in the house though I left in the “on” state. Then I looked at the T-stat and it showed “Heat-on” then “Emg Heat”. The outdoor unit is running, but no heat. What heck?

Upon taking off the covers on the fan unit, I found the relay on the fan control board was partially melted and the insulation on the wires connected to SPT, NC, NO wire were blacked or partially vaporized. Looking further, I found the Yellow and Blue motor wires chafed and charred as well as the unused Red and Black ones. Then I noticed that the fan had been replaced in 2005 and the knuckleheads did not bother to chafe guard the motor wires. The vibration sawed off the insulation on the metal chassis and the relay became a fusible link!

I called the local Carrier supplier and he wouldn’t sell a control board to the general public. In fact, he would not sell you the part unless you were a Carrier Dealer! Thank God for the Internet! I found it and ordered it all for $40 something dollars with shipping. While this puppy is in transit, I thought to jumper out the fan control board to make the unit run to get some heat. I hot wired L1 and L2 to the motor to make it run. I tried wiring Red 24VAC off the transformer to Red and Grey on control wires. It made the thermostat work but would not turn on the compressor. It just flashed “Heat-On”. I turned the thermostat off for I was afraid I would break something.

There is a light Blue wire that goes to the NC contact on the motor relay. It’s not hooked up at the moment. I assume that this is the feed for the 90 second additional runtime on the motor after R-G is broken. My diagram stops at the connector. My assumption is that if I hot wire Red and Grey controls, it will run and never shut off. I think I will have then bypassed the Thermostat controls. What is the flashing “Heat-On” looking for? Did I not wait long enough? Is that how it works and is there a way to make compressor cycle with the fan motor Always-On while I am waiting for the control board?

Thanks for any response in advance.

[Grizzly]

Windseeker.
I have attached a small wiring diagram.
It may help ignore the fact that it is 50hz as the components and other details appear top be the same on a 60hz drawing.
Apart from the fact that being the American version it HAS to be so much bigger!
And therefore un-post-able.

Good luck Grizzly

[monkey spanners]

If the boards been cooked its best not to bypass and run the system, how do you know the rest of safeties work? Could end up with no fan and the back up electric or gas heater running with no air movement.

[Windseeker]

Apart from the fact that being the American version it HAS to be so much bigger!

(LOL. Even though I live on the East Coast, I grew up in Texas where EVERYTHING is BIGGER!)

Thanks Griz. I did not have this information. By chance, if you have this internals of the FB4A, that would be great!

[Windseeker]

837583768377

Since I had this unit apart, I decided to clean the coils using mild soap and water. When I was cleaning, I found a leak at one of the joints. At first, I scratched my head trying to figure out what the tube did as it was “a tube to nowhere.” Then I realized this is a modification from compressor replacement a couple of years ago. The old TEV must have had a direct feed from the low side manifold that the new TEV did not need. So, the contractor soldered on a piece of pipe and terminated it. This theory is supported by the fact that this line does not show the same discoloration from age and the solder joint is cleaner. In addition, there is a left over clamp that must have been used with the old TEV.

My question is this: Is there a better way to cap off this port? Did it fail because of workmanship of the joint? Quality of materials? Perhaps, if I make this line significantly shorter it may not put as much stress on the joint. Should I clean and re-solder? Maybe taking it the tube out entirely and finding the equivalent of a bandage I could wrap around. Ideas?