Carrier Combination Unit Problems

#CARRIERMAN

Hi Fellow techs.

This post is to help those who may have a Carrier combination unit that is having nuisence ignition lockouts. The units you will find this on will be the 48GP, GS, GX in the Carrier line, however this will apply to the Bryant and Payne versions also. The lockouts will be random and usually occur when the temperature makes abrupt changes. To remedy this, locate the ground going to the ignition / blower control. Remove the ground wire from the board and cut it off of the ring terminal and discard it, you don't want a wire nut on this wire, that would be another point for corrosion to occur. The ground wire will be attached with the blower ground. Make a new ground wire and run it to the physical equipment ground that goes back to the house. This will be the ground screw to the right of the board. If there is no physical ground you can drive a ground rod to attach the board ground too. Reattach the blower ground to the original screw. I have found that the back EMF off of the blower is what has been causing this problem. The chasis ground builds formicary corrosion around the screws in the chasis and can no longer bleed this off. The result is that it finds the path of least resistance to be the low voltage circuit. Hope this helps one of my fellow techs., to keep from having to do this on one of those cold nights in waist deep snow.

Good luck
Rusty

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