I have a Ruud model #UBHC-15J13MFA HVAC system with a Rheem Model #44-42733-01 heating unit. The heating elements will not shut off unless I turn off the circuit breakers on the front of the unit. It doesn't matter whether I am running the AC or the heat. When the AC shuts off the heat continues to seep out of the vents. Needless to say this is pretty inefficient. I'm assuming it's a relay that is stuck open. The unit will operate if I turn off the left hand breaker but not the right. Looking at the schematic on the front of the unit it appears that the left hand breaker only controls the #3 element. The other two are controlled by the right hand breaker. Where can I find the relays to test them?

Sequencer probably stuck/bad,, sometime you can carefully tap them with a screwdriver handle and temperary unstick,, I don`t have a photo to show what it looks like,someone will be along with a picture I`m sure

I removed the cover from the circuit breakers and found the orange wire connected to the middle disc was fried for about an inch and the disc was in pieces. I'm assuming from the schematic that this is a limit control? Anyway, I switched the top one out to the middle position (the bottom one and the middle one are hooked up to the right side breaker) and leaving the left side breaker off, tried the AC again. I was still getting heat. I think you are right about the sequencer. I assume those are the two black modules with all of the wires attached to them? I tried tapping on them and it had no effect. How can I tell which is bad? It looks like they are jumped together. For a temporary fix I just unplugged the two remaining orange wires and taped the ends. The heat stopped. That should get me by for a few months until the weather turns ugly and I need the heat again.