For some time I have noticed a noise every time I turned the water pump on or off from the bathroom sink; sort of a zziit, zzitt sound. I thought it was the relay that provides 12 VDC to the pump. This morning I decided to try to locate that relay from the sound. The noise turned out to be from the fantastic fan by the shower; turn on the pump and the cover motor for the fan would activate for an instant, turn off the pump and the same thing. All three pump switches cause the same thing to happen. It does not happen when the fan cover is closed. It makes no difference if the fan blade is turning or not. The fan in the toilet is not affected.
Anyone else ever notice this or have an explanation?
Dick,
I notice almost the same noise when the water pump tries to shut off. In my case the pump is an electronic Shur-flo model and it is coming up against the accumulator press. After three tries/noises, it quits. No heat ever builds up in the pump motor so I don't think it is hurting anything. I hadn't noticed any noises with my Fantastic fans.
Dick,
I'm not remembering which water pump you have. If the Aquajet 5.3 I do recall our old one used to cause the "info" menu to come up, translucent though - not full, on our satellite receiver output ??? The new one doesn't do this. I remember reading in the Aquajet Troubleshooting Guide, page 5 (shown below)

that the pump could be a source of electromagnetic interference and a line filter was available. It's possible other brands of pumps could have the same issue. I know one of our fluorescent light ballasts polluted the 12V feeding the A/V IR repeater and Steve had to add a filter for its power.
You might also double-check the electrical connections for the pump, particularly the ground.
Michelle
I talked to Fantastic Fan tech support. He suggested I check voltages to the fan and try to find out what else is on the same circuit. He seemed concerned when I told him that when I turn on the bath area 12 vdc lights it causes the fan to slow slightly. He says the fan should not draw more than 3 amps on high speed.
I haven't done any measurement yet. Does anyone else notice the fan speed change when the lights are turned on? I just hear a change in pitch; can't really see any change in speed.
I did pull the fuse and the fan and lights are on the same circuit, but the water pump switch is not.
Our bath ceiling fan slows when bath lights are turned on. No problem and normal for our coach.
Thanks, that's reassuring. It seemed normal to me too, but just wanted to ask.
Ditto Barry and Cindy's comment: Bath ceiling fan slows when bath lights turn on. Normal.