Grundfos water pump MQ3-45B. Will stop after frequent use. I have to turn it off and on to reset it. Control panel?

There are several possibilities here. All involve water pressure. The first is that you have a water leak between the pump and where the water is going to.
The second is that the pump is not getting enough water to it so it is sucking air well as water in an attempt to give you water perssure. This could be caused by not having an inline "one way" valve on your supply line just before the pump ($30.00).
The third involves two little screws on the control where your electical connection is. These two screws control the high and low pressure settings of your pump. If your high setting is too high the pump will simply keep running trying to do the impossible, If there is not enough difference between the high and low setting the pump will also keep on. running.
Another possibility is that the pump has had debris (sand, dirt, mud, etc) sucked through it and has damaged either the housing or more likely the impeller that spins the water creating the pressure.Ther is also an internal seal that can be damaged by debris.
The final possibility is that the pressure control unit with the two little screws I mentioned earlier has failed and is deffective.

Most importantly if the pump is running hot please stop using it! You are at risk of fire and possibly the loss of your home and loved ones. Grundfos pumps can be serviced by a professional technician, Parts are readily available and not extremely expensive. I would not recommend doing it youself if it is the pump.as some specialty tools may be involved depending on the problem. You will become frustrated very quickly.
A fast solution is to buy one of the cheap plastic pumps ($169.00) made in China. They are amazing for the price and will run with no problems for years if your water is free of debris. Fixing your Grundfos may run you the same amount and you maybe without a pump for a week or more depending on the technicians work load.
I am not saying "Don't fix your Grundfos" but you don't need to be in a panic about it either.

Sounds like 2 problems:
1) Crossover and 2) Setting timer
Recirculation system has check valve that stops backflow of water when pump is turned off.
When check valve is clogged with sediment, or has worn out, then cold water enters hot pipe or hot water enters cold pipe when faucet is turned on.
Take apart connection where grundfos connects to both hot and cold pipes, and clean with white vinegar or CLR.
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/Water-heater-recirculation-system.html

Open following link for setting typical FM/1 analog timer module on Grundfos recirculation pump:
Your timer module may vary in appearance.
Slide switch selector might be located below timer dial.
http://waterheatertimer.org/images/IMG_9325-grundfos-timer-800.jpg

Grundfos timer and pump operate by plugging into ordinary 120V outlet.

1) If outlet has power, then dial on timer should rotate.
If dial is not rotating, then check power to outlet.

2) If outlet has power, but timer is not rotating then timer has gone bad > if grundfos pump is working but timer is not working, you can buy cheap plug-in timer and use that as the timer.

3) If outlet has power and pump is not working, then manually rotate timer dial to see if pump will start.
If pump will not start, then you need a new grundfos.
There are no repair parts for these pumps, and nobody at Fixya has reported taking Grundfos apart and repairing it.
My Grundfos pump will not come apart.

4) Following link has links to Grundfos installation manual, website, product manuals, and contact.
http://waterheatertimer.org/Water-heater-recirculation-system.html#Grundfos

5) To set timer: Grundfos timer dial has movable pins that are used to set on-off times.
When pins are pushed out, timer turns pump ON.

6) Rotate timer dial clockwise until current time lines up with arrowhead located on inner dial.
Dial rotates as time passes, and pins move a lever that turns pump on-off.

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on Grundfos or any do-it-yourself project.
Fixya is always less expensive than a service call.

Diagram showing timer tabs being pushed in or out to set programs:
http://waterheatertimer.org/Water-heater-recirculation-system.html#Grundfos

Grundfos illustrated installation guide
http://waterheatertimer.org/pdf/Grundfos-L-UP-TL-043-install-photos.pdf

Rotate programming ring clockwise until current time lines up with arrowhead on inner dial.
Current time must be reset after power outage.
Tabs located around programming ring control timer functions.
Each tab represents 15 minutes.
Tabs push in or out using a pen.
Tabs out = grundfos ON
Tabs in = grundfos OFF
Set manual switch to TIMER and timer program operates pump
Set manual switch to ON or OFF to override timer program

Grundfos is a sealed unit and not a repairable item.
The timer dial should turn.
And pins located around dial control ON-OFF functions as timer dial rotates.


Does the receptacle have power?
If receptacle has power, and Grundfos is not working, then it is broken.
Grundfos manuals for UP series pumps do not show breakdown or parts list of any kind.
http://www.us.grundfos.com/web/download.nsf/Pages

Bigger question:
Why don't you have hot water?
Is water heater functioning?
Water heater is a separate appliance from Grundfos pump.
Grundfos pump circulates hot water from tank into the lines so there is no waiting for hot water ... but hot water heater should still make hot water.
http://waterheatertimer.org/Water-heater-recirculation-system.html

Add a comment about water heater if that is also a problem.
You could have 2 problems, and water heater is main issue.

For do-it-yourself electric water heater repairs:
http://waterheatertimer.org/6DIY.html

Grundfos is a p. o. s. I have a new system cu 301 and I have had to get it repaired twice by Fogle Pump and Supply. These guys are real rip of artists in Washington State and should be reported to the BBB. Dont Use Fogle if you need a well

it sounds like a relay for the auto shut off ....http://www.smarter.com/water-pumps/grundfos-mq3-35-3-4-hp-pressure/pd--ch-47--pi-11277834.html

The control unit is faulty, I had that problem twice.. I have now bypassed the control unit and use a normal pump pressure switch to control..works fine..The Grundfos company at first said I had to have air in the lines then admitted the control assy. was at fault. after two new units in three years I did away with the control unit.

Are you able to check for power to the pump with a mult-meter. If you have power you the know the pump has siezed (flat spot on the motor) if there is no power then you know there are issues with the controls.
I hope this may have helped,
Tom

check air press in built in tank.