Mosquito Magnet Forum

I have a MM defender that was going to be put to the street until I saw this site. So I took it apart and clean everything and tested the gas valve w/ a magnet. Ohmmeter tested the thermo switch, soaked & cleaned the nozzle and filter. I did notice that the plastic screw head is missing from the thermo switch. I used a high temp silicone to reattach it.

I started it up today and the fan started at once and after about 5 minutes the fan slowed and the ignitor turned on (white smoke observed from exhaust port, I think it was just burning of the cleaning agent). After a few minutes I could feel warm air exiting from the exhaust fan screen. The MM ran great for about ½ hour, then just shut down. I did notice that the plastic screw head is missing from the thermo switch. I used a high temp silicone to reattach it. I used the pressure-reset valve, try to restart, and had the same results.

1. Is there a shut down /restart sequence? Is this normal?
2. Once it starts should it continue to run?
3. How do you check the gas valve w/ a battery? I used a magnet and could hear it click. Can also hear click when fan slows down.
4. Should I remove the plastic screw and replace it?

Any suggestions would be great; mosquitoes are getting busy, and thanks for any help.

I suggest replace the nylon screw and also clean the mating surfaces of the thermistor/burner. The thermistor is probably not making good contact with the burner housing, causing a false low temp indication. What's the LED doing during all this?

I'd also check the regulator. See this thread: http://mosquitomagnet.freeforums.org/defender-fixed-bad-regulator-t9.html

OK, I cleaned the mating surfaces of the burner housing and the black sleeve that the heat pickup fits thru, and replaced the plastic screw. I checked the regulator and had the low hiss and pungnet smell, so I quess the regulator is ok. Led light is on solid for the half hour it works then when it shuts down it goes to rapid blinking.Also, did the tissue test when it was running and had suction. Started again this morning with same results.

Still sounds like something's up with your gas flow. Try doing a flame test by connecting the solenoid to 12vdc and connecting the reg to the LP tank and see if the flame sputters, or dies out after a half hour. I use 8 D batteries in a cheap radio shack holder to provide 12v for the solenoid. Also when the burner was put back together were the vent ports clear of silicone etc?

Yesterday I got a new nozzle so I decided to take the unit apart again. There was no silicon clogging any air flow ports. I did use compressed air to blow air up the hose to the gas valve unit and no air came thru nozzle until I used a magnet to open the valve. I heard a click and air started to flow thru the nozzle. This was with the old cleaned nozzle. Should I put the unit back together or try to light the gas flow with the valve/nozzle assembly only attached to the tank? I also purchased the Charbroil hose/regulator unit, which will be my last step in this repair. Thanks again for your help.

Might as well verify the flame while you have it apart. At least once you should test valve with 12v to verify the solenoid coil is good. I'd also bite the bullet and use the new nozzle & regulator straight away.

Ok, checked gas valve w/ Batteries and it worked. New nozzle, new regulator. Steady red light for 1/2 hour, then stopped working.

You have a pesky one. It could be a bad solder joint or component on the controller board that works when the unit is cold but fails when warm. After the 1/2 hour shutdown, what happens if you immediately restart the unit?

Try a different LP tank too.

Well, I changed the tank and stared it up again.This time after the 1/2 hour it sounded like a change in fan speed but it didn't shut down. Its has been 12 hours now and still running. The 2nd tank took about 4 full turns to open fully, the 1st tank took maybe 3/4 to 1 turn.Maybe a difference in tank release pressure, who knows but it is working. For testing I set it up close to my home. Now I have to shut it down and set it up in a better location.I hope it restarts.Should I let it cool down before restating? . Now my neighbor wants me to fix his. My total cost New nozzle $10 w/ shippng, new regulator $17 home depot (can no longer use pressure reset tool), Plastic screw $.50, fun level about 5 out of 10. AGAIN THANKS FOR ALL YOUR HELP will keep you posted.

Shut down after 18 hours.Restart shut down after 1/2 hour. Seems that as the unit got full sun it shut down, maybe something is getting to hot.Will try to restart in a shaded area and see what happens.

Well For the past 3 nights the defender has worked from around 6 pm to around 11:30 am. Then it shuts down and will not work until around 6 oclock again.I think the heat of day is causing the unit to over heat and shut down. Does this sound possible? Could the circuit board be sensing higher heat and shutting the defender down? Anyone have any ideas? Does anyone have the circuit board figured out? Thanks for any help

Just a hunch, try the original regulator.

I was going to replace regulator with the original. As I was backing off the knob I heard a 'hiss', so I figured I would try it one more time. To my surprise it has been working since my last post. I also repaired my neighbors and his has been working since July 2. Thanks again for all your help. Keeping fingers crossed.