SHC35 heater starting problems

[Cantineaux]

Hello everybody,

Im currently struggling with my SHC35 Hunter heater.
I recently build a new battery for my heater as well as a European usable fuel can as these parts are not buyable in BELGIUM.

When I connect my battery pack and put the ON/OFF lever on, the light turns green and after a couple seconds all the lights jump on for a short moment together with a beep tone. After this nothing happens anymore.

Am I doing something wrong or should the system do something different normally ? I read in the manual that the fans should turn on for a brief moment but this also doesn’t happen.

( when I put the control Nob to 0 the light of “At set point “ turns on and I hear some strange sound coming from the combustion air blower area)

For the battery pack I used 2x 12v battery’s of 7,5Ah connected to a molex connector I used the green and white cable for 1 battery and the black and red cable for the second battery I used the battery charging adapter to find out where to put the + and - for each battery ( I am not sure if these needed to be different for powering the glow plug )

I also have the 2 white wires connected to the connector for if I ever want to put a heat pad ( currently no heat pad attached )

The 2 brown wires go around in a loop connected to a fixed resistor ( to fake a positive 25°C temperature )

Can anybody help me out or tell me if I did something wrong as i don’t know how the machine should operate in normal conditions

Thanx in advance


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[ZiggyO]

After the initial beep and flash of all the lights, you need to leave it on and wait for anywhere from 30 seconds to 2 minutes for the glow plug to cycle and the fuel pump to kick on...... it may take several start attempts if there is even the slightest amount of air in the system..........

Z

 

[Cantineaux]

After the initial beep and flash of all the lights, you need to leave it on and wait for anywhere from 30 seconds to 2 minutes for the glow plug to cycle and the fuel pump to kick on...... it may take several start attempts if there is even the slightest amount of air in the system..........

Z

Ok thanx a lot !! I Will try it for a couple times.

I purchased it from an American army auction in the Netherlands where the heater probably set for a long while . it only had 180hr of working time on the timer so I don’t think there will be any parts broken hopefully.

Is it normal that it makes a buzzing sound when I put the control knob on 0
( I looked again to be sure and it seems to come from electronic control system somewhere )


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[njjeeper]

Im not sure if you ever solved this but I have the same exact problem. 2 heaters were working when put away 3 years ago. Now I have the same issue you described above. The main odd symptom is the buzzing from the power control board relays when you turn down the set knob. I have swapped batteries, main control boards, remote boxes and remote cables with ones from known good units. The symptoms don’t change. I have unplugged each fan, glow plug, fuel pump, etc and tried with the same results. The only board I don’t have a spare to swap in is the power board. If anyone has any new ideas, I would love to hear them!

Ok thanx a lot !! I Will try it for a couple times.

I purchased it from an American army auction in the Netherlands where the heater probably set for a long while . it only had 180hr of working time on the timer so I don’t think there will be any parts broken hopefully.

Is it normal that it makes a buzzing sound when I put the control knob on 0
( I looked again to be sure and it seems to come from electronic control system somewhere )


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[ZiggyO]

Take the handle end of a screwdriver and lightly tap the relays on the power board--- is it not common but being electromechanical relays, they have been known to stick as well.

Z

 

[njjeeper]

Take the handle end of a screwdriver and lightly tap the relays on the power board--- is it not common but being electromechanical relays, they have been known to stick as well.

Z

Figured I would post the solution for the next guy. I started with the relays that Ziggy mentioned in the beginning when I first had problems. I de-soldered them from the board and checked them with a battery and a meter. Both worked. One relay controls the power to the fans and takes signals from the control board to switch them on and off. The second relay only manages the TEG, and clicks from charging to running off batts. With both relays bench tested, I reinstalled them and had the same issue. Control box beeped with all lights lit, then nothing unless I turned the knob back and then the relay would buzz. After tracing the circuit and mapping the board, I kept coming back to the relays. Then ziggy confirmed again that they stick so I took a gamble and pulled the fan relay and replaced it with an off the shelf SPDT relay. It worked. Then I swapped the other relay with a new one, and it charged. Bottom line, those relays are trash and don’t hold up. I think the bench test worked on the original relays because there was more voltage when I applied power direct to it and it overcame the weak contacts. Fun fact, there are 2 more of these crap relays in the ignition box so if you have a bad ignition box, crack it open and replace them. I did it with my bad spare and it worked again.