Right, you know when you switch it on, it fires up and after about 10 minutes it drops down to a tick over? Well mine isn’t dropping down. It just keeps on pounding away at full blast til I have to knock it off or I’ll start cooking.
The temperature dial is fully down, although I’ve tried it in all positions. Any ideas? Thermostat? Faulty dial? Or something else?
Both inlet and outlet vents are free from dust. Oh, and I’m in a Volvo.
Had exactly the same problem with the 59 plate fm i drive,turned out to be the thermostat control wasnt picking up any heat in the cab and was going for it full bore all the time it was on…new switch fitted on service and now it right as rain 
is the little round mesh temperature sensor near the thermostat dial blocked? if it is then the thermostat wont know what the temp is and keep blasting away
Yes, the first thing I would check is that the thermostat vent isn’t blocked with dust.
You could always go retro, switch it off and use 2 sleeping bags and wake up with your foot frozen to the side window.
Thermostat vent clean as a whistle, so it’s probably the switch like washy says. Cheers for the replies fellas.
Mike I do switch it off and I do wake up at 3.30 with my foot frozen to the window! So I knock it back on and wake up at 5 done to a turn. Can’t bloody win!
I have the opposite,mine will kick in for about 5mins then stop won’t go again until I switch it off and back on again,all the vents are clean too…any ideas■■?
Sorry for hijacking your thread,but does any body drive a merc axor?
the night heater on mine only stays on for a maximum 118 mins ,is there any way of changing it or over riding it?
if you dont want to fill this thread up .please feel free to PM me thanx.
calebs gramps:
Sorry for hijacking your thread,but does any body drive a merc axor?
the night heater on mine only stays on for a maximum 118 mins ,is there any way of changing it or over riding it?
if you dont want to fill this thread up .please feel free to PM me thanx.
I might be completly wrong but i think i remember someone telling me that you have to have the key on the first click to keep the heater on all night. Like it said though, I could be totally wrong and I’m sure someone will correct me. 
Ah right ,cheers for that Paul,gotta be worth a try and il let you know when i find out ,thanks again.
mike.
Thetaff:
I have the opposite,mine will kick in for about 5mins then stop won’t go again until I switch it off and back on again,all the vents are clean too…any ideas■■?
Sounds like it’s overheating. Pop the outer covers off it and blow off the fluff/dust/■■■■■/wool from around the heat chamber and circuit boards etc. Also check the plug, you might need to whip it out and give it a quick wire brush (or Bennetts toothbrush) 
Quick fix to try, fire it up and stuff your curly air duster thing up the narrow combustion inlet pipe and blast it. Sometimes enough to clean the internals out if they’re gummed up with soot etc. I have also solved this by squirting easy start (other flammable aerosol products are available) up it once it fired. Do stay away from the exhaust while doing this
Once you get her going leave it on full balls with the windows down for an hour to give her a good throat clear. 
Thetaff:
I have the opposite,mine will kick in for about 5mins then stop won’t go again until I switch it off and back on again,all the vents are clean too…any ideas■■?
Needs a new thermostat switch, mine was doing exactly the same, it would roar for 5-10 mins and do nothing until you switched it off and back on.