Now that the weathers gone cold i seem to be having probs with Volvo heaters in FM/FH 12s. It seems no matter what i do, which setting or air con on or off, i can only seem to get ‘furnace’ or ‘cold’.
I have to set the temp to its hottest, then when it gets too hot i click the temp down just one notch, which results in cold air being blown out and within a few mins i’m clicking it back up to hottest. I’ve driven a couple of trucks where i’ve spent the entire night adjusting the heater every 10 mins, which is a complete PITA and completely unsafe.
I’m guessing that it’s the type with the rotary knob.
All you have to do is set it,and then leave it.After it has got up to temperature,it will cool slightly before shutting off,hence the cool air coming from the outlet pipe.Cool air also comes out of the pipe when it starts up,before you start to feel heat.
Hope that makes sense,and that is my experience of the ovloV night heater.
Sounds like the cab thermostat is knackered, it should just cut in/out as required. It’s probably an eberspacher, not a lot to go wrong with them. I used to have an FH12 and always found it very reliable. Without knowing which model you have (probably a D1LC) I cant be more precise. However use this link, go to ‘Air Heaters’, and you can look at the manual.
Ah, no, no, I obviously didn’t explain myself clearly, sorry.
I’m not talking about the night heater, i’m talking about the trucks normal heating/air con/ventilation system.
The temp is set by a rotary dial, numbered up to 26, with another notch before the max setting indicated by a red square. I’ve been having to have the heat set to the red square, then when it gets too hot i click it down just that one notch above the 26. Then 10 mins later the cabs gone really cold so i have to set it back on the hottest, and in some trucks i’ve been having to do this every 10 - 15 mins throughout an entire shift.
I’ve tried setting the temp at 22 or 24 and i’ve tried with air con on and off, tried setting the fan to different speeds, everything i can think of basically. I can’t help thinking i’m doing something wrong, but i’ve never had difficulty setting the heater on any other vehicle before.
In the summer there was no prob, set the air con to 22 or so and that was it. But its cold now, so i just want some steady, regular heat.
Sounds familiar. We’ve got one “facelift” FM with the aircon, standing joke is that it’s actually an ERF heater… Either Roasted or Frozen!
At least they don’t “fog up” as much as the older ones do, only way to clear them quick was to drop both cab windows and freeze for a minute!
Oddly the old FL10 (we’ve got two of them as well) never seems to suffer from this; presumably the draught from the rubbish window seals keeps the glass clear.
How old is the vehicle, or rather, how knew is it?
The knob with the numbers up to 26 should indicate degrees. 21 is normally about right. There should also be Auto settings on an additional knob(s). Set to Auto and it will maintain temperature.
The only time you need to change to manual is when changing trailers as, with the door opening and closing, the temperature changes will cause it to go into ‘overdrive’ trying to keep an even temperature, which, when you are continually climbing in and out, and probably warm anyway, is something you probably don’t want.
How old is the vehicle, or rather, how knew is it?
The knob with the numbers up to 26 should indicate degrees. 21 is normally about right. There should also be Auto settings on an additional knob(s). Set to Auto and it will maintain temperature.
The only time you need to change to manual is when changing trailers as, with the door opening and closing, the temperature changes will cause it to go into ‘overdrive’ trying to keep an even temperature, which, when you are continually climbing in and out, and probably warm anyway, is something you probably don’t want.
Nope, having the other dials on auto doesn’t help either.
I’ve suffered this on a number of vehicles, 2 of them being worse than others, these 2 vehicles belonging to 2 separate companies.
I guess the 2 trucks were a bit leggy, the one t’other night having 700,000 kms on the clock, the other one 5 or 6 hundred thousand.
Is the prob indicative of a pollen filter or summat being blocked?
It’s the climate control . It won’t blow out hot air all the time , it maintains the heat you have set the dial to . You are getting used to the heat and then because you are a cold arse starting to get chilly again .
paul@midway:
it maintains the heat you have set the dial to . You are getting used to the heat and then because you are a cold arse starting to get chilly again .
Thats not the case though. Honestly, i’ve had cars for donkeys with air con, and you rarely touch the settings. Even on trucks without air con once you get the tempeature right you rarely need touch the heater again.
Its only with Volvos. Had one last night (which broke down at J13 on the A42 for a couple of hours), and whilst it wasn’t the worst, i was still having to click between hottest and 26/26.5.
In fact, i’ve never ever driven any other vehicle where any setting below 26 is too cold. Even my old Pug 306 diesel, the air con would remain at 22 pretty well all year.
To be honest with our fleet of Volvos I have never driven one yet that is blowing cold , they keep the temp up fine .
All 56 -57 platers .
Some of the hired stuff we have had in the past from volvo has been ok whilst some others have not been brilliant . Anything between 53-06.
It’s either a crap or blocked heater matrixs or bust thermostats .
Probably a common problem .
A different problem here but still volvo, my 00 fm’s heater jammed on hot and window setting about a year ago. Volvo ireland wanted 1800 euro for the part alone plus3 hours labour. I declined this tempting deal as i knew a change was a comin. Unfortunately the truck was like a greenhouse all summer and in autum the fan speeds all packed in aswell. Roll on january 08 ,so i can stop wearing my motorbike trousers when im drivin’
