Carver P4 heater (How can I get to it)

[Dovie]

My friend has Peugeot Autosleeper Harmony which is fitted with a Carver P4 Gas space Heater. Does anyone know how to get to it for servicing, It starts up and runs for a few minutes pushing out hot air and then goes off and the green light turns to 2 red flashes.
The fault finder chart shows, cause is blocked flue or intake or combustion motor or fan proving failure but can't see how to get to it.
Any Ideas would be welcome, thanks in advance.

 

[St3v3]

I'm assuming you've checked the flue in/ out under the van first? There is a gauze on the end of them that could be blocked.

 

[Dovie]

Yes thank you,
I have checked the flue in and out flue just in font of the wheel arch, I put vacuum cleaner on it and gave it a suck and blow. I have recently had the water heater out (due to a leak which turned out to be the hot tap jubilee clip behind kitchen sink being loose, but that's another story) and can see the heater but cant see a way to get to it, I would have thought that there is a removable panel for access.