Propex Heater

[steveo9007]

These pictures were screenshotted from video which you should watch




notice the battery pos and neg cables spliced into the 4 way connector block.

[t3convert]

to 937 carrera
I am up against a number of problems here. First of all the only supply cable at the heater end (which should be the one coming from the thermostat) comprises only two wires, a red and a black, which are somehow connected to the four (including the purple and orange) going into the heater box. So I don't really know where this 2 wire supply cable comes from. The only place where I can get access to any wires to check where current is present is the Labcraft unit. I've tried revealing the wires behind the carpet material at the back of the unit but they're all grouped into black cables. Maybe you could suggest where I could put the multimeter probe on the terminal block inside the Labcraft.

[937carrera]

The red wire is the 12v supply from the labcraft.

The black wire is an earth, can be connected to the -ve on the battery or chassis. That's the easy bit, these are the wires that need to be spliced in.

Steve9007 was the one that noticed the orange and purple wires tucked up out of the way from your earlier picture. They need to be connected to the thermostat, so either have a poke around and find the ones from the thermostat, or go from the thermostat end, find the 4 wire loom and follow where it goes.

To be hones, i don;t think you need to do the latter, as it's quite possible that the orange / purple wires are already near the connector block because the thermostat is showing a red light when you switch it on, so it is getting power.

The screenshots above from the video should be a big help too



Only you can find where the cables are on your van though......

[Oldiebut goodie]

to 937 carrera
Sorry to be continually keeping you waiting. I've had other unrelated stuff to attend to again. I re-checked the wires at the heater end with the thermostat on full and the leisure battery connected up but still no juice is coming through. So I thought the next port of call would be the wires at the back of the thermostat but I couldn't get the casing off. I looked in the Propex manual as you suggested (page 5/6) but it shows a slightly different casing and mentions screws in the lid with caps covering them - none of which I could find. The casing I've got is the one in the photos I posted on June 10th. Have you any idea how it comes off?

To access the inside of the thermostat - prise the knob off with two stiff feeler gauges across the diameter ( saves breaking it as it is delicate ) and there is a screw underneath.

[t3convert]

to oldiebutgoodie
Thanks a lot. I may need to prise it apart. But first I'll take a look at the video advised by 937 carrera

[t3convert]

to 937 carrera
The videos were very useful.
When I next get some time I'll hunt for the missing orange and purple wires from the thermostat (they may be lurking at the back of the fridge somewhere).
If after an extensive search I can't find them then I'll take the casing off the thermostat (oldie but goodie explained how) and run 2 new wires.
However, the original mystery still remains because there should be 12 volts in the red wire when the thermostat is switched on and on full.
So it may be necessary to run a fresh red and black wire all the way aswell.

[t3convert]

to 937 carrera and Steve9007
Despite a comprehensive search behind the fridge (and everywhere else) I couldn't find any other cables. I can only assume that the remaining bit which connects to the heater has been deliberately disconnected somewhere along the line and removed, probably behind the Labcraft Unit. I thought the easiest solution would be to run 4 fresh wires from the thermostat direct to the heater so I removed the thermostat cover (thanks Steve!) and this revealed 4 terminals: a red wire goes into the top one and it shows 12v with the thermostat switched on. Another red wire goes into the 2nd terminal from the top but this shows no voltage. No wire at all goes into the third terminal (should there be one?) yet it shows 12v with the thermostat switched on. The bottom terminal contains the two black wires which accompanied the red wires going into the top two terminals and is negative. Assuming that the top terminal is the live from the leisure battery and the bottom terminal is the earth how do terminals 2 and 3 connect with the orange and purple wires at the heater end? Please see photo of the thermostat (hopefully attached)

[steveo9007]

Found a couple of pics, your wires from the heater box should have 4 wires, obviously red and black speak for themselves, the orange and purple wires are for your control of hot air and cold air as your switch on the thermostat is a 3 way switch, left is hot air, middle is off and right is cold air.




so you defo need the wires the orange and purple to be connected or else you aint getting nothing out of your heater as the controller with the wires not connected won't know when to switch the heater on or off, if you can't find the wires then you may have to run new ones.

[Oldiebut goodie]

Different thermostat!

[steveo9007]

Different thermostat!

Surely the orange and purple wires are signal wires from the heater to thermostat so if they connected to the 2 middle terminals the wrong way then it would affect the switch so it would be a case of reversing them to get the correct heating when switched ??

[Oldiebut goodie]

Not necessarily - wiring diagram is usually inside the top. Orange is likely to be switch on of heater and blue switch on of ventilation. Not normally signal wires on a crude thermostat like that just power. If they were signal you wouldn't need the relay on the board.

[Oldiebut goodie]

t3converts pic shows normal connection for heating with no ventilation provision - I hazard a guess that the switch on his is purely an on/off switch.

E D I T: have gone back to his earlier posts - his IS purely on/off.

[steveo9007]

ok well i don't get this then. as they say on dragons den, I'm Out leave it down to you guys to sort

[937carrera]

ok well i don't get this then. as they say on dragons den, I'm Out leave it down to you guys to sort

Naah, you know just about as much about this as any of us.

The thermostat is a simper one...... it just lacks the cool air only option, so who cares, the electrics are probably the same either way, it's just that the fan only option wouldn't be connected on the thermostat end.

The OP needs to go back to page 5 of the installation instructions. If the wires aren't there, then they need to be created, in compliance with the wiring diagram, quite simple really. Remember there are 4 wires at the business end where the heater itself is. Given that Propex area really helpful then a quick call to them will probably yield a wiring diagram for the simpler thermostat ??

I think the OP should unscrew the thermostat off the wall and follow where the wires go. It's possible the other wires are tucked out of sight, just like the ones at the heater end ???

[steveo9007]

yep agree with that aswell, from the propex box itself the 4 wires have to go to somewhere even if they have been snipped right at the end to where they have gone they should be there, agree with you in the OP needs to investigate more and yes behind the thermostat, them wires need to be known where they go. And there has to be some form or control over the propex heater other than just a +ve / -ve. I guess only he can work that one out in his own van now.