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If memory serves the heater will drop out at around 10.5v, similar to fridge.
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There was a thread recently about accessing and ultimately replacing the batteries.
Here we go: https://vwcaliforniaclub.com/threads/92-california-battery-replacement-advice.12543/
Worth sticking them on charge for a few days. They may just be flat
Hi Pod. Just started working on a default heater on our '93 T4. Green ligt comes on, fan starts spinning (both on heat-mode an fan-mode). I've re-soldered the control module so that should be fine. Not sure if I should se the red light come on?Right, as Dan says, there are two bits of electrical kit behind the fuse panel cowl (behind drivers seat).
One is a power relay that seems (I've never really got to the bottom of what it does) to supply the main control module. The power relay is fed from the main fuse panel below the steering wheel.
Both of these click loudly but not continuously.
I had a control module fail (now obsolete) so I opened it up and there is a power relay inside on the PCB. The point is it does make a loud click.
This relay essentially powers up the glow plug (I assume we're discussing a diesel heater here?) which runs for a time period (15 seconds?). The dosing pump then fires in fuel and away it goes. The heater does run for about 45 seconds before it goes into heat/blow mode. You'll hear the tone change.
Failure to start could also be a problem with the control panel in your photo. This basically puts power into the control cct of the control module.
I've been round this loop with mine (and many more) so happy to help with diagrams/advice etc.
It will take some methodical voltmeter action!
It could be the power relay at fault so bypassing/testing that would be a good place to start.
Apparantly only 0.3-0.4 volts going to the plug..I’d get under the van and check there is 12 v at the glow plug top. Voltmeter, red onnthe gkow plug top, black to van chassis.
If yes then whip the plug out and put a 12 v supply to it to check it heats up. 12v + to the connection at the top, 12v - to the body of the plug.
Be careful, if it’s working they get very hot.
Get back here and report once you’ve done this.
Yes, heater was switched on. Not sure about the window but I'll def. have a look. Took of the panel by the drivers seat to get a hold of the control unit.. I'm pretty sure I'll be able to get a hold of a new (used) one here in EU if it turns out bad..You were testing the plug with the heater switched on? Daft question I know but if it times out on a failed start then you won’t see voltage at the plug.
Well I hope so. The next thing to test is that you have power /run signal to the control box from the switch unit.Yes, heater was switched on. Not sure about the window but I'll def. have a look. Took of the panel by the drivers seat to get a hold of the control unit.. I'm pretty sure I'll be able to get a hold of a new (used) one here in EU if it turns out bad..
Any news on where to look next?Well I hope so. The next thing to test is that you have power /run signal to the control box from the switch unit.
I’ll post a snap shot of the wiring diagram tomorrow.
Just checking, you do have healthy batteries? Less than 10.5v will not allow the heater to start.
Has been plugged on mains at all times while testing - as for the same reason..Been quietly watching this discussion and was about to ask the same thing. You can hook up your Westy to the mains and try your heater as this will bypass any battery low voltage issues.
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I will check the other connections/wires in a couple of days and come back!My thinking is a bad earth. The OP is seeing less than 0.5v at the glow plug.
It should also be noticed than the heater hasn't been fired up in at least 10 years! Previous owner never used it...
No 12V at pin 1. Fuse inside the control unit was dead. Other fuses are good. Red wire? The only red wire from the control unit (pin 4 which has 12V) goes to the main fuse?If you have no 12v at pin 1 then the next step is to check the start signal from the ventilation switch panel to the control unit.
This is a red wire. In the rear of the ventilation switch panel check there is 12v. You should also be able to trace this back to the control unit.
If this is good then the problem is inside the control unit.
Sorry I meant red wire from the switch panel over the sink to the control unit.No 12V at pin 1. Fuse inside the control unit was dead. Other fuses are good. Red wire? The only red wire from the control unit (pin 4 which has 12V) goes to the main fuse?
Sorry I meant red wire from the switch panel over the sink to the control unit.
Check this live when you select Heat On.
If not then it could be the switch panel.