Hello everybody,

I have the dreaded no heat issue with my '97 VDP. I've pulled the aux heater water pump and the brushes were down to the wire pigtails, so I renewed the brushes. I'd made sure that the motor worked and spins by applying 12V directly to the pump's wires. And it spun like a top. However, when I'd put everything back together, the pump would not work. I had the heater temp controls at manual, hot/high, blower at face level, and recirculate interior air. I then waited for the engine/coolant to get hot. Once coolant was hot, still no heat, and no buzzing from pump. I then tested the connector leads (on the harness side, not the pump side), and it had zero volts. I'd check the fuses, and they were all fine. Does anyone has any idea what could be the problem? Is there a relay that might be stuck or not working? The air condition works great. But no heat. I did a search on this forum, and someone had the same problem, but it was never answered/resolved. I will appreciate greatly if someone has/can share a solution.

Thanks in advance.

By the way, I'd found some exact fit brushes from a company called www.carbonbrush.com/Arrowhead Electric Company Main Page. The brushes are 4mm x 4mm x 7mm long - they're tiny little brushes, and has a pigtail at the end. They are $3.25 each, plus $8.00 for shipping and handling. The stock number is L4-4HA. Here the webpage containing the brushes: Back- And Side-Shunted Brushes

 

Could be the heater core is plugged up?


Try and blast water in a reverse direction so it gets out nasty old deposit

 

Thanks for your reply, VDP408. I'll check to see if the core is plugged. But why would a plugged core cause no power to the aux pump? Not sure if they are interlocked, but I'm used to a more simple system than this.

 

I don't think a plugged core would stop the electrical pump from working.

There is, however, a heater pump relay that could be the cause. It is located in the engine bay in front of the air box. Quick test would be to remove the relay and jump it. If the motor runs you need to replace the relay. If not get your voltmeter out and start looking for a short/loose wire/bad ground.

 

OK I didn't read it correct. I read you took it apart and it worked but still.no heat.

Now I see its not working pluged in to car.


First I would follow alleng

Find the loose / short if there is one

If you can't find. Double check the relay.

If nothing works. Try pulling a spare pump and relay from junk yard.

I would still back wash the core.
I will make a DIY when I flush my coolant next month

 

Thanks AllanG and VDP408 for your suggestions. I have to prepare for a month long overseas trip, so can't get to the car right now. I will try your suggestions as soon as I return and will post results. All the best.