I do not have heat in my car so I removed the heater pump. Sure enough the brushes were worn down to little nubs but still appeared to be able to work. I was able to recarve some larger brushes to fit but the motor still doesn't run, I get a zero resistance measuring from the plug end. It seems like a direct short when I apply 12 v to the terminals. Could the diode in between the brushes gone bad? (The heater coils flushed out well)

 

When I trace the wires back and remove the diode from inside the motor it reads about 3 ohms. Should I be able to run this motor just attaching 12v to the plug conector? I am not getting power out of the cars wiring plug. I can't find a mention of the fuse for this pump. Where is it? Does this pump run when the heater is turned on? Does it wait untill the car gets up to temp? It 's Canada, it's winter, it's getting cold, I need to fix this as soon as possible

 

Hi Tilbury - sorry the only limited answer I have for you is that as far as I am aware the pump will be working as long the "fan" is on - and this is regardless heat or AC. I also have a no heat situation for second winter in a row. Last year, I fixed by unclogging my core. I had replaced my pump but turned out the old one was working. This winter (well, I'm in TX and don't really need it just yet ;-) I am facing same issue again but did not check my pump yet. So don't know just yet if I need to unclogg the core (again!) or pump died.

Cheers

 

I'd get a used ebay pump. A spare is handy to have. You can plug it in to test without hooking up all the hoses. I found a guy on ebay that even repairs them.

 

I changed the diode in the motor to something I found on an old circuit board and it works on the bench. However hooked into the wiring harness it still doesn't turn on even after the engine is warmed up. I checked the 10 amp fuse in the 15 slot on the front fuse box and it was good. Changed it anyway to be sure. What can I try next?

 

I have to set my climate control to 80 degrees to get adequate heat. Then it blows nice and warm with good volume. Is this typical? Where is heater pump and what is part number?

 

The heater pump, also called the auxiliary water pump is sort of under the header tank and in front of the brake master cylinder. I have mine out at the moment waiting for new brushes. They are crazy expensive and I didn't want to get a used one figuring it might not be much better than mine. Part number is MNC6710AC.

 

I don't know if the fuse you changed was fuse number 3 in the larger of the engine compartment fuse boxes, but that is the fuse that controls this pump. It is not listed as such, but it is the correct one. It also controls front fog lamps, and the intelligent sounder among other things. As I remember, there are 18 slots in the smaller of the 2 boxes, and 22 in the larger, which is the further forward of the 2.

 

If that fuse is good and the pump works on the bench then check the heater pump relay, could be defective.

 

No luck changing the fuse or the relay. Both were good but I did swap the fuse out and the relay swapped with the fog light relay with the same result. I'm getting ready to wire it into the headlight wires so that when the car is running the pump will be on.

 

Before you start to change the wiring, check the input voltage on pin 1(supply side of the relay) and pin 3(supply side of the relay contact).

This will tell you whether you have wiring fault on the power side or a problem up to the A/c control module.

Maybe also worth checking the connectors along the line if you haven't already done so.