Question as Titled...

Recently reconnected my AWP with a fuse, and it does not appear to be working with the engine warm and the heat on full blast. When I connected it directly to power, it worked fine...


Just checking this thing out, not getting a lot of heat when it is below freezing.

TiA

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1998 VW Cabrio
2001 Audi SomeRoad A/T (no air suspension)
2003 Audi DeadRoad M/T (no vroom, for later)
2002 Audi NoRoad A/T (nothing under the hood, being rebuilt)

I thought it was supposed to come on when the Heater is on. But, there is 3 different types of climate control setups.

But, there is some old threads that say if the Aux Water Pump shorts out there is no fuse in the circuit and it burns part of the climate control controller inside of Car. That in fact is believe to have case one fire that burned a Car and I think it was 2 other scares due to smoke from the burning.

There was a discussion on what amperage of fuse to put into the circuit.

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84 300D, 82 Volvo 244Gl Diesel

The aux pump is powered from the climate control and is not fused in the 123. The pump runs whenever the climate control is in any mode except OFF.

Power to the pump turns it off (closes flow of hot coolant). An unpowered aux pump defaults to wide open, full flow of hot coolant.

My understanding, is that it was installed as customers were complaining about low heat at idle. I know mine is on, every time the heater is on. But I have the ACCII which as stated is one of three different ones used....

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Sorry, but no... You have confused the mono valve and the Aux heater pump here. Power to the pump causes it to circulate coolant.

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2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

So, the mild concensus is that it is on when the temperature is being modified, warmer Or Colder...

Pretty sure mine is the last system; blower comes on very slowly if put in Auomatic.

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1998 VW Cabrio
2001 Audi SomeRoad A/T (no air suspension)
2003 Audi DeadRoad M/T (no vroom, for later)
2002 Audi NoRoad A/T (nothing under the hood, being rebuilt)

Go to the service manual for the type of system you have. There is a complete check out of every function with what door is where, if the AC compressor is on, if the aux water pump is on etc.

I believe it should be on whenever the climate control is in any position other than off. You have the ACC III system since yours is an 1983 model.

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2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

Dude99 is correct. The aux pump is powered whenever the climate control is ON but the monovalve is open or closed as heat is called for. The electronic controller send ms a proportional pulsed DC voltage that closes the valve until the hot coolant flow gives the correct temperature. If the voltage is missing due to some failure, the monovalve defaults to wide open. Coolant can flow through the aux pump whether it is powered on or not but obviously you get more hot coolant if the pump is running.

so if we have low heat at idle but the monovalve is fine, should we suspect a faulty aux pump?

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1981 NA 300D 310k miles

It would be my first port of call. They are a very common failure item.

What kinda berries?

I only have raspberry problems......

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If it is bad, I wouldn't even consider replacing it since people ask >$100 for used ones. Besides potential electrical failures, they increase the risk of coolant loss (could lead to a damaged engine!). I removed them on both my 300D. One had a leaking seal (slight coolant spray/mist) and the other appeared fine. I replaced w/ a length of 5/8" heater hose. I used silicone which is more flexible and helped fit the different sized fittings, plus lasts much longer. Another option is one guy here installed a W124 "mono-valve" where the aux pump sat, since those are cheaper and easier to source than in our cars.

I haven't noticed a loss of heat without the aux pumps, but the climate system has enough other quirks to make with & without a tough call anyway. If I drove up in the Sierras, I might notice a "less heat at idle" issue, but I wouldn't risk my diesels up there. I don't want to test starting in 0 F temperatures.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

On my 1979 300D, which used the admittedly different servo based ACC II system, I had very poor heat at idle without one.

*sigh* damn auto correct

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2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

The AUX pump, can also be taken apart...Cleaned and bearings re greased. As long as the screws aren't rusted/corroded....I did this on one and haven't had any issues...

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