Interesting location. Should get more air then the driver side motor/tranie mount. Where did you get the resistor??

And, welcome to NAM.

 

ebay from uk as I live in Europe, stuff from USA are expensive with shipping and taxes.

I tested new resistor today in the morning in traffic jam (25 min), outside temp was 25 C (77F) and low speed fan kicked in 4-5 times, then when I stopped the car I checked resistor temp by hand and it was around 50-60 C so the aluminium plate with thermal grease helps a lot. So resistor is good, but I found coolant starts leaking from the expansion cap as temp goes above 104 C (219F), and stops after low speed fan cool down temp. Expansion tank and cap is brand new plastic Meyle. Should I add more coolant to mixture to raise boiling point a bit or check expansion cap? Mixture as I remember is -18 C (-0.4 F)

 

I took a big breath and successfully blow air via expansion cap with my mouth, so brand new expansion cap was crap, I bought a Febi one which is working fine now, low speed fan working no leaking around cap after temp goes above 105 C.

 

This helps me, as I have not sat down for hours to read 1300 posts about the low speed fan operation. The above post is a lot of help.

 

This is a good thread.

What year car do you have as wiring is different.

 

Shout out to louisut (post 867) for the helpful diagram and everyone else who researched this fix. Just installed the Mouser part on my 06 and got my low speed back! Thanks so much for the help.

 

Also completed this fix with the Mouser resistor tonight and A/C is blowing cold now.

Thanks to everyone for the information.

 

Thanks all for contributing to this thread. Got the resistor form mouser and low speed fan is working again! Low speed fan now kicks on at 221F and shuts off when temps get back down to 214F, as measured with a scangauge and in line with the bentley manual. No longer are engine temps reaching 234F, which is when the high speed fan kicks on.

Only word of advice i have is for those who have head lamp washers and placement of the resistor. If you're mounting it on the metal bar in the engine bay per the diagram many pages back, make sure it is not in the way of the headlight washer units. I didn't do this, and whacked my headlight washer module loose while closing the hood.

 

I just ordered the Arcol resistor from Mouser. I look forward to doing this project.
Many thanx to the contributors of this awesome thread.

 

Has anyone measured the amount of heat the resistor puts out. I checked mine it is around 160F. Is this normal, I know that the voltage drop / resistance produces some heat but I'm not sure how much.

 

I put the green amazon unit on and it was around 160 F as well. When you think about it, that is not really that much heat and if you have some good heat sink paste you can transfer that to what ever you are mounting the unit too. Would be interesting to test the resistor when it is not attached to anything for temperature.

 

See my post #755 and 758 761 763 on currents and power dissipation. I am concerned about that kind of temp on the resistor. Was this measured on a hot day, the engine running and the hood closed. I suspect the temp in that condition will be a good deal higher. Are you running without heat sink?? Not bolted to a metal body part with thermal paste. I went a bit overboard using a computer CPU heat sink and fan mounted in the pocket below the windshield. But I like projects.

 

I used a digital meat thermometer to measure. I mounted the resistor to the driver side motor mount with a heat sink paste. Your posts were usually celsius and us nontechies usually use fahrenheit.

On a hot day (90 F) upon opening the hood what temp would you expect to see.

 

The low speed fan current causes about 50 watts to dissipate in the resistor. The spec is 1deg C (1.6deg F) rise per watt on a good heat sink for the ARCOL 100watt resistor. So at 160F the motor mount was probably at about 80F. The calculation is: 50watts times 1.6F is 80 deg F rise, subtract that from the 160F measured suggests that the motor mount was at about 80F, this assumes that the mounting is truly flat and all 4 mounting feet are torqued down. Since you do have it on a heat sink you can expect the resistor to always be about 80deg F above the motor mount temp. Lets say you visit the low desert out here in California where I will be next weekend, at 112F ambient air temp the under hood could be 150 or higher, add 80 and you are at 230deg F. The ARCOL power rating derates in a linear fashion to zero watts at 392deg F(200C). That means at 392deg F it can safely dissipate only 0watts, yes no power can be dissipated at that temp. It is rated at 100 watts at 25C (77F). So it hits a dissipation limit of 50watts half way between 77F and 392F, thats 234deg F. So 234 minus 80 is 154deg F heat sink temp for maximum operating point. That may be where the motor mount temp might be in 112deg F weather. Sounds like yours will be ok.

 

I have found some temperature test strips but do not need 1000 of them. There is one out there that will turn color at 230F/110C..

I did some construction consulting for Cornell. Building had systems that were at 4 degrees K.

 

Well I bridged the red fan wires with an Arcol resistor. Checked my work and had a short on the low speed input now, (was open before) ...good to go, right?
Nope. Even with the AC on Max, the fan wasn't coming on. So I shut the car off and started to check fuses - with a DMM. They all checked good. So I figured I would fire the car back up and let it run for a while and see if the fan comes to life.
No bloody dice. It turned over but wouldn't fire. An exclamation point is now displayed in the steering wheel, and the check engine light stays illuminated. I tried maybe 5 times, no success, and now the battery is dead.

I am at work with no charger. 76 miles from home, Dammit!

Anyway, here is where I put the resistor:



So:
No AC
No fan
No start
Dead battery

I have a Foxwell NT510 on order - should have it by Friday

May have to see if the dealer will take the car back. This is ridiculous.


EDIT: A friend of the neighbor at my jobsite had a battery charger w 10 amp capability. I hooked it to my battery. Came back 40 minutes later, pulled the charger and hit the button - success! It fired up! I packed up quick and headed home, albeit withe windows down, roof open and heater on full blast (defrost). Made it home, left it running, and low and behold the fan (high speed) came on for a bit. Then turned on the AC - Max, and the low speed came to life! Went and grabbed a flashlight to look at the AC compressor, no dice there. Will need to get a clutch coil for it. (I did put some 134a in it, no change)

I then put it on my charger. And had to pick up my daughter for dinner tonight. Checked the voltage of the battery and it was 12.39. Should have been higher. It fired up and I went over to get her. While there I just left it running. About 3 minutes in the car shut off. Subsequent start tries, maybe 4 yielded no love. Put the fob in the slot, hit the button and poof, it started up. (headscratch)

Can a failing battery cause the car not to start?

 

In my experience, if the battery is less than 12v it won't start.

 

Thanx for the reply. I went and bought a new battery from Napa, exact same model. Installed it and it still just cranks, not even trying to fire.
When I get home from work today, the Foxwell NT510 should be at my house.

Although we are going camping in the Westfalia this weekend, hope to have some time to at least get a diagnosis.
My bet is that it is the low pressure fuel pump, as it runs like a beast, or doesn't run at all. None of the running crappy sans the turbo, unfortunately. It's a 2009 with 100,610K miles, in which the HPFP would be covered. Unless it has replaced already.

 

Getting this back on the topic. I have the gold resistor coming and once I receive, will measure up then I am going to get a heat sink and fan to mount in the windshield well as LAHills did.

 

new pump, new fans, no steering problem!

 

I would appreciate it if someone could shed some light. 2005 MCS all stock, I put in the new resistor and it still overheats at standstills and low city speeds. The resistor gets hot when I start the A/C so I know it's wired correctly and not blown. I am not an electrics guru so any thoughts greatly appreciated..

 

The low speed fan does spin correct? Overheat when AC is on and off? Coolant reservoir is at correct level? What are the signs of overheating? When did you change the coolant last?

 

I guess the low speed fan still does not kick in, this is why I did the LFSR mod. Overheats with A/C off, when A/C is on temp is rock solid. Temp gauge goes up, I have the chrono pack. 8 months ago, complete flush and everything.

 

The way the fans work are one sensor for temperature and another for the pressure in the AC lines. If you are not overheating with the AC on then it would be logical to assume that the pressure sensor is working. You are not getting any blow off only the temperature sensor gets higher? Where on the temp sensor?

Need some more info. Suggest you check out # 0017 of the below post and provide some temperatures. What temperature does the low speed fan kick in? The high speed?

https://www.northamericanmotoring.co...questions.html

 

No blow off. Temp needle keeps going a bit from north reading where it usually sits, I have not taken temp readings. When the A/C is on the temp gauge is pointing north rock solid.
Point is, nothing changed since I put in the resistor, it's behaving exactly same as before.
I think it is related, my A/C, when on cold, it briefly blows hot air 3-4 minute after I start the car. This happens exactly the same before and after the resistor mod.