06 Sprinter, need help diagnosing a few problems.

[The Enemy]

Just as the title states the aux electric fan, the ac compressor and the right half of the hvac lights won't work. Went to turn on the AC a few days ago and all I got was hot air. I also noticed that the blower position dial doesn't light up, but the heat/cold dial is lit up. The other thing that was happening was I only got air blowing out when I spun the pin wheel to the #4 position. Remembering this happened before, I swapped out the blower module with a new one and I got the fan to work on all 4 speeds but still have the other problems.

Today while heading south towards New Orleans I noticed that going thru the hills in KY the temp would creep up to 220* degrees and stayed there while driving at 65 mph. The temp needle was at the top of the 1 of the 180* mark. All this while I didn't hear the Auxiliary electric fan kick on. The outside temp is about 85* right now.

These 3 problems lead me to think there is something electrical going on that is affecting all of the components. Anyone have an idea on what could be going on so I could attempt to fix it myself of have an idea before I go to a dealer. My main concern is the Electric fan, but would also like to fix the AC as I am tired of sweating and riding with the windows down, its reaking havoc on my ears and sinus.

Thanks,

Nick

 

[Turtle]

No aux fan sounds like a fuse, or a multifunction relay, probably under the seat. Check the fuses first, then the relays. The right half of the lights sounds like a fuse, but then again those bulbs burn out on their own, as well.

Fan working only on high speed is a classic blower resistor module failure. There are a few other things which can cause the fan motor to run only on high speed, but this is the most likely cause and is the easiest to check. The resistor module is on the heater fan shroud, just under the hood up front, left of middle. It is black plastic with 4 wires coming out. A green wire, a yellow wire, and two wires that are white/yellow/black mix. It's NOT the one with Red wires coming out of it.

Disconnect the harness plug, little tabs on each end must be pushed in while plug is pulled up. Then on the right hand side there is a tab that you push to the left. This will release and slide the resister module to the left about ½-inch. The resister module will now come up (top away from you to clear housing) and out. From the Service Manual: with an Ohm meter set to R1, the needle should deflect far right or show 1 to 5 Ohms between any two terminals, if any two are an open circuit (no movement or reading) the resistor module is bad. Part # 05133432AA, will run you $35-$50.

If the circuits are all closed and the module isn't bad, then it's a multifunction relay, or the ATC (Automatic Temperature Control) unit on the dash (the one-piece unit on the dash where the three temp/fan/AC knobs are). The ATC is about $350, IIRC, and is both at the same time easy and a PITA to replace because you have to take all that console trim and the console out to get to it, but once that's done it's just a few piece of cake screws and electrical connection to swap it out.

The blower fan could also be as simple as the fan itself is going bad, which is what happened to me at around 180,000 miles I think. It's a 4-screw replacement and will cost about $200 for the replacement fan/motor.

Any or all of the above may cure the no-AC problem, or you may just be low on Freon.

 

[RLENT]

No aux fan sounds like a fuse, or a multifunction relay, probably under the seat.

Yup - try the big (possibly green) AT style fuse on the fuse panel on the side of the driver's seat pedestal. Be aware that the fuse may look fine (not blown) when in fact it actually is - a friend ran into this - I had told him to check that fuse and he did, reporting that the fuse was ok because it looked ok ....

I suggested that he check it with a multi-meter and he found it had no continuity .....

Only way to know for sure whether it's good or not is to check it for continuity with a multi-meter or continuity tester.

Otherwise it may be a relay, as Turtle suggests.

Check the fuses first, then the relays. The right half of the lights sounds like a fuse, but then again those bulbs burn out on their own, as well.

If one lightbulb works and the other does not, it is undoubtedly the bulb and not a fuse - the two bulbs are not fused separately.

The bulbs are a small bayonet style which fit into a small light green cup style holder (on an '06 at least) which are on back of the Automatic Temperature Control unit.

They can be replaced without entirely removing or disconnecting the Automatic Temperature Control unit - leave the control cables for the air routing doors connected and flip the ATC unit over to gain access to the rear side, and then use a pair of needle nose pliers to twist the green cups about 1/4 turn to release them and then lift them out.

I have replaced both of mine which had burned out.

However, there are some clear plastic parts which are used to transfer light from the bulbs to individual items in order to illuminate them - it may be that one of these has come loose and is not transferring the light to the blower position dial.

The bulbs are a couple of bucks apiece at the dealer.

Fan working only on high speed is a classic blower resistor module failure. ..... Part # 05133432AA, will run you $35-$50.

While you may wish to replace the resistor immediately to get your fan back, you also might want to hold onto the old resistor pack - if you are handy with a soldering iron, it can be repaired for a couple of dollars with a thermal fuse available from Radioshack (the following p/n data is from a friend):

270-1321 ITS IS438F(226C) RADIOSHACK

Alternatively, you can use a paperclip to jump the fuse and get it working immediately (see attached photos at the end of this post)

The blower fan could also be as simple as the fan itself is going bad,

It is possible that the fan may causing the resistor to go bad (excessive draw), but if the fan is only operating on 4, the resistor is likely bad (as well as the fan)

 

[Turtle]

It is possible that the fan may causing the resistor to go bad (excessive draw), but if the fan is only operating on 4, the resistor is likely bad (as well as the fan)

Yeah, I know, but the reason I brought it up is when my fan went, it was the classic symptoms of a bad resistor, it would still work on 4, but not on any other speed. But the resistor checked out fine. I replaced the fan, still have the original resistor in there.

Still, if mine started doing the same thing again, first place I'd look would be the resistor, since that's the most likely cause.

 

[RLENT]

Yeah, I know, but the reason I brought it up is when my fan went, it was the classic symptoms of a bad resistor, it would still work on 4, but not on any other speed.

Interesting !

 

[Turtle]

I never had the blower motor checked out, but my regular mechanic said that sometimes as they begin to go bad, it takes a certain amount of current to make 'em move. Dirty, crudded, corroded, or as the bushings go bad the last time the fan stops it stops juuuuust a little out of line and it takes more current than normal to get it going.

I had something similar happen to the blower motor in my first soccer mommy van, where the van wouldn't work, but if I got out on the highway up to speed, and then crack the window a little, the sudden change in pressure was enough to jump start the fan, and after that it would work fine on speeds 3 and 4. Next time I started up the engine, it might work fine, or it might be quirky again until I got up to speed. Just depends on how it aligned up when it stopped rotating.

Of course, every time I took in to have them look at it, it worked perfectly.

 

[The Enemy]

Guys thanks for the replies. I changed out the blower motor resistor, and kept the old one. Rlent thanks for letting me know about the radio shack resistor fix, will get the old one fixed up. As far as the big green fuse under the seat, I found it and pulled it out and you were right, it looked ok. I don't have a multimeter with me so I will go to the auto parts store and get one tomorrow and probably pick up the fuse if they have it there. Probably pick up an AC pressure gauge to see if I am low on Freeon. I know that when I used the AC in early January while we were in Cali, it didn't seem to blow as cold as it used to, so maybe that will be the problem. Only time will tell, hopefully it will tell me tomorrow.

Turtle and Rlent, thanks again for the suggestions. I'll let you know what the outcome is.

 

[Turtle]

Skip the AC gauge, unless you really know what you're doing. I'd be leery of getting into the integrity of that system unless you have the proper tools. Take the fuse into an Autozone or wherever and have them test the fuse. If it's bad you can get the replacement there. Then change the cabin air filter if it hasn't been changed in a while. They can get clogged up real quick and will make a huge different not only in airflow but cooling efficiency. After that, then I'd have a dealer check the freon level.