I'm a first time forum user and stayed up half the night looking forsolutions to gremlinssimilar to mine! This site is great-you've saved many people alot ofmoney and time.
The ACC panel recentlystarted blinkingwith codes 4-1-7 and 4-1-8 pulled from the diagnostic unit. Also, the blower fan unit will only runon a lowfan speed when the slide bar is pushed toits highest manual setting or on AUT.You can eventually get the fan to highspeed by switching the key switch several times, but it always defaults to the low speed.Any ideas are greatly appreciated!!

 

Welcome to the forum, I hope you find it helpful.

As to the codes.....
417: Pax side temp sensor intake fan seized.
418: No control signal to ECC power stage.

Usually it is the power stage (resistor) that fails. On a rare occasion, the control unit itself seems to fail but in this case it seems like the resistor is shot. Moderator Tech would be able to pinpoint it better than I could.

In case if the resistor is found faulty:
http://www.fcpgroton.com/volvo850cooling.htm
http://www.eeuroparts.com/searchresu...5&cat=1000

FCP Groton has it for $109.

Wait to hear other opinions before you decide to spend $109 + shipping.

I hope this helps.


JPN

 

Thanks JPN, I tried another control unit this afternoonand gotthe same results as the original with the HVAC blower motor still not running on high. As you suggest itappears to bethe resistor.Thanks for the advice!

 

My pleasure, I hope the problem gets resolved soon. Please keep us posted, luckily there are many members in the 850 forum who are extremely knowledgeable, with Moderator Tech being the top.

Have a nice Turkey Holiday, send some dark meat over to Japan if you could.


JPN

 

Dear JPN, I went to ye 'ol local salvage yard today which resulted in the following-- All the 850 ACC's were stripped out (imagine that!). Itook a blower off a '95 manual CC, and it looks new and works fine ($35), but performs just like my original. No useful blower resistor because it was the manual HVAC unit. I tookthe onlyblower resistor that looked like my originalI could find off an S70 and tried--both blowers kick on high for a second (at least they run on high), then shut off completely.This seems to confirm yourbad resistortheory when I can get a proper replacementresistor--do you agree?I'm getting pretty speedy at removing blowers/resistors now, and I'm headed to a different yard tomorrow.I'd gladly send you all theturkey you can stand-I'm sick of it!! Thanks for all your help.....Tennessee850

 

I don't know much about the ACC system as my 850 has the MCC in it, but I know blower high on mine actually bypasses the resistor and has its own fuse (40A IIRC). Might just want to check that since it's free to check.


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Thanks for the feedback. Thisproblem has another weird symptom. If I switch the key off and on many times, the high speed will eventually work and the system will continue to work properly (using the manual variable speed slide bar) until the key is turned off, and then default back to not working on any speed but low. With enough patience I can eventually get it back to the high speed. I waswondering if the control logic for thehigher speedsis in the resistor itself ? Thank you for yourresponse!

 

It wouldn't surprise me. Looking at the two different ones the one for ACC looks much more complex, larger heat sink and casing so I would think it is safe to assume that there is some control that is on the resistor pack itself.
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Thanks info2x. Well, I made another run to the areas salvage yards to no avail on the resistor. It seems it is going to be very difficult to find the correct used resistor forour 'ol "chiseled brick" (we love that name). Also, the parts guys are askingfor the VIN, and that two types areavailable depending on the VIN. Think I'll go the FCP Groton route and see what happens.We can't afford to be stuckwithout high speeds on the blower. I'll let you know if thisfixes the ills. I've got plenty moreproblemsto tackle once I get the blower fixed sincemy old brick is a turbo that has lost alot of power of late. Thanks again!

 

They are asking for a VIN to determine your chassis number (last few digits IIRC) because that was the split between the apparently two different types of resistors for the ACC system.
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Makes sense on the VIN. Hopefully I'll cure the fan speed issue with the resistor and thenwork to clearthe 417 code. I'm also getting a consistent 231 on the engine management diagnostic (A2) after clearing several times. I've had the car for over 50K and have not changed the O2 sensors. FCP Groton seems to be the most reasonable for sensors at $95 each. Any other options that are better?If not, I'll get them when I order the resistor. The local parts guys want $90 for a Bosch that I'll have to wire toan original connector.Thanks for the advice--

 

I installed the new blower motor resistor ($109+shipping)and this solved all my problems. The 4-1-7 and 4-1-8 ACC codes no longer flash and the unit works great again. The wife is happy..life is good for now!Except for the 'ol oil dripping, exhaust smoking (after long idle periods, and the smoke is whitish withan odd odor), 2-3-2 engine code producing turbo? The turbo needle stays way to the left and only barely breaks center upon hard acceleration. The local Vovlo shop says it is time for a turbo replacement. The car has over 160K miles, but still runs great, but is definitely down on acceleration. I've checked all the vacuum lines and cannot detect a leak. What does the turbo gage laying over to the left indicate? Thanks for all the help on the heater fix.