How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Doug C. Your Own Question

Doug C.
Doug C., ASE Certified Technician
Category: Volvo
Satisfied Customers: 5815
Experience:  Volvo Enthusiast and extended work experience from a Volvo specialized shop
Type Your Volvo Question Here...
Doug C. is online now
A new question is answered every 9 seconds

2001 volvo S40: dash lights..the whole climate control module was

Resolved Question:

We just bought a 2001 volvo S40 for our daughter. The a/c comes on and off intermittently but we have no control as the buttons don't work, although if I press the DSA button that light shows up on the dash lights. We thought the whole climate control module was bad so we bought a used, switched it out but having same problem. We may drive for a half hour then all of a sudden the a/c will start blasting and the little ac light will go on. Any advice is appreciated. Thanks!

Sweating in NC
Submitted: 2 years ago.
Category: Volvo
Expert:  Doug C. replied 2 years ago.
Hi,

For clarification, when the problem is occurring, do you have no cold air, or no air flow at all from the vents?

I want to be clear on what you mean when you say the light comes on and off but you have no control as the buttons don't work.

Thanks
Customer: replied 2 years ago.
If i press the a/c button to turn it on, nothing happens, if I press the defrost button nothing happens, if I press the heated seat button nothing happens. If I press the DSA button the icon lights on the dashboard showing its on. So I've pressed all these button and nothing has happened then maybe 20 mins later...or 5 minutes later...or maybe 60 mins later the a/c light will come on and cold air will begin blowing from the vents but if we try to adjust the air flow we can't. Sometimes hot air will blow out instead of cold..no control. When the a/c goes on and the a/c light comes on, all the other buttons will then work but the a/c button will not, meaning we can not turn it off and we can't adjust flow or temp.
Expert:  Doug C. replied 2 years ago.
Thanks.

When the panel is not working, is there air flow coming from the vents?
Customer: replied 2 years ago.
No
Expert:  Doug C. replied 2 years ago.
Thanks.

When the panel is working and you have air flow, have you ever checked the heated seats to see if they work then?
Customer: replied 2 years ago.
yes, they work then
Expert:  Doug C. replied 2 years ago.
Thanks.

Give me just a few moments to double check a few things. While I feel confident about what your primary issue is, I'm a bit confused about the heated seat portion of the equation and want to look into something right quick.
Customer: replied 2 years ago.
ok...i'm not going anywhere.
Expert:  Doug C. replied 2 years ago.
Thanks for your patience.

The big picture issue that you want to be concerned with is if the control head is losing communication with the central electronics module. Unfortunately this is nothing that can be checked on your own, as it requires a Volvo factory scan tool to access the CEM... but realistically this is your primary suspect

As far as going separate routes, I am having a difficult time attributing the heated seat operation failure to the rest of the issues you are having.
The problem here is that the heated seats consist of a fuse, the climate control head, and the heated seat modules/elements in each seat. The only shared component in the entire heated seat system is the control head itself. Having swapped another control head and had the same reaction with the seats as well it is very unlikely that you would come across two units failed in exactly the same way. While these control heads are famous for failure, this particular failure you describe, not so much.

Regarding your AC controls going out; focusing on the air flow issue lets look at it the same way as the seats. You have fuses, the control head, a power relay, a power transistor, and the fan motor.
Fuses are solid state an are either good or bad. The control head has been replaced with a unit that is presumed to not be failed in the same way. We now have the relay, transistor and fan motor as potential failure points. If the motor was bad, it is not typical for it to come back to full operation, and even if it did, you would be able to control the speed, not be stuck at one speed. If the relay were to fail you would *lose high speed, not be stuck on one speed. Which brings us to the power transistor. When this fails you will lose operation entirely, and if you have a brittle connection inside one of the transistors in the pack, you will lock at a random speed and have no control over fan speed.
And guess which problem occurs very frequently...

Now back to the seats issue... there is really no connection that can be made here with one exception; I have seen power transistors fail in such a way that they back feed and cause issues with the temperature adjustment in addition to fan speed, etc. Theoretically it is possible that this could be occurring here with the seats as well since these are all incorporated into the control head.... it is a bit of a longshot though.


Honestly with the situation you describe, and -this is important- assuming the control head is OK since it was replaced, I really feel you are going to have a communication issue dropping out between the CEM and the climate control head. It is the only standalone issue that could cause all of your issues. I would feel most comfortable inspecting the communication between the CEM and the climate head before investing in any other parts.
If you were set on trying anything else before bring the car in to a shop, I would say try the power transistor under the passenger side dash as your AC-only related issues fit that particular failure perfectly... .the heated seats however are the ones that really kill that as a slam dunk in this situation. Otherwise I would be confident on a transistor failure.
Doug C., ASE Certified Technician
Category: Volvo
Satisfied Customers: 5815
Experience: Volvo Enthusiast and extended work experience from a Volvo specialized shop
Doug C. and 4 other Volvo Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • The nearest Volvo dealer is 160 miles away. Best $15 bucks I have spent in a long time! Paul M Corpus Christi, TX
< Last | Next >
  • The nearest Volvo dealer is 160 miles away. Best $15 bucks I have spent in a long time! Paul M Corpus Christi, TX
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
 
 
 

Meet The Experts:

 
 
 
  • Enes's Avatar

    Enes

    VOLVO Technician

    Satisfied Customers:

    4240
    15+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase
< Last | Next >
  • http://ww2.justanswer.com/uploads/enesd/2009-12-27_031829_eneswork.jpg Enes's Avatar

    Enes

    VOLVO Technician

    Satisfied Customers:

    4240
    15+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase
  • http://ww2.justanswer.com/uploads/IN/InTheIROC/2011-8-10_4561_5454.64x64.jpg Andy's Avatar

    Andy

    Volvo Expert Technician

    Satisfied Customers:

    3008
    One of only a handful of ACTUAL Volvo dealership technicians on JA, ASE Master Certified with L1
  • http://ww2.justanswer.com/uploads/VO/volvoexpert1/2012-6-7_32422_Billand54Merc2avitar3.64x64.JPG volvoexpert1's Avatar

    volvoexpert1

    ASE Certified Technician

    Satisfied Customers:

    990
    Volvo Master Technician with 15 years excusively with Volvos. Also ASE L1certified for over 10 years.
  • http://ww2.justanswer.com/uploads/dramey04/2009-08-31_234152__083109_1938a.jpg dramey's Avatar

    dramey

    ASE Certified Technician

    Satisfied Customers:

    663
    have worked on volvo's for 4 years and am a ase master mechanic. current shop foreman
  • http://ww2.justanswer.com/uploads/Barlogio/2009-06-17_004912_Copy_of_Picture_25.jpg Jim B's Avatar

    Jim B

    ASE Certified Technician

    Satisfied Customers:

    496
    40 years Import and domestic AAA Approved Shop owner 30 yrs
  • http://ww2.justanswer.com/uploads/tsmodie/2009-6-10_144056_tim.jpg Tim Mohr's Avatar

    Tim Mohr

    ASE MASTER TECH

    Satisfied Customers:

    437
    30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
  • http://ww2.justanswer.com/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Engineer

    Satisfied Customers:

    259
    Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing