98 S70 - Climate Control - Strange Behaviour

aj98s70 · Post by **aj98s70** » 16 May 2007, 10:07

I have a 98 s70 GLT with 94k Miles.

Lately the climate control system has been acting really strange. I set it to 70 and AUT - First thing in the morning when the outside temperature is about 50, it does not blow any hot air when set on AUT. Later in the day when the outside temp is about 75 (and the cabin is warm due to being in the sun all day) AUT seems to work okay - the blower works, although the air coming out is not very cold. Yesterday the temperature was in the mid-80s and the system completely failed. I got flashing lights - no air through the vents in AUT or any other fan setting.

I am not sure where to start troubleshooting. Any advice appreciated.

Thanks in advance....

Post by **pfeener** » 16 May 2007, 12:17

The flashing lights when you first start the car indicates a failure code. You can bring it to the dealer and they can read the codes. An OBDII reader will not read these codes.

My advise is to limp along in manual mode if you can. The climate control in the 850's and S70's was awful. I had mine fixed several times while it was under warranty and a few times after that and it still doesn't work correctly.

Post by **Maxbaby** » 17 May 2007, 13:30

My two cents would be the following...

Locate the temp sensor behind the entry assist handle above your head on the driver and passenger side. Pry out the plastic cover and just make sure the sensors and the little hole in the covers are clean and not clogged up with dirt and dust. A little compressed air... be gentle.

Pull the ECC unit from the dash and run some compressed air through it, again to blow out any dust. If you are adventurous, you could locate a used ECC, often available on Ebay for relatively cheap prices ($20 to $75 depending on who's selling), and try plugging it in to see if that cures your problems.

From what you are describing, it doesn't sound like you're having a problem with the damper doors or damper motors (the flaps that open and close inside your HVAC system) but the best way to know that is to get the codes read, in which case you can post them and someone can point you in a better direction. Could be a cabin sensor, could be a problem with your A/C system, could be a few things... the codes will help.

Sometimes a gremlin will have visited you and if you're lucky, by running the codes and resetting them, everything will be zen again.

aj98s70 · Post by **aj98s70** » 18 May 2007, 10:57

Thanks for the advice Maxbaby and pfeener.
I am going to have to get the codes read.

I did clean out the temp sensor - I thought on the 98 vintage the sensor is next to the TRACS and Sunroof Switches. I used a vaccuum cleaner and that got most of the lint-like dust.

As far as getting the ECC out of the dash - do I just pry it out ?

Post by **Maxbaby** » 18 May 2007, 12:51

I'll defer to someone else here for clarification, but I am under the belief that your 98 will be like the previous 850 dash... release your stereo and pull it out, then reach under and up to the bottom of your ECC. You should find a release button that allows you to pull the ECC out of the dash and then just disconnect the wiring harness from the back.

... try doing a search around here for the specific removal instructions for your 1998... if the temp sensor isn't in the same place as mine, then I'm not sure if your dash is the same as mine??(... sorry 'bout that..)

--> Actually, I did a little search to answer my own question above... didn't get that far... have to get to work right now... however, have a good read over the following link, a previous post talking about a lot of issues. It may not refer specifically to your situation, but will help edumacate ya, and maybe spurr you on to getting those codes read...

https://www.matthewsvolvosite.com/chat/p ... sc&start=0

Post by **Maxbaby** » 18 May 2007, 14:28

Here's another post... ignore the extra detail and have a look at the "removing the radio" part... this should be your car, and therefore should be that simple...

https://www.matthewsvolvosite.com/volvo_ ... cement.php

... and keep in mind it's just a guess to blow dust out... I am more curious about the codes, and what will happen when you have them reset. I think you'll have more luck that way...