'98 XC70 Climate Control Has No Power When It's Cold Outside

[BEJinFbk]

If you have two ECC brains that are inop, it may be something else.
I wonder if you have a power distribution problem caused by low temps.
Maybe a sketchy fuse connection, failing relay or perhaps a bad connector
somewhere between the fuse block and the ECC?

What do voltage levels look like on the ECC power pins?
And don’t neglect the grounds on those connectors.

If they all look good, any chance you can get ahold of a
known good ECC for troubleshooting?

[WillieBeamen]

I do indeed now have 2 inop ECC's. Funny thing is the first one wouldn't work below 45 the second one at least works until under 35. It was 40 this morning and it came on fine.
I am also thinking it might be something else, and am going to look at the associated wiring and schematic. But It looks like its going to be the last of the cold mornings until next Monday.

It happened yesterday at 32* but this time I was prepared and had the radio out and the ECC partially pulled out. I first disconnected and reconnected the ECC (while the car was running) with no change. I then opened the under hood fuse box and pulled and replaced fuse C5 (Climate control/ data link) C35 (Panel lighting) and C31 (Climate control) with no change. I then pulled open the Kidney shaped fuse box and rapped on the AC relay (2/22).

With no luck I ran out of time before I had to go to work and just sucked it up and threw it together. It came on roughly 7.5 minutes into my 25 minute ride and worked fine after it came on.

according to the service manual the ECC is grounded under the dash passenger side I'm going to OHM my ground over the weekend and post what I can find.

If anyone has a good known ECC I can buy off someone I'm not opposed. lol

[scot850]

Have you checked the cabin temperature sensor is working? Most forget about these and the clog up with airborne crap over the years which covers the thermocouple bead and jams the small fan motor behind this which draws air across the bead. They do fail (I had one fail) but usually just need careful cleaning with rubbing alcohol and small cotton buds or even a small artists brush. Once clean, spray a little silicon oil on the fan end bearings and then you can check it works using a 9V battery and a couple of pieces of wire. Tape the wires onto each of the terminals and then touch the leads to the fan motor. It should spin. Let it run a little to get the oil into the bearings.

Then re-install.

This thread may help. I added info on the fan removal as it is a little tricky. Make sure you don't drop the rubber cover down behind the center console. It often sticks to the back of the little grille in the center of the dash where it draws air through.

viewtopic.php?f=1&t=70611&hilit=Cabin+t ... ure+sensor

Neil.

[WillieBeamen]

Thanks for the feedback Neil and sorry to not update this thread. boss has me working OT out the butt.

I got another junkyard climate control box. (2nd one) So far it's been working down to 43*F. It looks like freezing temperatures are finished here in North East Tennessee for the year unfortunately (fortunately ) so I will be unable to troubleshoot this discrepancy further until next year. Hopefully I have a good unit this time. I'm almost certain the problem lies in the ECC at this point, and now have 2 inop ECC units and the offer still stands to someone more knowledgeable with semiconductors that would like to try and find the issue.
So I guess anyone that searches this in the future, (and OP) the only option we have at this time is to replace the ECC with a junkyard unit.

[scot850]

Well hopefully it is good now, but like you said, it is hard to test when the conditions aren't there. I guess we wait until next winter with baited breath!

Neil.

[abscate]

TexasT5 very BP nicely followed up his problem that he needed multiple JY ECC controllers before he found one that worked

to believe it has been 3 years since I posted on this.

Car went in and out of driving rotation and fixed a bunch of other things on it. Never found an electrical issue and ECC deteriorated to barely working, except would come on at temperatures above 95 deg and work for 20 min.

Long story short: Yesterday I found a junkyard ECC and bought it. Works great. So my conclusion is my original ECC went bad, first junkyard ECC was bad, and junkyard roulette smiled on me and I got a good one.

San Antonio wrench a part has a 98 red S70 with manual trans and a decent black interior (sans ECC). If anyone interested.

Didn't want this to be another thread with no solution.

TT