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

rocketman461 · Post by **rocketman461** » 04 Feb 2024, 16:33

I have had this 98 XC70 for about 7 years with no real problems except for bad front axle bearings, worn struts, the A/C clutch needing to be shimmed, the ABS module needing soldering, etc. It has about 157,000 miles on it.

Last winter, when the outside temperature dropped below 30°F and the car had not been running for 8 hours or so, I found that the climate control would not show the lights for the A/C compressor nor the Recirc light and the fan would not come on. After a while of letting it warm up (15-45 minutes - depending on OA temp), the climate control lights would come on and the fan would start. Towards the Spring, the issue would lessen. It ran the A/C just fine all Summer and started messing up again when it got cold this year.

I tried warming up the control panel with a heat gun (set on low heat) to no avail. I was about to buy a block heater (thinking that it had something to do with coolant temperature) but I figured that I'd try asking here first. My 83-year-old mother drives the car occasionally and now she's afraid to drive it.

Thank you,
Brad

Post by **scot850** » 04 Feb 2024, 23:05

The AC does not run at those low temps. Can't recall what the minimum temperature is. Check your handbook.

https://volvo.custhelp.com/app/manuals/ ... /om_id/952

On page 37, the manual says the AC does not run under 0C/32F to protect the system.

Neil.

Post by **abscate** » 05 Feb 2024, 04:45

The AC needs cabin temperatures above 40F to prevent freeze up, but the lights should come on at all temperatures

26 year old electronics need work over of solder joints. You can also try an exact 1998 part number match from junkyard or eBay

rocketman461 · Post by **rocketman461** » 05 Feb 2024, 08:36

Sorry, I didn't explain my problem correctly. Below 30°F OA temp, nothing works nor do any climate control lights come on (except the background lights). No heat, no defrost, no fan, no nothing. As soon as the car warms up, the lights come on and the heat and/or defrost works and the fan starts. The entire system works fine at any OA temp above 30°F. The funny thing is that it does it every single time the OA temp is low.

I will try checking the internals and, if necessary, replacing it.

Thank you

jmartin919 · Post by **jmartin919** » 05 Feb 2024, 08:41

Sounds like a connection is opening up or internal solder joint. Maybe try reseating the ECC connectors.

Post by **scot850** » 05 Feb 2024, 13:03

Do you leave the ECC unit in Auto mode? If you do, what happens if you try to move it to manual setting on fan speed? If it is still dead then as the guys say, that is a different issue as they have suggested.

When did you last clean the cabin air temp sensor? It is fiddly to remove but is the the left of the ECC unit behind the dash.

Neil.

Post by **BEJinFbk** » 05 Feb 2024, 23:14

abscate wrote: ↑05 Feb 2024, 04:45 26 year old electronics need work over of solder joints.
You can also try an exact 1998 part number match from junkyard or eBay

Agreed - Does sound like it could be
an intermittent solder joint in the ECC.

Or possibly something in the power chain.
Start with checking fuses, wiggling the ignition
switch for possible failing electrical contacts.

Along those lines - Maybe an aging accessory overload relay?
Are any other things not working when the ECC is dead?

And the suggestion of unplugging and reseating the ECC
connectors may pay off, too. Don't cost nuthin'.

rocketman461 · Post by **rocketman461** » 10 Feb 2024, 12:07

Thank you for all your replies and for sharing your knowledge! I will try all of these tips and report back here.

Brad

WillieBeamen · Post by **WillieBeamen** » 02 Mar 2024, 21:34

Bumping this because I'm having the same issue. I drove 30 minutes to work spraying about a gallon of washer fluid on the windshield in 24 degrees the other morning.
I have verified 12v power at the ECC plug during the non working time. I just replaced my ECC from one from a junkyard. Hopefully it's a good one. The other posts I've found with this issue is resolved with a JY ECC. Enclosed is photos of the broken ECC. I'm willing to send out the guts to anyone smarter than me that wishes to look further to help the greater good of the P80 community. It seems likely to have more of these failures in the future. 1998 s70.
The ECC comes on at 3:17 in the video

WillieBeamen · Post by **WillieBeamen** » 11 Mar 2024, 15:41

I'm back to report that my junkyard ECC also doesn't work when it's below 40. I'm glad I have heated seats.

I keep looking for any abnormalities on the actual PCB of the original but I don't see anything with my naked eye or under a magnifier glass. I guess I'm posting because I'm at a loss. If anyone has any idea, I'll try it. I'm willing to have it refurbished at this point.

I'm going to post some threads, to further document this gripe

viewtopic.php?t=94159&hilit=climate+control+no+power