1993 850 Help! Electronic Climate Control

kludge · Post by **kludge** » 09 Dec 2017, 10:32

1993 Volvo 850 with ECC. 20-valve non-turbo, AT.

Problems started with a squeaky blower fan motor. Ignored it. Then fan not working. Then flashing lights on the AC-off/Recircutale buttons indicating stalled fan motor. No problem, set the system to off and go find parts.

Problem: after getting new parts, still no fan! The lights don't flash anymore (they stopped flashing a while ago, before replacing parts).

1. All fuses under the hood checked and all are good.
2. I got a new fan from the junkyard and it tests good on the bench.
3. I replaced the fan, still nothing. OK check the ECC control module (like a fan resistor but electronic).
4. No apparent problems - MOSFET measured OK, but I replaced all the transistors anyway (I'm an EE). Still nothing.
5. Bought a new (used) ECC control module from EBAY wrecked car. Still nothing.
6. Disconnected and reconnected the battery, just to be sure.
7. There are no junk cars in Indy with the ECC to just try swapping more parts. They all have normal heat/AC with blower motor resistors.

Here's the strange part. There are no flashing lights on the Heat/AC controls anymore. Also, here's the strangest part - checking under the hood for diagnostic codes, port B1 for the electronic climate control, gives nothing. And by nothing I mean when I connect to the B1 port I get a solid LED that stays on forever. Normally to read the codes you connect to the port and press the button for 1 second and the codes start flashing. The LED for port B1 is always on and pressing the button does nothing. If I connect to other ports it behaves normally and I can read the codes.

I'm now stumped and my son needs heat.

TIA.

Post by **rspi** » 09 Dec 2017, 10:39

I'd check a few of the relays. There are two behind the glove box and one J relay at the fuse box.

Post by **jreed** » 10 Dec 2017, 06:09

Interesting problem. I agree with Robert on checking the relays.
You've probably already checked these things:
-- re-install the old original ECC... can you get a read out from B1?
-- check the wiring and connectors to make sure they're not damaged. Are you getting voltage to the fan pins?

Post by **RickHaleParker** » 10 Dec 2017, 06:36

Your an EE ... schematics are on the last pages of the PDF files linked below.

Manual Climate Control: https://www.volvoclub.org.uk/tech/servi ... Manual.pdf

Automatic Climate Control: https://www.volvoclub.org.uk/tech/servi ... m-Auto.pdf

kludge · Post by **kludge** » 11 Dec 2017, 19:27

jreed, yes, no readout before or after the swap - same steady on LED. No apparent connector/wiring damage. No voltage on the fan pins.

Rick, thanks for the wiring diagram. That will help further troubleshooting.

Post by **RickHaleParker** » 11 Dec 2017, 19:58

That will help further troubleshooting.

Using the self diagnostics section will enable to find out what it's complaint is.

kludge · Post by **kludge** » 14 Dec 2017, 18:25

The Self Diagnostics is NOT working. When I connect to port B1 I get a solid LED and nothing else. All the other ports work and flash diagnostic codes.

Post by **RickHaleParker** » 14 Dec 2017, 18:49

The Self Diagnostics is NOT working. When I connect to port B1 I get a solid LED and nothing else. All the other ports work and flash diagnostic codes.

That is a clue, you should at least get 1-1-1. If your not getting anything on port B1, the ECC is brain dead or you got a wiring defect between the ECC and the diagnostic port. Where you able to pull any codes out of the old ECC? Did you check to see if both ECCs are the same revision?

There is a procedure to read ECC DCTs from the front panel of the ECC but, I cannot find it at this time.

kludge · Post by **kludge** » 16 Dec 2017, 10:11

I get codes for every port except B1. Early on I got the flashing on the dash board LEDs when the motor first locked up, but those stopped. Before the fan went out I didn't try to get any codes from under the hood. It took me a month or so from the time the fan went bad until I was able to get to the junkyard and look for a new fan and fan control module, and it's been about a month since that now.

Post by **RickHaleParker** » 16 Dec 2017, 15:11

You do have a ECC (Electronic Climate Control) not a MCC (Manual Climate Control), Correct?
You could get both in 1993. There are 10 revisions, of the ECC. To go from older revisions to newer revisions you had to change some wiring harnesses.

What year and model did you get the "new" parts from? We maybe looking at a incompatibility issue.
Pull the Volvo part numbers off both units and post them. We might be able be able to sort this out.