850 heater fan quit again

swe280Z · Post by **swe280Z** » 14 Aug 2018, 18:14

See my posts from last Feb for backround. Replaced fan relay a few days ago because no high speed o the blower. Finished a/c shim wire tie fix and was testing it out for about 20 minutes only to find out that the fan had quit on all speeds! I'm getting pretty good at getting to and replacing the relay but there most be a more permanent repair. I'm getting more familiar with the knee panels than I want. As you can tell from my earlier posts, I've replaced a lot of the related hardware and done a lot of the electrical troubleshooting. Any suggestions would be appreciated. Thanks in advance.

Post by **hausmeister** » 22 Aug 2018, 02:12

Are you sure the fan is ok? Maybe it is worn out and that causes the issues... You can get replacement motors from bosch.
Not sure which relay you mean. There is a resistor and I think transistor control for the automatic ac (?). If your fan takes too much power to spin maybe that burns them out.

swe280Z · Post by **swe280Z** » 22 Aug 2018, 15:25

I apologize for the awkwardly-worded rant which I should have checked before submitting. As it turned out, fan speeds 1,2, & 3 started working the next day leaving 4 the only dead one. I ordered 2 (1 spare) relays for the manual control but haven't installed them yet. Any ideas on what could be wiping out the heater fan relay since the blower and resistor are new? If you read my post from the spring of last year, the one terminal was toasted on the relay at that point but worked for months after the relay was replaced. Is that a clue to the problem? The relays are relatively inexpensive but a bit of a pain to replace. Thanks again.

swe280Z · Post by **swe280Z** » 03 Sep 2018, 17:58

Just finished replacing the heater fan relay again and have all 4 speeds once again. The relay I removed had a bubble on the side (nearest the engine). This is the same terminal that was toasted last year. Still would like a permanent fix. Any ideas? Thanks. Scott

Post by **abscate** » 03 Sep 2018, 19:08

Can you post up a pic of the relay and burned terminals?

swe280Z · Post by **swe280Z** » 12 Sep 2018, 14:43

Replaced the relay again over the weekend. It lasted less than 24 hours. It lost highest speed again.

dj_v70 · Post by **dj_v70** » 12 Sep 2018, 19:25

what is failure mechanism of relay, is the coil burning out or is there an issue with contacts?

Post by **BEJinFbk** » 13 Sep 2018, 08:15

If the contacts in the connector are bad,
there will be insufficient current flow and
overheating will result.
Have you replaced the connector or are
you just throwing relays at this problem?

swe280Z · Post by **swe280Z** » 15 Sep 2018, 19:44

Today I tried to remove the burnt female contact from the connector with no luck. The green plastic was crumbling and the contact getting bent. I forced the newest relay back on and got high fan speed again. Then I tried the next oldest relay but still no high fan speed. Now the working relay is securely taped to the connector for the time being. Does anyone have this connector on a parts car that I could splice in? I'd like to get this fixed once and for all. Now that I was able to remove the connector from its mount and see the burned female contact, at least I have a plan! Thanks in advance.