Fan stopped working on high setting..

[96tsport]

Looks like the new relay blew.. Any thoughts before I try to take it back (2nd time now) & dude sez.. something else is causing the high speed relay(s) to blow.

Blower motor is fresh.

[LMP]

...beside an actual "something else".....mm...I do not how you used the blower, but the relay contacts and socket can't endure high speed for long periods of time, as motor pulls at least 25 A on high setting....this is a heavy load by any means....and this whole circuit is unable to cope with that except for short high speed bursts : I know mine starts smelling burnt wire after a few minutes...and I noticed that early when I had car, and never use HS for more than 1 or 2 minutes. ; the same is true with my other car, a Kia SPortage. There have been several..well, many cases of relay failures on this very forum specially when high speed setting is coupled with high temperatures using A/C....the motor has some cooling (external rubber hose) , but not the relay. OF course you could take an amp reading to the motor on the high setting, but 25A is the expected amp for the motor , but proven excessive for the relay....
CHeck in case some amp rating is stamped on the relay or relay box: there might be different grades, specially if after market.......a lower rated relay will surely consume itself; a high rated relay with larger contacts will generate less heat losses...

[Jeffrv]

First relay went on mine when van was about 3 years old, second one ( and wiring harness) cooked 2 years later. Replaced it with a 30A Bosch style relay, and have never had any more problems, even use high settings for extended periods. I think this relay has large spade style connectors, not the needle thin ones of OE, and was cheaper too. However, it does involve cutting off the old connector and installing a new one to fit the new relay.
Jeff

[96tsport]

Bit of a strange situation.. wife reported that all fan setting stopped working & when I first checked it pretty sure that was the case & pointed to a blown fuse.

Ended up pulling it (bottom right area of the fusebox) & the one below (above ..forget). Both fuses were fine & when I put them back, setting 1-2-3- worked but no high speed.

With the original relay never paid much attention to how long run on high setting, but lots in the hot summer and or cold winter & didn't start acting up 'till this year (later part of 08).

Though, 2 relays have acted up ~ quick since then, one was when still using the original blower motor but was starting to wonder if the relays came in diff ratings with the second replacement acting up real quick & looks like they do.

So, still could be the first replacement relay blew early due to use with the old original blower motor & the second one just acted up, though this time with the fresh blower, but could be a wiring scenario also.. at this point. Wouldn't surprise me that there are cheezy relays out there..& better ones but looks like the Bosch is a sound upgrade all round.

Thx for the input, i'll report developments.. Nothing like input form folks who have the exact same setup.

[LMP]

Originally Posted by 96tsport

Bit of a strange situation.. wife reported that all fan setting stopped working .

INdeed ALL speed settings pass through the high speed relay:
www.avigex.ca/xport/hvac_diagram_front.jpg ; current for the lower settings pass through the "normally closed" contact (87A to 30 : contacts that are made when the relay is in "released" state...; while high speed is through contacts 87 to 30; pull the high speed relay out...and none of the speeds will work....so a damaged relay or socket can indeed impair all speeds.

[96tsport]

It it's only the relay that's acting up at this point & everything else is ok, (haven't had a close look..) this would be the first time I have a complete relay failure. I'd say that's possible but looks like the 1-2-3 setting is (was) an intermittent problem, cos it works now. That's also assuming nothing else is contributing to the problem.

I doubt that pulling 2 good fuses & putting them back in had anything to do with setting 1-2-3 starting to work, but that's what happened.

I think I had the engine running & who knows, heat, wires etc..

Mentioned pulling the relay in a prior post & finding out the switch didn't work at all without it. Didn't make the connection the relay could be plugged in, but with a complete failure cos if it is only the relay.. its the first time it failed that way, even if only intermittently.. at this point.

[96tsport]

Don' t imagine I could just bypass the relay at the high speed circuit wire & use a 20A fuse?

[LMP]

Originally Posted by 96tsport

....I could just bypass the relay at the high speed circuit wire & use a 20A fuse?

..well...yes...replacing the relay contact from 87A to 30 with a straight piece of wire (or a fuse) would give the lower 3 speeds....

but do not try to have the High Speed 30Amps pass through the control switch and control wiring....(85 to 30)..this would ruin the switch and control wiring...an probably would be a fire hazard.

A safe option ..other than going for a new relay and full health socket...would be running a new separate heavy gauge wire (AWG 12 ) with a separate heavy duty switch from 87 to 30....this would be for adding the high speed setting only. But I think this is more of a nuisance than going for the authentic setup....but sometimes, nuisances save the day...or at least allow for a "proof of concept" test.

[96tsport]

Looking into this further.. noticed the original relay has 85 86 87 87a 30 with 5 wires..

Got a relay with 85 86 87 30 & only 3 wires output, red (2 are combined but one output) white & orange, doesn't seem to be a black ground..

Anyway to hook it up to the original wiring? Maybe just the high speed circuit & bypassing the original relay? It's rated 30 amps.