Fan stopped working on high setting..

Boss came home & said the fan quit but what air was coming out seemed to be blowing cold..

Had a quick look & the fan worked on the first 3 settings but not on high.

Hmmmm..:shakehead

Lucky for me ..nothing serious, otherwise ..boss gets like this ->:runaround:
:lol2:

YEA SOUNDS LIKE BLOWER RESISTOR.lots of info here if you do a search

Resistor not used with high speed. Check high speed relay and socket, a common problem specially with those using the high speed setting for long periods. On high, this is 25 amps pulled through wires and relay contacts...a little more than the design value of those components, it seems.
www.avigex.ca/xport/heaterrelay.jpg
www.avigex.ca/xport/hvac_diagram_front.jpg

depending on the year- it couild be the circuit breaker as well- swap it with the one for the power seat-be careful they can get really hot- if car has been driven lately- on left side of dash is the breaker box...

Only had a chance to do a quick google ..so far. Found this (http://www.gm-trucks.com/forums/index.php?showtopic=68557) thread interesting (quotes below) as it talks about a worn out blower motor ..blowing resistors.

Probably mine is original & was gonna get around to changing it, the main problem being in winter when at low setting, where normally you don't even know (or barely hear) the motor is running, instead there is a constant audible chirping (for lack of a better word) sound that goes away at higher setting..

Read about a fix (years ago..) involving drilling a small hole at the back of the motor & getting some grease in the bushings (bearings?).

Read a thread here where there are 2 types of blowers & that one is not right (or doesn't work ..fit) ..or something.
If the resistor is blown, there is probably a good reason. You should also check the blower itself so you dont end up changing the resistor again in a few days/weeks when it blows out again because the blower motor is starting to go bad. My 93 had some noise in the blower bearings for a while when "I didnt have time" to change it.. finally my resistors burned out for the lower settings and I ended up changing everything and everything worked great then. My dad went through 3 sets of resistors before finally changing the blower motor like I told him to do the first time http://www.gm-trucks.com/forums/style_emoticons/default/lol.gif Mike is right and wrong. A bad blower will take out a resistor but resistor replacement especially the original on a 2000 is common. Gm used to use a card (very thin) with resitances built in to control blower speed they overheated easily and died. In the last couple of years we have gone to a much beefier type of resistor that dissapates heat much better. Go GM only on the replacement and if your resistor goes bad in xx time not sure how long probably a year you get a new one for free then buy the motor.I have manual seats so can't swap that circuit breaker.

BTW brcidd ..also have a 88 gm 3500 rat powered dually ..~245 clicks total now but with a fresh motor at ~ 217 thou..

..in case you did not notice: (see links in post above)
- there are no breaker nor fuses in the high speed circuit: just fusible link H that, if blown out, would kill a lot of other things too and alternator would not charge
- there is no resistor in the path of the high speed circuit: just the high speed relay.

..in case you did not notice: (see links in post above)
Hmmm ..missed the point of your post (half asleep ..work nights..) when I had a look at the thread yesterday. Looks like it's right on the money.:smile:

Turns out there's a Partsource (http://www.partsource.ca/) store around the block from where I live that I just started to check out. My understanding is they're part of Canadian Tire & I like what I see so far. They have the relay in stock for ~ 40 bucks, fan motor for ~ 60 & with the fan ~ 100.

Ended up grabbing a set of cheap front pads for ~ 20 bucks (good ones were ~80). Had them replaced last year but..wrench said they wear out quick compared to the backs. He said he put in fresh shoes in the back a few years ago for certification with purchase & when I asked him to have a look .. said they last forever..:shakehead but I'll have a look at those too.

Haven't done much of my own maintenance in years.. but getting back into it again now. 2 of my kids just got their liscences just recently (learned to drive in the Tsport) & want the vehicles in tip top shape. I've had ~ 4 partial brake failures ..over the years, 3 were brake lines & the last one ..a rear wheel cyl let loose ...pedal went almost to the floor but the fronts still worked. When the shoes were replaced ..wheel cyl was bone dry.. Had one (wheel cyl) with a slow leak ..in the past, but never one that just suddenly blew..

Have a few dodge minivans & doing some extensive brake work on those right now including rolling my own brake lines.

Bingo! The #80 & 37 pins were visibly burnt (& plastic melted) at their bases, where they meet (& go thru) the plastic of the relay casing.

Boss likes 'er air..:grinyes: full blast..

Resistor not used with high speed. Check high speed relay and socket, a common problem specially with those using the high speed setting for long periods. On high, this is 25 amps pulled through wires and relay contacts...a little more than the design value of those components, it seems.
www.avigex.ca/xport/heaterrelay.jpg (http://www.avigex.ca/xport/heaterrelay.jpg)
www.avigex.ca/xport/hvac_diagram_front.jpg (http://www.avigex.ca/xport/hvac_diagram_front.jpg)Last qvestion.. Is the fan a press or bolt on to the blower motor? With a bolt on, they sell the blower motor seperate & cheaper, & you can use the old fan ..so i'm told. I'll have a look at the old one first..might be some evident reason for the chirping noise at the low speed setting in winter (leaves, debris, dirt etc..).

Bingo! The #80 & 37 pins were visibly burnt ..Boss likes 'er air..:grinyes: full blast...
..probably 30 and 87....great anyway if you fixed it....
both fans versions..that is bolt on and press on..were used and if you get a complete motor and fan unit from salvage, one or the other will be OK
however, beside the chirping noise, "full blast" for long periods is sufficient as the explanation for the situation you found.

..probably 30 and 87.... :meant:

Ok, got around to pulling the blower motor & didn't see a bolt on the fan so assumed mine is a press on; was dated 96 so assume original.

Had a ~ tuff time pulling it out, finally figured out 2 bolts for the coil pack then moving it aside & had to unclip & move aside a wire loom. Still didn't come out easy & ended up snagging & pulling hard to force it out. The plastic fan isn't very strong & is sharp enuff on the edge of the blades that it is easy to get small cuts on the fingers ..if not careful.

Decided to try & lube it to see if the chirping squeaking noise'd go away & reinstalled it. Seemed to help but then on high setting, turned into a loud vibrator:screwy: that could be felt (big time) in the car & heard from a distance. Dunno what that was about but prob had to do with forcing the thing out & maybe damaging the fan though I couldn't see anything evident when I pulled it out again; lot easier this time. Was a bit worried that I may have bent up the mounting hole & would have that vibration noise/prob with the new unit

Anyway, ordered a new unit with a press on fan but it came with a bolt on setup;:runaround:went in without a hitch ..& boss is happy ..likes 'er air cold & heat ..full hot..:iceslolan

I have the same problem on 00 Gran Prix. No speed 5. My additional problem is speeds 1-4 appear to work but stopped blowing out any vents. This has happened twice when I traveled into a colder area. Is it possible there is a damper freezing shut that shuts off the air flow in addition to the problem of not having any high speed on the blower? We replaced the blower motor last year and then had a problem with air flow. Speed 5 never did work after the blower replacement.

If fan works on lower speeds, then the fan is OK also for high speed: fan has one winding only. High speed is controlled by a separate relay in former year models...but in 00, GP or TS(montana), the HS relay is imbedded with the resistor block.... check http://www.avigex.ca/xport/resistorblock2000.jpg

Looks like the high speed relay broke after ~ 4 mths.:mad: Pulled it off & pins looked normal compared to the original's that were burnt.

Thought the relay was only for high speed but after I pulled it, fan switch didn't work at all; prolly just get another one.

Had a closer look at the ~ new relay in better light & there was definitely slight (brownish, burnt) overheating discoloring of the #30 pin that stood out from the rest, though the base wasn't melted & overall wasn't nearly as bad as the original that failed.

Folks replaced it under warranty & we figured the old fan blower motor (now replaced) may have caused the early failure of the first replacement relay.

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.

...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...

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

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.

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.

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.

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

....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....
http://www.avigex.ca/xport/hsrelaywiring.jpg
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.

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.