no high speed on blower

[batmo]

Ive got an '86 that wont blow on high. low and medium works fine.

have replaced the switch allready.

any suggestions? thnx!

[Rileysowner]

If it is not the switch it could be the blower resistor module. I'm not sure where it would be on your model year, but I'm sure someone will be able to say, or you can just follow the wires back from the blower motor.

[CaptSquid]

Some years had a high-speed relay, available, unfortunately, only at the stealership. The aftermarket relays may work, but don't fit. Yours is in that group.

[6spd_monte]

I had the same problem on my '87. The blower relay fixed it. It is located on the passenger side of the firewall, near the blower motor, right next to the fuel pump relay. The blower resistor is also located nearby, it is in the evaporator case.

[batmo]

I bet it is the blower relay! I wasnt aware it had one.

I'll report back what I find.

thnx again!

[batmo]

Yes it was.. but it wasnt actually a bad relay. It had a bad ground connection at the relay.

the plastic arround the ground connector was actually melted too. I cleaned the connections and lubbed them with dilectric grease and re-installed. now its High-Speed again!

thnx

[6spd_monte]

Cool! It's always nice when it costs zero dollars to fix the problem!

[crash]

resurrect ....

anyone tell me where this high speed relay would be located on a 97 ?

thanks
rob

[astroturf]

Crash,

There is a good PDF explaining where, and how to replace.

It can be found here: http://www.benoitcloutier.com/BAGNOLES/ ... tor_EN.pdf

Hope it helps, Jim

[crash]

thanks Jim.. actually, knew all that one.. that's if the high only is working and none of the others.

mine is the opposite, like the first post.

I think you might be confusing the blower motor resistor with the high speed relay

[astroturf]

Oops Sorry

[astroturf]

Crash,

I did some diggin, and the High Speed Blower Relay is inside the resistor assy.

Hope it helps, Jim

[crash]

hmm.. interesting. thanks for checking into that Jim.. (and redeeming yourself hehee)

[hbastro1994]

BLOWER RESISTOR HAS NOTHING TO DO WITH HIGH SPEED FAN OPERATION!
If you look at a schematic you will notice that when you have the fan speed set to "high, " 12 volts is supplied to the high "a/c blower relay", which (after the contacts close) sends 12 volts directly to the blower causing the fan to run at high speed. At the same time this relay is activated, the "blower resistor network" is removed from the fans circuit by way of the "blower switch." So it is impossible for "blower resistor network"to have any influence upon the fan and it's operation! This applied 12 volts supplied through the relay to the fan comes from a "junction block" which is always "hot" with 12 volts. It runs through this junction block, then through a "fusible link fuse," then to the contacts of the a/c blower relay.

[hbastro1994]

NO CHASSIS/BATTERY GROUND ON BLOWER MOTOR?
I have a 1994 Astro van with no high speed fan operation, all other speeds work. I've noticed that the ground lug (and blower case) are not electrically connected to chassis ground (battery ground). The blower motor's case appears to be isolated from the chassis . Hmmm? How can the fan operate on all other speeds but not the high speed, especially if the blower ground is isolated from the chassis (battery ground)? On high speed, there is voltage on the relay side, and the relay is activated. I shorted this red wire to the purple wire (which attaches to the blower) so as to eliminate the relay, but, nothing happens! It seems that there is not enough current to run the fan on high mode. Something weird in this supposedly constant hot (12v) side of the relay. While I had engine set to 'run' and climate control fan set to 'high' I tried to get the fan to run in 'high' by also connecting a ground from the chassis to the ground side of blower. STILL, THE BLOWER WOULD NOT RUN AT ALL! So if its a ground issue why wouldn't the blower work when I applied this ground? Interestingly, if I unplug the ground from the blower and check for continuity of it to the chassis (battery ground) it is shorted/connected. So to recap, I only have chassis/battery ground connected through ground wire which attaches to the blower, but, no ground from blower case to chassis/battery ground. What am I not seeing?

Also, does the cpu/pcu supply a 'bias voltage "to the 'always hot side of the relay?" If it did, this could account for no high current to operate the fan on high speed. But, I eliminated this possibility by using my test lamp at this red wire on relay to ground and it did not light.

UPDATE: HIGH SPEED FAN CAPABILITY CONFIRMED.
I was able to confirm blower motor does work at High speed by connecting the positive side of the battery directly to the fan. I disconnected the purple wire from the high side of the fan and left the black ground wire plugged into the fan. SO, THIS PROVES THAT THE 12V ON THE RELAY SIDE IS NOT ABLE TO SUPPLY THE CURRENT NECESSARY FOR THE FAN TO OPERATE THROUGH THE RELAY. THE ISSUE NOW IS TRYING TO FIGURE OUT WHERE THIS RED WIRE GOES. THE SCHEMATIC SHOWS THERE IS A FUSELINK IN SERIES GOING BACK TO A "POWER DISTRIBUTION, JUNCTION BLOCK. NO IDEA WERE THIS IS LOCATED OR WHAT TO DO ONCE I FIND IT.

Note:
BLOWER RESISTOR HAS NOTHING TO DO WITH HIGH SPEED FAN OPERATION!
If you look at a schematic you will notice that when you have the fan speed set to "high, " 12 volts is supplied to the high "a/c blower relay", which (after the contacts close) sends 12 volts directly to the blower causing the fan to run at high speed. At the same time this relay is activated, the "blower resistor network" is removed from the fans circuit by way of the "blower switch." So it is impossible for "blower resistor network"to have any influence upon the fan and it's operation! This applied 12 volts supplied through the relay to the fan comes from a "junction block" which is always "hot" with 12 volts. It runs through this junction block, then through a "fusible link fuse," then to the contacts of the a/c blower relay.