Blower fan - A/C

[bouncytruck]

The high speed on my heater/AC doesn't work - the fan shuts off when I flip it to high. I have changed the high speed fan relay and the resistor. What else could the problem be – The Switch, the blower itself?

Winter is here in the NW and it would be nice to have the high speed to defog the windows.

[jhow66]

Trace the red or orange wire off relay back to your fuse panel. There are a couple of connections near the plug in that get loose and heat up causing a poor connection.

[chickenwing]

hear the relay workin?

[bouncytruck]

I'll double check the plugs into the fuse panel, but everything works but high speed.

Where is the heater relay? I just replaced the high-speed fan relay (located on the far left side of the A/C box, under the glove box.)

[Longhorn Man]

That is the heater relay....same animal, different name.

[bouncytruck]

So, what else could it be?

[Hutch]

bouncytruck
It could be the ground wire to the relay that is located behind the glove box near the side panel.
It is up pretty high on the inside firewall.
If this is your issue the fan will work on high just at a very slow speed.
It is a short black wire that goes from the relay to a ground.
This is usually one if the bolts that hold the heater core case on, this wire will get broken due to it being such a short wire or misplaced when someone swaps out the heater core.

[jhow66]

As Hutch says. Just take a jumper wire and hook to relay and then to a good ground and test your high speed. If it works you found yor problem.

[71Shortbed]

Mine did that and the switch was bad. Apparently it was not grounded very well and overheated causing it to burn the internal connectors. It worked on all speeds except high speed was intermittent. Swapped it out and checked all the grounds and it's been working fine.

[Terry Peerson]

Trace the wire that goes to your cigarette lighter. It also supplies power to the high-speed fan. I think mine went directly to the fuse block. No relays here. Mine was simply disconnected.


T

[bouncytruck]

Thanks for all the input. I'll give each these a try.

[neonlarry]

You obviously have power to the switch (the other speeds work). If its not the relay ground I would bet on the switch. GM under designed that switch. I have had to replace all of mine, they were toast.

[Terry Peerson]

Actually, the High-Speed Fan power is supplied separate from the two other speeds. It is the big orange (I think it was orange) wire that goes to the cigarette lighter that only powers the High-Speed portion. So, the fan can work on the two lower speeds with there being no power to the High-Speed, at all. I don't think mine even has any relays or fuses in the wiring, either. It goes directly to the fuse block.

TP

[bouncytruck]

Hum, My cigarette lighter doesn't work either. I wonder if this could be the problem. I'll be doing a little wire tracing and trouble shooting this weekend (it's too dark when I get home).