My fan speed switch isn't working on the first few settings. It only works on the highest setting. Sometimes they all work, and sometimes they don't. This has been occurring over the last month and I can't figure out what is going on. If anyone has any suggestions on what I should check to correct this it would be greatly appreciated. (2008 Model)

Update:
A big thank you to jbob! It was the blower resistor. Very easy to replace. Only takes about 10 minutes. I will post a link that will give you a step by step guide on how to repair this little situation.

HVAC blower motor resistor replacement
This is how I replaced the HVAV blower motor resistor in a 2005 Tacoma.

Symptom of a bad resistor for me has been that the AC/heater blower will only work on high. At first this is intermittent, then later pretty much constant.

First let me say that this is the 3rd resistor for this truck. They seem to last me about 18 moths. The first replacement was under warranty, and after they checked everything else out they decided to replace the resistor. Once they decided it took the guy 15 minutes or so to replace it. A few days ago I called the local stealership, the service estimate was 1 to 2.5 hours labor and $38.17 for the resistor (MSRP $28.89). That's why I decided to do it myself.

The first problem is finding where the darn thing is. By looking at the service manual it appears to be next to the blower motor, actually it sits right next to the firewall a little to the left (drivers side) of the blower motor. Now a skinny little guy could get to it rather easily, but for a big old fat guy like me (59, 6’6”, 325lbs) that isn’t at all limber - not so easy. I tried to get up under there but just couldn’t my head and shoulder jammed in enough get a good view.

I ended up pulling the front passenger seat for access. It still isn’t easy - but at least do-able.

Now that I know where it is I believe that I could change it without removing the seat.

First step after you find it is to disconnect the wiring harness, it comes off pretty easily, next there are 2 screws holding the resistor in. There is one on the left as you look at it, there is a second one on the right in about the same position - but on the back of the unit and pretty much not visible. I couldn’t see it no matter how far I got under the dashboard.

You can feel it though. You will need a 5.5mm socket on a ¼” drive ratchet. It needs to be a ¼” drive because anything bigger won’t fit on the back screw and in the space available. As it is I had to pull the carpet out of the way to get on the hidden screw.

Just last week the blower in my 05 would only work on high. I usually leave it on low all the time so I quickly turned it from low to high a few times and it started working properly and has been fine since then. I'll be bookmarking this just in case it screws up again.
Thanks for the write-up.

A faulty pigtail(connector) on many tacomas is common the only problem is its part of the dash wiring harness and can NOT be spliced. The connector is the one plugging into the resistor block. You will be able to see if it is a bad pig tail, it will have discolored or darkened insulation on one of the wires on mine it is the second from the far right when its plugged in.

It is NOT spliceable since that wire comes from the A/C amplifier and its a computer looking at voltage and resistance values.

The stealership Fix over $1240.00 for a new dash wiring harness plus 5 hours labor at 125.00 per hour.
My fix pull apart the connector and slowly remove the one terminal that is damaged from the connector pack. Once you have done that tighten up the terminal so the terminal pin on the resistor block will make better contact. Reassemble the connector and plug it in. This is the more permanent solution the stealerships don't want you to know.

btw kbmcmahon in those photos it looks like the terminal connector cavity in question is brown (burnt). I believe when the resistor is replaced one gets lucky for awhile because connection is restored, not a bad resistor. If a resistor is opened, check it with an ohmmeter for continuity from the power in terminal (the one that burns) to the outputs. These resistors are pretty rugged looking in design to me.

btw kbmcmahon in those photos it looks like the terminal connector cavity in question is brown (burnt). I believe when the resistor is replaced one gets lucky for awhile because connection is restored, not a bad resistor. If a resistor is opened, check it with an ohmmeter for continuity from the power in terminal (the one that burns) to the outputs. These resistors are pretty rugged looking in design to me.

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Good pic of the connector end...I was wondering about the actual resistor body, the part that sticks up in the cavity.

Notice the white wire w/blu tracer - that is the voltage supply wire - it is bigger than the others, but the terminal connector is the same size; that is the problem. Too small of a terminal for the amperage flow for med-med high blower speeds thus it gets hot and the heat causes the terminal to create an oxidation when it cools down and a poor connection (ever seen the black carbon on a battery cable terminal? Much the same).

Notice the white wire w/blu tracer - that is the voltage supply wire - it is bigger than the others, but the terminal connector is the same size; that is the problem. Too small of a terminal for the amperage flow for med-med high blower speeds thus it gets hot and the heat causes the terminal to create an oxidation when it cools down and a poor connection (ever seen the black carbon on a battery cable terminal? Much the same).

Click to expand...

Exactly what I was looking for--thanks!

I wonder whether using something like Deoxit or Stabilant 22A (electrical contact enhancers) would help with this issue. Or possibly even just dielectric grease, if done when the contact is still in good shape, might prevent oxidation.

The dielectric grease might help. But I believe the best fix would be for Toyota to make an updated resistor with larger terminals and an updated connector pigtail that could easily be spliced into the harness.

I had the same problem and got a new resistor from the dealer. the day i got it i just threw it in my counsole to replace later and havent had problems with the fan cutting out since. the easiest fix ever.