AC, blower no go

Hi folks, I need hellllllllp!
My 2006 quad cab limited just decided to not blow cab air anymore. It was working fine when I got home one night. Then going to work the next morning, I suddenly had no blower. It was only 19 degrees out so a little warm air would have been nice. Anyway, I have checked every fuse, and relay, they are all good. I replaced the resistor and still nothing. I have pulled the blower motor, put power to it and it purrs quietly like brand new. So, I guess I need a tutorial on how to check the harnesses. There is no evidence of any wear that I can see, all plugs are nice and clean. I have also noticed the A/C button light does not turn on, nor can I hear the A/C clutch kick on. If anyone out there has a clue as to what I can do and how to go about it
Please fill me in.....
Thanks

 

Was this a random occurrence, or was there a recent repair or mod of some kind? Does sound like it's not getting power from the harness. Not sure how you checked the fuses or the relays, but swapping the offending fuses for new may be worth a shot, even if the old one "looks" ok. Any water intrusion into the cab? The windshield cowl mounting tabs tend to leak water. Check for damp carpet in the passenger footwell and kick panel. Another more remote explanation could be damage to one of the harnesses, by a rodent perhaps. The harness that plugs into the center console trim is a good place to start tracing the wires and looking for problems.

 

Yep

 

Thanks, I will do my best. It sounds like one of those easier said than done things.

 

Also if you pull straight out on the fan speed knob you’ll notice it’s a square. If the knob cracked it could be turning to a different speed while not actually turning the actual shaft it sits on. Easy way to check is pull it off and swap with one of the other two knobs

 

Hey I’m having the same problem and was wondering if you ever found the problem?
Thanks in advance

 

Yeah, I doubt dude is gonna answer... Sadly, another guy that only came here for a solution, the shit his way right back out the door. Typical.

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Tell us more about the symptoms you're having.

Like, is the fan only blowing at one speed? Or no fan at all? All fuses in the dash are good? Did anyone do maintenance recently that had the center dash out, like a radio install?

 

2005 Double cab limited.
So compressor, filter and expansion valve replaced little over a year ago. So this week driving home A/C working fine, stopped at store came out no fan and no A/C light. Have checked all fuses and relays. Have power to blower switch, tried different blower switch no luck. Blower motor works when I give it 12 volts. I’m not great at electrical but any suggestions I’ll try.

 

Thanks for quick reply!

 

Well, based on what you're saying, it sounds electrical. Near the top of this thread, about 4 or 5 lines in, you'll find likes to electrical wiring diagrams (EWD) and service manual. https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

It may help you with this. I'm not familiar enough with the wiring in our trucks to immediately understand the problem. But I have my suspicions, based on what you're saying, the HVAC control is toast. And unfortunately, that's not a part you can just go to a JY and pull one out of any year/cab type, and bolt into your car. Just for the 2005 year, there's probably 3-4 different part numbers for that control unit. They're not interchangeable.

 

When you say HVAC control unit I’m not sure what you mean. I didn’t think 2005 had a control unit or module?
If you can give me an idea of what you mean I can figure it out.

 

The physical circuit board and controls living underneath the knobs in the dash.

But much of it is lumped together, under the white cover you see here, click here for more images. You said above, unless I misread, you've already been in there testing, hence how you know the dash switch gets power. There's basically a dedicated circuit board for climate control under there, IIRC.

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Got it, I bought all of that from a Pic and pull but only tried blower switch… I’ll try all the other plugs and see if I have any luck. Thanks for pics and info.

 

Like, you bought a replacement control from a Junkyard, and that's the one that's giving you probs?

If so, that's your problem. There are at least 4 different control modules for the 2005 year, and not all of them have the same circuitry inside of them.

 

I'll assume the circuit board being mentioned(Integration Control and Panel) is shown in below pic.



I realize what you said about fuses/relay but just to be sure....you checked the 10A GAUGE, 50A HTR and 10A A/C fuses and also the Heater relay is indeed energizing.

Seems odd but ask anyway. Does the blower motor work if switch is placed in High position....thinking resistor circuit which is not used in High setting. Also, the selection switch is not in defrost setting at any time correct ?




I have also attached the 3 pages from EWD associated with 2005 AC....A/C wiring

 

Okay plugged in used unit in with same results. No blower at all and no A/C light. All other lamps and switches worked. Have checked every fuse but not sure which plug in Heater relay should be energized. Sorry it’s taken a couple of days. I will be studying wiring diagrams, and thanks for those.

 

Htr relay is in Engine bay....

 

Well after going around my thumb to get to my A$$, turned out was just a bad relay. I know they don’t fail often but once again check the easy things first. Heater relay under hood. Thanks for all the responses. Hope this helps someone else.

 

I have to update… Not bad relay… Bad connection in heater relay. If you have this problem check for discoloration at heater relay. Bad connection!

 

Hello, I’m having the same problem.. no fan when I switch on the heater no ac light when I push the ac button. I replaced the relay and still no go. You said it was the heater relay connection? How did you fix that? Thanks in advance for the help.

 

The relay was not making good connection at 12 volt source so bent the blade on the relay so it would make a better connection. I’m sure there is a better proper way but it has been fine for months.

 

@rundaT 06 have you checked for power at the relay socket itself? If the socket has no power, the relay can’t do shit

 

@slooburn dang I wish that was the issue for me but that’s not it.

 

@shifty` good question, that’s actually the next thing I checked. I did the test on the relay socket and it isn’t getting any power. Oddly enough three of the fuse’s surrounding the relay also aren’t getting power. I’m stumped. I used the info I found in this video to test the relay socket.
https://youtu.be/xiaqTfl2ZZE?si=5EIclRH2WbITwc5P

when I hook my test light to the negative battery cable and test the pins in the relay circuit none of the pins make the tool light which leads me to believe that I have no energy coming from the load side.

Do you know why there isn’t and power going to the relay socket and some of the fuse sockets?

 

Time to hit this thread and grab the EWD (electrical wiring diagram) for your truck from the links in the 4th or 5th paragraph so you can trace back those circuits. Multiple circuits? I suspect a fuse in the fuse/relay box, maybe.

https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

If you have trouble fishing it out, I'm not your guy. I hate the way the EWD are laid out for these trucks and have a hell of a hard time reading them. I hate to ask people really stupid questions, but we can't assume anyone does basic troubleshooting, so ... did you bother checking the fuses in the fuse/relay box under the hood? Specifically the two fuses on the right here, which it looks like are for HTR and A/C, from pic Bubba posted above? Although that bottom one looks like it may be a diff't kinda heater.

 

Correct, that A/F HTR fuse is protection for the A/F Heater circuit(air/fuel O2 sensor)

@rundaT 06 , since the AC fuse/relay panels are significantly different from a DC fuse/relay panel, which cab do you have ?

Do not want to assume wrongly but did you have key in IGN ON with blower motor switch in at least LO position ?
As noted in description below, HTR Relay pin 2 will not have voltage unless IGN ON/Blower SW LO

My suggestion is to revisit your voltage checks, have meter negative lead to a known good gnd(battery preferably), with HTR Relay removed, check pin 5 for a presence of 12vdc present at all times. If no voltage, need to address that issue first.

If pin 5 does have voltage, place IGN ON/Blower SW LO, does pin 2 have 12vdc ?

If unsure which is pin 5 of HTR relay socket, keep in mind on our relays the relay coil 2 terminals are smaller in size compared to the 2 relay contacts. Hence the HTR relay coil is protected by a 10amp fuse vs the HTR relay contacts protected by a 50amp fuse. One of the 2 bigger contacts of socket shold have 12vdc at all times.

 

I don't want to derail this thread, but...isn't there a blower motor resistor in this circuit?

 

There is indeed but according to @rundaT 06 checks, the HTR Relay is not energizing. The resistor portion of HTR circuit does not come into play until after HTR Relay energizes as noted in System Outline in above pic.

 

Not only that but even if the resistor is bad or uninstalled, I would still expect two speeds: OFF and either HIGH or LOW, depending on the vehicle design itself (speaking generically on purpose).

It is what it’s named: A resistor. As long as the circuit isn’t open (broken somewhere) you should see some native* resistance in the circuit if the circuit is closed, thus some fan movement. In our trucks I believe those speeds are OFF or FULL blast if my memory service from when I pulled my resistor out totally.

 

Correct - off or high.

This thread has 3 different folks all the with same problem? OP seems to have bounced and now we have two more unlucky souls - both with doublecabs.

Do you guys: rundaT 06 and slooburn, both have the FSM downloaded? This'll require chasing the EWD for your cab (DC). This would be good to confirm first and then a a quick reply to the thread with an update with what you've tried so far and where you're currently at. This will help us all immensely. I'll be rolling my sleeves up.