Broken Heater/HVAC... Replaced blower motor, resistor & relay. STILL NO AIR!

eriksseven

Your local RX-7 guru...
*FIXED* Broken Heater/HVAC... Replaced blower motor, resistor & relay. STILL NO AIR!

So this is getting really annoying...

One morning I started my car and my heater wouldn't turn on--no air, nothing. I left the console controls ON at setting 4 even though it wasn't working. After driving for several minutes it *magically* turned ON and I was greeted with a nice blast of hot air.

I assumed a finicky Mazda electrical system was being affected by the cold weather.

For several days this happened. I would start the car, drive until the cabin was somewhat warmer and then *BOOM* the heater would "fix" itself and turn on.

Sometimes I fiddled with the control console dials when it wasn't working. Leaving it at 0, then twisting it to 1-2-3-4 and back, or switching to defrost/main-vents/feet etc. trying to see if I could get it to activate. Several times it would turn on during my *fiddling* or if I hit a sharp pot-hole in the road.

Then one day it never came on. It has been broken completely for over a month now.

I replaced the Blower Relay first. Nothing. I then replaced the Blower Motor--hoping to go for the jugular. Nothing. Finally I replaced the Resistor--even though I was certain this was not the problem. Nothing.

Ugh. Replace the console controls next?

Any advice?
 
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pcb

The Diagram Dude
:
2002 MP5
I would try tracing the power through the system,... see if you've got 12 V in and out of the blower relay, fan switch, motor and resistor. It sounds like a bad connection somewhere. (That fan switch is crap too,... it's part of the flickering AC switch,... too many amps running through it,... maybe try bypassing the switch with a jumper there may be no contact inside it. Check the connector at the back of the switch for melted plastic and bad connections)
 
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pcb

The Diagram Dude
:
2002 MP5
Try getting the fan switch connector off and putting a jumper wire from the fat black wire input to one of the fan speeds,... that would bypass the switch and should fire up the blower.

http://www.mazdas247.com/forum/attachment.php?attachmentid=113589&d=1186177603

If you end up taking your switch apart, be aware that there is a little spring and ball bearing inside that go flying when you open it. (they allow the switch to 'click' into each fan speed.) My AC light started flashing and I ended up taking apart the switch and cleaning it up with fine sandpaper and that managed to stop the flickering AC light. I put a bit of grease on the contacts and a dab on the spring and ball bearing helps to hold it in place while you re-assemble the switch.
They finally made a revised switch for the car late in it's production run and there is a part number for it somewhere in the AC thread I think.
 
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Installshield 2

Gothenburg Superiority
What happens with control switches? I understand the blower obviously isn't blowing anything, but... If you press the AC button, does the light turn green, can you hear the compressor kick on?...does the light turn off if you move the fan speed selector to 0? Does it not turn green with the fan speed in any position? lastly, do you get any illumination through the HVAC controls by turning the head lights on?

and what about the circulate/vent option? with the car key to 'on', but the engine not started (so that you can hear it)...does the flap move when you press that selector?...and do the lights for that selector work (green for fresh air, orange for recirculate)?...

It sounds like it may be the HVAC control board...which are notorious already for giving the 'flickering AC light' thing...there are some how to's to permanently fix that, or you can buy revised units online (cross over motorsports sells the OE revised part, but its nearly $300)...i'm not positive this is the issue, but considering those things already get messed up with resistances and stuff...i'm pretty sure its something to do with that circuit board...

but make sure by removing the HVAC panel, and go over the harness connector behind it...if that has some corrosion built up or something, that may be all it is...this would be the case if you're not getting any lights through it...as its the only wiring to physically connect the HVAC physical controls for AC, recirculate flap, and fan speed to the ecu to receive power...it seems like the fan speed is the biggest culprit, as it will override the AC button if its stuck at speed 0...even if only some of the pins are messed up, it would be a good place to start with cleaning that connection up as best as possible...simply to rule it out...
 

pcb

The Diagram Dude
:
2002 MP5
^I'm willing to bet ten bucks to a nickle that it's the switch itself. I couldn't believe how 'light weight" the components were inside and that switch is dealing with something like 12 amps on fan position 4. All that power is running through a paper thin pivoting contact plate inside with only about one square mm of actual contact. The plate is kinda spring loaded which weakens over time and mine was all covered in black crap and not making good contact. If that plate doesn't make contact internally no power goes through the switch and the blower won't go. If he jumpers a wire at the fan switch connector, he can see if the blower spins up. He could leave it jumpered at say fan switch 2 so at least he has some heat while he fixes or replaces the switch. He can't really go wrong with the jumper as long as it doesn't ground out any where, that would be a dead short. Tape it up good before you turn the ignition on.
I'm not sure about the green light but I think it's powered by the switch (as well as that sensor wire too). If that switch is pressed, it doesn't illuminate until the fan is turned on, so i believe the fan switch powers the HVAC control circuit. The recirculate lights are still lite when the fan is off so I think that part is separately powered. So I'm thinking nothing but the recirculate switch operates if the power isn't getting through the fan switch.
A tiny bit of resistance (say 1/4 ohm or so) across a bad connector or dirty switch contact generates huge amounts of heat when there is 12 amps running through it. Some guys had pictures of melted connectors on the back of their fan switch, that combined with the fussy sensor wire for the control circuit (that 1/4 ohm again) leads to lots of problems with our HVAC system.

http://www.mazdas247.com/forum/attachment.php?attachmentid=148730&d=1240844102

http://www.mazdas247.com/forum/attachment.php?attachmentid=148985&d=1241198092

http://www.mazdas247.com/forum/attachment.php?attachmentid=148983&d=1241198070
 
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eriksseven

Your local RX-7 guru...
The illumination/flapper switch/rear defroster all work--just no blower fan. Really feeling empowered about this issue! I'll bypass the switch tomorrow and let you guys know what happens.
 

eriksseven

Your local RX-7 guru...
Try getting the fan switch connector off and putting a jumper wire from the fat black wire input to one of the fan speeds,... that would bypass the switch and should fire up the blower.

The fat black wire was fried to all $hit. Broken, charred brown plastic surrounded it. When I undid the plug, little pieces flaked off... Fat black wire was swollen and rock hard, blackened on the copper.

I scraped the connection spades and harness, ridding it off the blackened bits and cleaned everything. Then I put the plug back together, put the car ignition to ON and like magic, BOOM! The fan I haven't heard in months hummed to life!

Stoked! Thanks for the tips guys. Nailed it!

~Erik
 

pcb

The Diagram Dude
:
2002 MP5
Glad to help,... Now to figure out your next step. That revised part that Installshield mentioned sounds pretty steep at $300, but the 'flickering AC' thread covers all your options. That swollen rock hard bit of wire would make me nervous.
 
:
Lancer Ralliart Sportback
Consider replacing the wire itself if all you did was scrape off the charred bits. That broken down insulation is all that keeps the car from catching fire if you think about it... Also - broken insluation lets in moisture and grows corrosion - which increases resistance (and heat) - see the fire warning (above).
 
:
Mazda Protege5
i followed the instructions and i got no change. it didn't work. maybe I'm not getting something but it seemed pretty basic.
Sorry, wrong thread...I meant to post this thread at a different location.
 
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pcb

The Diagram Dude
:
2002 MP5
Did you check your connector and the internals of your switch or just do the resistor 'trick' ??? The resistor trick won't help if your connector is burnt or your switch internals are dirty and carboned up.
 
:
2003 Mazda Protege 5
I Know this threads been silent for a bit but.. I'm having a similar problem. No air from the blower. No green AC light. But the Fresh/Circulate switch still lights up and DOES work. I can hear it humming for a few seconds after pressing it. After about 5 months of No blowing air. I was able to get air moving (heat) while on a low setting, between 1 and 2. I tried changing the blower motor resistor but that didn't solve the problem. Made it worse actually Now I have no air movement even on the low setting that worked previously.

I haven't changed the Relay or the actual Motor yet. Just wondering if anyone has an idea. InstallShield had some questions about the OP which I think I answered. Trying to take out the switch itself maybe in a day or so..

Other than that, has anyone had any experience with this taking to a shop? What was the Problem/Cost?
 

pcb

The Diagram Dude
:
2002 MP5
Check behind your fan switch for this:

If your switch is burnt bad enough, you will have no blower.

PANA0160_zpsdfecf552.jpg
 
:
2002 Protege5
Just cut he wires and use these...





The wires tend to be burnt and crispy for a couple of inches anyway...

Got it....any way to say what size those are? I'll probly have to order online, and I'm seeing an ton of size options...thx!
 

pcb

The Diagram Dude
:
2002 MP5
Got it....any way to say what size those are? I'll probly have to order online, and I'm seeing an ton of size options...thx!

I don't know what size... They are kind of standard... The smaller ones area lot smaller.

You can remove each 'clip' from the plastic connector... Use a pin on the wire side of the connector to unhook it.... There's a litte release tab...

Radio Shack or even hardware stores should have them...
 

pcb

The Diagram Dude
:
2002 MP5
I like my fix...I've had no problems...





I'll make you one... 50 bucks... (American)... Plug and play...

(you just have to clean your switch...)






 
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