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Old Mazda 626 LX with heater blower problem

 
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Papi_dlg Papi_dlg
New User | Posts: 2 | Joined: 09/11
Posted: 09/18/11
05:08 PM

I have a 1988 Mazda 626 with a heater/AC blower that stopped working.

First the low speed and high speed was the only speeds that worked and then only the low speed, and then they all stopped.  I replaced the motor resistor.  The old one had broken coils.  I put it all back together and still the blower doesn't come on.  

History:  Before I did anything the indicator light on the dash for the AC, only lit up when the blower was set to low speed.  When I moved the sliding switch to any other speed, the AC indicator light went out and those speeds didn't work.  After I replaced the resistor, the AC indicator light now lights up on all the speed settings, but no blower.

I ran 12V directly to the blower motor and it works fine.  I checked for voltage going in to the resistor and I have it, but the leads going from the resistor to the blower motor do not have any voltage.  Just to be sure, as I said before, I have 12V going "to" the resistor so I hooked a couple of jumpers going from that 12 volts directly to the motor and it won't blow.  That blows my mind because in my mind the voltage that my voltmeter shows going into the resistor should make the blower run, right?  Am I missing something here?  Is this a ground problem?  

I am desperate here.  I replaced the resistor which was obviously bad (broken coils) and thought my problem was solved, but the blower still won't blow.

Somebody please help!

Regards,  Don  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 09/18/11
06:39 PM

the blower switch is probably bad..

on high.. the blower resistor is usually bypassed..

on almost high.. a different circuit through the resistor is active..

on medium..   a different circuit through the resistor is active..

on low..    a different circuit through the resistor is active..

on positive vent... which is anytime the key is ON...  it runs through a different circuit..

let me take a look over at AZ.. see if there is a diagram for the blower...  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 09/18/11
06:49 PM

here are a few diagrams that might help..

0900C1528004ec43

~~~~~~~~~~~~~
this one shows the AC blower wiring..


0900C1528004ec44


these might help...  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 09/18/11
07:07 PM

now that i described how it worked..

the second diagram shows it backward..


the blower motor is powered via the blower motor relay..  it gets hot at all time power from a 40 amp main fuse... (will have to print the upper diagram for that section..)


the blower switch has the movable contact grounded..    so when moved off position 0 to position 1.... it goes to LOW and through 4 sections of resistor..

when it moved to position 2. it goes through 3 sections of the blower resistor..

when moved to position 3.. . it goes through 2 sections of the blower resistor..

when moved to position 4..  it bypasses the blower resistor completely..   if you noticed the electronic load control unit.. that is what causes the blower to run at a low speed.. even with the switch is off.. so it keeps a positive pressure inside the car.. to keep the fumes out..  

Papi_dlg Papi_dlg
New User | Posts: 2 | Joined: 09/11
Posted: 09/19/11
03:45 AM

All of this information is great!  However, I failed to mention that although I understand electric circuits, I don't have the knowledge to completely understand the drawings you've provided.  I have good general knowledge, but not really specific to this situation.


I also understand your exlanations, and being that you seem to have a great grasp of the diagrams, can you answer the question. Please have patience with me.  With a new resistor installed why do I not get current coming from the resistor to the motor even though I know I have current going into the reisitor?

Could the new resistor I bought be bad from the factory?   I'm thinking to myself, power in, power out, right?  Where is the break in this picture that prevents current from going to the blower, when I know I have current going into the resistor?  Also, it was mentioned that setting the blower on high bypasses the resistor completely so the motor should work on high in any case, but it doesn't.  Does That indicate that the sliding blower switch is bad then?

Also the diagram shows a blower motor relay with a blue wire going to the motor.  My motor doesn't have that wire.  Only two wires coming from the resistor to the motor.


No other explanation.  

Don  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 09/19/11
04:40 AM

print both  pictures/diagrams... or open it in a new window...

the blower circuit is off on the right side and cannot be seen....


the blower motor relay supplies positive power to the fan motor... as soon as the key is turned on.....  do you have power there when the key is turned on????   if not.. you will need to check the fuses under the hood.. and find the blower motor relay...

the power to the blower is either OFF when the key is off.. or ON when the key is on...


the blower switch... connects to the various leads from the blower resistor... this controls the speeds of the blower...

but the blower switch .. has the contact grounded..    

it takes both a positive and a negative connection for the blower to work..

ben franklin got it wrong.. electrons flow from negative to positive..


once you see the blower section of the diagram. it should make sense...  

mikewol3 mikewol3
New User | Posts: 5 | Joined: 10/11
Posted: 10/01/11
04:14 PM

I am having the same exact problem with my 1988 626. I am unable to find the relay fuse for the blower motor anyshere, and I have the shop manual. You say it is a 40 amp relay under the hood, yet the diagram you provide does not have any.  

mikewol3 mikewol3
New User | Posts: 5 | Joined: 10/11
Posted: 10/01/11
04:15 PM

I am having the same exact problem with my 1988 626. I am unable to find the relay fuse for the blower motor anyshere, and I have the shop manual. You say it is a 40 amp relay under the hood, yet the diagram you provide does not have any.  

mikewol3 mikewol3
New User | Posts: 5 | Joined: 10/11
Posted: 10/01/11
04:16 PM

I am having the same exact problem with my 1988 626. I am unable to find the relay fuse for the blower motor anyshere, and I have the shop manual. You say it is a 40 amp relay under the hood, yet the diagram you provide does not have any.  

mikewol3 mikewol3
New User | Posts: 5 | Joined: 10/11
Posted: 10/01/11
04:18 PM

I am having the same problem. Where under the hood is the 40 amp fuse located. I see nothing markded for the blower and all the fuses look good.  

mikewol3 mikewol3
New User | Posts: 5 | Joined: 10/11
Posted: 10/01/11
04:18 PM

I am having the same problem. Where under the hood is the 40 amp fuse located. I see nothing markded for the blower and all the fuses look good.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 10/01/11
04:55 PM

like i posted above..

open each of the 2 images in a new window..

print them...   the sections you need are off to the right side and not visible ... it will be when you print it..


if you can read the diagram....

the fuse supplies 12 volts positive to a relay that is controlled on or off...


the blower motors ground side runs through the blower resistor... and that is split into three or 4 wires... the blower switch connects one of those at a time... to ground to change speed..

this is reverse of what most people would expect to find it wired up as...

print the diagrams above..  you may understand it better..  

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