I have been trying to bring an 1999 Mazda Millenia back to life. When I got it the Heater and A/C controls was stuck at 77 degrees. I replaced that unit with another from ebay, and now I can change the controls.

During this time the fan would never blow. Even after replacing the control unit the fan would not blow. I assumed the fan itself had failed, and ordered a replacement. The new fan will not blow either. When I measure the voltage feeding the fan I get about 14 volts from one wire, and 6 volts from the other wire when measured to ground.

The fan does not blow regardless of the selected fan speed. Any help is appreciated.

 

It sounds like you are getting power but not ground. Since it is a two wire connector just put your test light on the connector jumping the alligator clip with a paperclip to one terminal and the other end of the test light to the other terminal. It uses an ac amplifier to control the ground on the blower motor for blower speed. Unfortunately the ac amplifier is the ac control unit. Likely the blower motor was frozen up from non-use and fried your replacement ac control unit. You will need to find a wiring diagram and test the ac amplifier input/output for ground variance.

 

the amp/control failure is common for this car. we have 2 99's, and i have changed out the assembly at least twice on both cars. you have to be careful with ebay stuff. the last amp i bought came from a car that was under water. everything was corroded badly. these units used to be about 25 bucks, and i think i still have 2 that i bought off ebay way back when, and i tested them to make sure they work. the corroded one i bought recently off ebay, because it was from the later model year, and i wanted to see what the difference was. while the pushbuttons are identical, the amp part is smaller, and the connectors are different. actual blower failure is really rare. i would bet the one you got is also bad. i would return the ebay one and try another.

 

While it is true that the AC amplifier failure is not uncommon it is always caused by blower motor excessive amperage draw. I have never,nor will i ever replace an AC amplifier without replacing the blower motor whether it is actually working or not. If you took your blower motor apart you would see why they draw excessive amps as they get older.

 

both our cars have 150k, and are more than 15 yrs old. both still have the original blower. both have had the amp changed out at least twice. i still have a spare blower i bought years ago. the amp is way easier to change than the blower, and if you can find them for cheap, i would just change it, and not bother with chasing voltages. i have repaired a couple amp/contols by using parts from others, but just out of curiosity. there are some problems that are unique to the millenia, and also some problems that are unique to the 2.3. i recommend checking the other millenia site, mazdaworld.org, go to the millenia section. there is a lot more technical info there than on this site.

 

I worked for Mazda over 20 years in Houston. I can say with absolute certainty that a blower motor can work just fine but draw too many amps and destroy sensitive circuitry. The voltage is not the problem,amperage draw is what destroys circuitry. Cause and effect are universal. You can certainly replace your ac amplifier over and over and over and over and blame it on the ac amplifier but it is the blower motors fault,not the ac amplifier.

 

Thanks everyone for your input. I have ordered a replacement ac amplifier and will update everyone with whether that resolves the issue.

 

yah? working for mazda for 20 years only means you have worked on a lot of mazdas. how many were customer pay? there are lots of posts not only on this forum, but on others where the amp was changed out, and that fixed the problem. i have NEVER seen a post on the blower destroying the amp.

i only post on my personal experience with the millenia, what i have done, and what i have seen on mostly the other forum. what others want to do is their own business. and just because someone has worked at a dealer dont mean they know everything. where the millenia is concerned, all the posts i see, and my own personal experience with the dealer, is massive overcharges, diagnosis by the guess method, and a whole lot of parts installed that do not fix the problem.

 

Lol, 3/4 of the work in Houston is customer pay. People want their cars right and not on the side of the road in rush hour traffic. You can replace just the ac amplifier and it will appear to be fixed. It will however slowly overheat the ac amplifier and destroy it. That said, I never agreed with their integrating the blower control module into the heater control module. They should have isolated it with a blower resister just before the blower motor. The ac amplifier is too sensitive/expensive to pull large amounts of amperage through. It however is what it is. The more worn the blower brush's are the more amperage it draws. On most systems that is not a problem.