The readings were all around 12v. Whatever the battery was at except for those reading only mv's....

87a did not change with the selector

 

Lets start with the fact that you have lost always on 12v power on socket 87 which is why the highest fan speed stopped working. If the 30A HVAC fuse in the UHFB is good then pull that fuse and measure the voltage in both sockets.

Also, measure the voltage on 87a in all 4 fan speed positions.

Lastly double check 85 because that should be ground, not 12V.

George

 

Blower does not come on when power applied to socket 30...

 

I will start all over again...


Maybe if you could tell me what each pin does I would understand a little better...


So are we leading up to a blower malfunction or something other?
Since I tried a new selector, installed new resistor and tried a new relay. Just don't see how the fan could just quit from some other malfunction. By the way, if it makes any difference, I have the whole dash torn apart and stuff hanging everywhere to try to tackle a multitude of problems...

 

OK, I will explain the reason for each step as we go along and you can follow along with this circuit diagram. Lets go one step at a time:

Socket 30 goes to the positive lead on the blower motor and the negative motor lead is a permanent ground. The fact that fused power on 30 does not start the motor says that either the motor is dead or there is a wiring problem between socket 30 and the motor or the motor ground. If the motor connector is accessable, disconnect it and apply fused power and a good ground and see if the motor starts. Lets get this section resolved and then see what else is still not working properly. Based on what you have told me so far there may be some corrosion or damage in a wiring harness or under the fuse box but lets see if the motor and its wiring are good first.

George

 

So I guess we should have started here first. The blower motor is dead running it direct to the battery. The harness is getting power when I jump the 30 socket. Seems even brainless me should have tried that! But it seems the way the motor quit in groups, all the diagnostics were leading up to the resistor or the relay. Oh well. Only one gentleman on this thread tied those symptoms in with the motor itself.

At any rate, I did all the tests all over again. I had some terminals mixed up looking at the inside if the relay vs. the harness. So time for a new blower along with all the rest I got going on.

Perhaps a moot point at this point but here is what I got:

87- constant voltage 12.2v
87a- ign. voltage 12.2 v all selections (1-4)
85- 5.2mv all selections
86-0.3-190.0 mv selections 1,,2,3. 12.2 v on selection 4 (mv continuously fluctuated)
30 jumped to bat. no fan
UH fuse 12.4 v left side/ 0.3-190.0 mv fluctuating
blower motor dead jumping + and - direct to battery

So thank you for your time. We will see what a new motor brings.

PS On top of it all, my printer is dead so had to bring the computer out to the car to read your diagnostics. And my battery was dead this morning because I left the ignition on. I need a beer....................

 

Thanks for the input. It seems that the blower motor is dead. All other threads seemed to point to the resistor and relay. I should've gone straight to the motor first...

 

Bad blower motor can damage wiring and relays and connectors.

 

I think that the reason it failed in stages is that lower voltages were not able to get it turning first and then even full power would no longer get it moving.

It does not matter what end you test first. Once you are proficient with a meter and a diagnostic mindset you can follow the entire path in 15 min and have your answer. Its a little clunky doing it this way remote control working with people of unknown experience level but we got it done.

The reason that I often start at relay sockets and fuses is because all test points are easy to get to and it usually cuts the problem in half.

BTW, one of the reasons that I advocate tesing to find the fault and replace the targeted parts is expense but also, in many cases you are replacing perfectly good high quality OEM parts with inferior quality after market parts with a high failure rate.

George

 

Logically you can start at motor end of circuit or the other end :battery / fuse box / switch end or in the middle at the relay . But as George mentioned once you get familiar with using a meter and basic circuit layout , it doesn’t take long to narrow down most electrical problems no matter where you start in the circuit . And the goal of most everyone on this forum is to help diagnose properly and save money and keep from replacing good ( maybe oem ) parts with possibly bad aftermarket ones and be out the cost twice . And since sometimes a new part is actually bad, just replacing the resistor or other part doesn’t always rule that out as issue . So learning diagnosing with a meter will save time and money . I usually even power up the blower motor before installing just to be sure the new part works and isn’t noisy.

Your original post just led me to think either blower motor or resistor . Both can be checked pretty quick with a meter at blower motor terminal . Resistors generate heat , that’s why ballast resistor is placed in air box to dissipate the heat, so often when motor quits the resistor burns up too from lack of airflow . And often when a motor goes bad it can burn up relays , wiring , connectors and fuses too. The more you do and learn, the better you’ll get at diagnosing .
The blower motor is a pretty basic 12v DC motor that varies speed by lowering voltage switching through a series of resistors, with high speed being accomplished with a relay that removes the resistors and sends 12v direct to motor . As the motor ages or bearings wear out it has trouble starting at the lower voltages (speeds) and eventually even 12v on high won’t make it start. When relay goes bad it usually either will only have high speed ( relay stuck engaged ) or will have no high speed ( relay coil bad) .

We all are just glad you know the problem and what to repair to fix and get her going again !