× Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

AC blower pulling voltage down

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
06 Jul 2019 22:21 - 06 Jul 2019 22:54 #31466 by jerry r
AC blower pulling voltage down was created by jerry r
2002 Mercury Villager 3.3, my question is it possible for a bad blower fan , to pull charging voltage down to 12 volts. its drawing about 19 amps.
Last edit: 06 Jul 2019 22:54 by jerry r.

Please Log in or Create an account to join the conversation.

More
07 Jul 2019 00:12 - 07 Jul 2019 00:41 #31467 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic AC blower pulling voltage down
Fans take huge electrical load bit this sounds like an alternator issue, is the idle speed normal ?

There are simple tests you can do but before testing it is important to check the battery has a good level of charge.

You can check the level of charge by measuring the voltage across the battery with the engine and everything else switched off this is called the open circuit voltage.

With engine running you would not expect to see below 13v. At 13.1v all the electrical loads are just being met but the battery is not getting any charge put back into it at all.

To get a true reading either measure this voltage after the vehicle has been parked for a few hours or if the engine has running turn the engine off and turn on the lights for two minutes or so, then switch the lights off.

Doing this strips the surface (false) charge off the battery and you can now check the voltage across the battery, if you read more than 12.4v you can test the alternator.

Normally no matter how many electrical loads are on the voltage at idle speed should never be below the battery's open circuit voltage.

At idle speed with no extra electrical loads on battery voltage should normally be in the range 13.4 to 14.5. increase the RPM to 2000 to 3000 and the voltage may increase but not above 14.9 volts. Normally at 2,000 RPM or above on average expect to see 14.0 to 14.4 volts.

Now repeat the test but with the head lights on and heater blower on at medium speed voltage should not drop below 13.1v at any point.

Finally with the engine at about 2,000 to 3,000 quickly switch off the lights heater and any other electrical electrical loads, at no point should the battery voltage go above 14.9 volts.

" Welcome to the 21st"


Last edit: 07 Jul 2019 00:41 by Andy.MacFadyen.

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 01:21 - 07 Jul 2019 01:24 #31468 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
Strange thing is that ,I can turn on all other loads besides the blower that includes the rear defrost the voltage does not drop below . 13.4, the moment I turn on the blower with the lights on and that's all the voltage starts to drop below battery voltage.
Last edit: 07 Jul 2019 01:24 by jerry r.

Please Log in or Create an account to join the conversation.

More
07 Jul 2019 02:45 #31469 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic AC blower pulling voltage down

jerry r wrote: Strange thing is that ,I car but i turn on all other loads besides the blower that includes the rear defrost the voltage does not drop below . 13.4, the moment I turn on the blower with the lights on and that's all the voltage starts to drop below battery voltage.


Alternators on modern cars are rated in the 80 to 160 amp minimum so it shouldn't be an issue. Fan motors do tend to draw more current as they get older but if it was way over spec I would expect it to blow a fuse. I would assume it has the smart charge system.
I'm not that expert on Ford Smart charging systems but to me that looks an issue in the lternator itself, there is a by-pass test for the system I will use the Google machine and post it,.

" Welcome to the 21st"


Please Log in or Create an account to join the conversation.

More
07 Jul 2019 03:20 #31470 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic AC blower pulling voltage down
The quick and dirty check on the alternator is simply to disconnect the 3 pin connector with this discconnected the alternator should produce a constat 13.75v as log as it is meeting the load.

" Welcome to the 21st"


The following user(s) said Thank You: jerry r

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 07:28 #31471 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
I would assume it would blow the fuse also it seem that the rear defrost it rated at the same amps

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 07:50 #31473 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
it dropped to 12.9

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 08:05 #31474 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
seems like it only drops with the blower on ,but not with anything eles

Please Log in or Create an account to join the conversation.

  • Tyler
  • Tyler's Avatar
  • Offline
  • Moderator
  • Moderator
  • Letting the magic smoke out since 2011
More
07 Jul 2019 09:50 #31478 by Tyler
Replied by Tyler on topic AC blower pulling voltage down
Does it only dip into the 12V range with the blower on at idle? As in, you turn the blower on, and you start seeing 12.8/9 at the battery? Does the same reading improve if you raise the engine speed off idle?

Please Log in or Create an account to join the conversation.

More
07 Jul 2019 10:27 #31480 by Cheryl
Replied by Cheryl on topic AC blower pulling voltage down
Is the battery light coming on?? If it was mine and lights aren’t dimming it battery light is coming on I’d be fine.!

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 10:31 #31481 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
yes at idle with the blower on,yes is rises with rpm increase .now the indicator light isn't coming. looks a like another bad alternator ,brought 3 remans all bad, thats why I thought I was over looking something.

Please Log in or Create an account to join the conversation.

  • Tyler
  • Tyler's Avatar
  • Offline
  • Moderator
  • Moderator
  • Letting the magic smoke out since 2011
More
07 Jul 2019 10:42 #31482 by Tyler
Replied by Tyler on topic AC blower pulling voltage down
Try another brand, if you have one available? I dunno how labor intensive these are to replace.

Really, though, the behavior you're describing sounds fairly typical of Ford/Mercury products of that generation. Even the Nissan crossovers. ;) Almost none can stay above 13V with headlights and the blower on at idle. Raising the engine speed off idle allows the alternator to reach maximum output, which it usually can't do at idle.

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 11:19 - 07 Jul 2019 12:11 #31483 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
at times it dropped to 12.3 I believe it would keep dropping if I didn't turn the blower off. No indicator light is not coming on even with initial key on bulb check
Last edit: 07 Jul 2019 12:11 by jerry r.

Please Log in or Create an account to join the conversation.

  • Tyler
  • Tyler's Avatar
  • Offline
  • Moderator
  • Moderator
  • Letting the magic smoke out since 2011
More
07 Jul 2019 13:24 #31488 by Tyler
Replied by Tyler on topic AC blower pulling voltage down

jerry r wrote: No indicator light is not coming on even with initial key on bulb check


Was it always that way? Did did the indicator ever work with any of the other alternators?

How easy is it to get to the alternator connector?

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 15:27 #31497 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
yes it was working before. .I tested it and it works all the way from the back on the alternator.

Please Log in or Create an account to join the conversation.

  • Tyler
  • Tyler's Avatar
  • Offline
  • Moderator
  • Moderator
  • Letting the magic smoke out since 2011
More
07 Jul 2019 15:35 #31499 by Tyler
Replied by Tyler on topic AC blower pulling voltage down
You can make the charging indicator turn on from the alternator connector? Then your latest 'new' alternator sucks. :angry: :silly:
The following user(s) said Thank You: jerry r

Please Log in or Create an account to join the conversation.

  • jerry r
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Jul 2019 15:47 #31501 by jerry r
Replied by jerry r on topic AC blower pulling voltage down
yea it dose, but after a third one I started to doubt my ability

Please Log in or Create an account to join the conversation.

  • Not Allowed: to create new topic.
  • Not Allowed: to reply.
  • Not Allowed: to add attachements.
  • Not Allowed: to edit your message.
Time to create page: 0.800 seconds