TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > Body/Interior > HVAC
  New Posts New Posts RSS Feed - Getting more air out of the fan motor
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Getting more air out of the fan motor

 Post Reply Post Reply
Author
Message
Rambler Mexicano View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Mar/05/2011
Location: Guadalajara
Status: Offline
Points: 433
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Topic: Getting more air out of the fan motor
    Posted: Mar/16/2017 at 9:14pm
I don't know if it is the same case in the US as in Mexico, but the situation is as follows.

Regarding 1978-1983 cars with just the heater (non-Air Conditioning units), as far as I've been able to test them they have very weak fans.

The few times I've had to drive my 1981 Rally GT (1981 Spirit GT) in the rain, putting the temperature in Cool, the air ducts on Defroster and the fan at full speed, it feels almost useless. There's a very weak flow that takes too much time to defrost the windshield.

Is there a way to modifiy the fan into blowing MORE air? Like twice the amount of air it normally does. I do know that manufacturers kept the air flow weak to keep them from making noise and thus making the ride unconfortable.

I've asked people I know about it and I've had contradictory points of view.

Some say they fan motor is not the problem, it is the propeller. That I should keep the fan motor and change the propeller. Which can used? No clue.

Others tell me it is the fan motor that causes the problem, that I should have it replaced or change the coils inside for different more powerful units.

What can I do.

Thanks in advance for any help you can provide.

PS

I have been able to check actual Air Conditioning-equipped AMC/VAM cars, but I do have the impression their fans are different. I have seen a hose in those fans that is not present in the NON-AC units. I would like to think they're more powerful.

What is the hose for?

Are they more powerful?
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
Back to Top
pit crew View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jul/08/2007
Location: NE Ohio
Status: Offline
Points: 4167
Post Options Post Options   Thanks (1) Thanks(1)   Quote pit crew Quote  Post ReplyReply Direct Link To This Post Posted: Mar/17/2017 at 8:24am
What I have observed is on non-AC cars the fan is supplied power through a resistor located on the firewall or in the heater box. The fan switch changes how much of the resistor is used to provide multi speeds. In some of the AC cars the high speed blower setting bypasses the resistor and engages a relay that supplies direct battery voltage to the blower motor. In theory the short hose you see bleeds off some air flow from the fan to cool the blower motor.

With that said most non-AC cars had a blower that delivered pretty good air flow. I would double check the control cables and the blend doors to make sure they are adjusted correctly and directing full air flow before I would tackle the blower motor.


Edited by pit crew - Mar/17/2017 at 8:27am
Back to Top
6PakBee View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jul/01/2007
Location: North Dakota
Status: Offline
Points: 2847
Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Mar/17/2017 at 10:22am
You've got to watch what you are doing with fans.  For a constant speed and a fixed impeller size/design, if you increase airflow by decreasing pressure drop, the % increase in power required is pretty much the same % increase in airflow.  If you try increasing airflow by increasing speed or increasing the diameter or width of the wheel, the horsepower required is a cube function.  You can easily overload the motor.  One of my friends with a Kenworth road tractor, against my recommendations, put bigger wheels on his heater blower.  Started popping fuses, went to larger fuses, burnt the motor out.  I agree with the other suggestions, make sure all your damper doors are set up correctly and that you don't have debris blocking your heat or A/C cores.
The difference between people and AMC's is that they will always be making more people; they won't be making more AMC's

Roger



Back to Top
83GT View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Aug/03/2014
Location: Galveston TX
Status: Offline
Points: 357
Post Options Post Options   Thanks (0) Thanks(0)   Quote 83GT Quote  Post ReplyReply Direct Link To This Post Posted: Mar/17/2017 at 11:48am
Originally posted by pit crew pit crew wrote:

I would double check the control cables and the blend doors to make sure they are adjusted correctly and directing full air flow before I would tackle the blower motor.

X2
1983 Spirit GT   258 4-speed
1979 Datsun Sunline Solaris RV
Back to Top
6768rogues View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/03/2007
Location: United States
Status: Offline
Points: 4359
Post Options Post Options   Thanks (0) Thanks(0)   Quote 6768rogues Quote  Post ReplyReply Direct Link To This Post Posted: Mar/17/2017 at 7:17pm
I have seen motors with a resistor to vary speed and others with two sets of windings to provide two speeds. The first thing I would check is to make sure the fan is actually running in high speed.
Why Ramblers? Chicks dig 'em. Whatever it is, I can take it apart.
Located near Rochester, NY
Back to Top
White70JavelinSST View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/08/2012
Location: Minnesota
Status: Offline
Points: 2603
Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Mar/28/2017 at 10:06am
The design of the air delivery system is not flawed from the factory. I live in MN, USA, where the temperatures range from 25 degrees Fahrenheit below zero and 100 degrees Fahrenheit above zero. High humidity also. Back in the early 1970s when I had no choice but to use the Javelin during the winter and summer bad weather days, the blower speeds were never an issue. Your problem lies elsewhere. Like the other posters have stated, check the simple things first. Get a TSM, study the HVAC system section and get familiar with how it works.  
70 Javelin SST, second owner, purchased 1972
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 13774
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Aug/31/2017 at 8:05am
Two speed winding motors (two wire, grounds through case... replacements may have a ground wire) were generally used in non-AC cars. Single speed (one wire... again, replacements may have a ground wire...) were used with AC with resistors to supply two lower speeds. You can get Heavy Duty replacements from school bus parts suppliers. You need to measure the shaft size on the original. You may have to drill the mounting holes or change spacing to mount the HD motor though.
Frank Swygert
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.062 seconds.
All content of this site Copyright © 2012 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or