Heater Motor
Thread Starter
Racer
Joined: Sep 2016
Posts: 312
Likes: 12
From: Tipton In.
Heater Motor
The heater motor in my 75 vette is starting to squeal whenever it is running so probably going to have to put a new one in. Question is how does one get to it to change it. Keep in mind the whole front is off an 80 model so it has the removable side vents behind the front wheel on the side fender. Does one remove the vent and go thru there or what. Nothing looks easy. Thanks Larry
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Mine is a '71 which also has a removable side vent, and that is the best way to do that job on my car. Hope your side vent is large enough to do the job. At least you have enough access to get an arm in there to use tools.
Be aware that the replacement motors for these fans are quite different than the originals. Most are much smaller. That, alone, is not a problem; but some are 'chinzy' and very inexpensive. Ask what those differences are between parts choices or purchase from a vendor that you think has the customer foremost in their interest.
Also, while you have that blower removed, you need to evaluate how much debris has collected in the plenum area. If there is some in there, this is the perfect opportunity to clean it out. Git 'er done!!
Be aware that the replacement motors for these fans are quite different than the originals. Most are much smaller. That, alone, is not a problem; but some are 'chinzy' and very inexpensive. Ask what those differences are between parts choices or purchase from a vendor that you think has the customer foremost in their interest.
Also, while you have that blower removed, you need to evaluate how much debris has collected in the plenum area. If there is some in there, this is the perfect opportunity to clean it out. Git 'er done!!
Last edited by 7T1vette; Jan 15, 2017 at 11:54 AM.
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
I did mine from the top on my '74. It's an A/C car too. I didn't think it was a bad job at all...knocked it out in about 30 minutes. You have to feel around for the bottom screw holding the blower to the case, but that's about the biggest speed bump I encountered on the replacement.
Man, I wish all the jobs I've done on this car were as easy to do as that one was.
Man, I wish all the jobs I've done on this car were as easy to do as that one was.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I remove the panel that joins the bottom of the fender to the rear portion of your inner skirt. Removal of the rocker panel will be required to gain access of two of the four bolts that you will remove. I know that this may seem like a waste of time...but for me it is faster because then I can jack up the car and see the bolts that I need to remove to get the motor out.
And when you go back in with it....it will go faster.
Sometimes removing the coolant over flow reservoir is also required so you can try to get the motor and fan to come out through the top...if not...then it will drop out through the bottom.
DUB
And when you go back in with it....it will go faster.
Sometimes removing the coolant over flow reservoir is also required so you can try to get the motor and fan to come out through the top...if not...then it will drop out through the bottom.
DUB
Thread Starter
Racer
Joined: Sep 2016
Posts: 312
Likes: 12
From: Tipton In.
I had googled it and it said to remove the overflow tank which I did. Wasn't to bad to get out. Now the question is do I want to install heater motor from an 86 for better airflow like some have done,
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
1)Cut and re-glass the motor housing deeper.
2)Machine and install a spacer.
I did the later.
Thread Starter
Racer
Joined: Sep 2016
Posts: 312
Likes: 12
From: Tipton In.
It's a good mod, but you have to do one of two things.
1)Cut and re-glass the motor housing deeper.
2)Machine and install a spacer.
I did the later.
Attachment 48054232
Attachment 48054233
1)Cut and re-glass the motor housing deeper.
2)Machine and install a spacer.
I did the later.
Attachment 48054232
Attachment 48054233
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Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Mine was machined out of nylon. Many people use wood and paint it. I would go with 7/8".
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I would stop and think about this for a second.
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
I DO KNOW that crap and leaves that can cover or block the front face of the evaporator core WILL effect how much air you get past it. And putting on a motor that is believed to be better may do something...or may not.
I have an air flow meter and I have tested a 1985 when I put on a new blower motor and evaporator core ...so I know what the CFM's are. I have the number for a 1974 with A/C and all new parts so there are no air obstructions. But I have yet to install the C4 motor and test it to verify if my suspicions are correct.
Needless to say...do whatever you like.
And you can look at the front face of the evaporator care once the blower motor is out of the car.
An 1984 or 1985 blower motor uses the same electrical connections. So no wiring modifications are needed.
DUB
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
I DO KNOW that crap and leaves that can cover or block the front face of the evaporator core WILL effect how much air you get past it. And putting on a motor that is believed to be better may do something...or may not.
I have an air flow meter and I have tested a 1985 when I put on a new blower motor and evaporator core ...so I know what the CFM's are. I have the number for a 1974 with A/C and all new parts so there are no air obstructions. But I have yet to install the C4 motor and test it to verify if my suspicions are correct.
Needless to say...do whatever you like.
And you can look at the front face of the evaporator care once the blower motor is out of the car.
An 1984 or 1985 blower motor uses the same electrical connections. So no wiring modifications are needed.
DUB
Last edited by DUB; Jan 16, 2017 at 07:10 PM.
Thread Starter
Racer
Joined: Sep 2016
Posts: 312
Likes: 12
From: Tipton In.
I would stop and think about this for a second.
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
I DO KNOW that crap and leaves that can cover or block the front face of the evaporator core WILL effect how much air you get past it. And putting on a motor that is believed to be better may do something...or may not.
I have an air flow meter and I have tested a 1985 when I put on a new blower motor and evaporator core ...so I know what the CFM's are. I have the number for a 1974 with A/C and all new parts so there are no air obstructions. But I have yet to install the C4 motor and test it to verify if my suspicions are correct.
Needless to say...do whatever you like.
And you can look at the front face of the evaporator care once the blower motor is out of the car.
An 1984 or 1985 blower motor uses the same electrical connections. So no wiring modifications are needed.
DUB
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
I DO KNOW that crap and leaves that can cover or block the front face of the evaporator core WILL effect how much air you get past it. And putting on a motor that is believed to be better may do something...or may not.
I have an air flow meter and I have tested a 1985 when I put on a new blower motor and evaporator core ...so I know what the CFM's are. I have the number for a 1974 with A/C and all new parts so there are no air obstructions. But I have yet to install the C4 motor and test it to verify if my suspicions are correct.
Needless to say...do whatever you like.
And you can look at the front face of the evaporator care once the blower motor is out of the car.
An 1984 or 1985 blower motor uses the same electrical connections. So no wiring modifications are needed.
DUB
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
I would stop and think about this for a second.
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
However, let me tell you, even with the spacer, the fan works better.
Maybe the blades, maybe its new, maybe its faster, but it IS better airflow than before.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
You could just remove the right side...but honestly I would get the left side off first and see if I could move the evaporator core and clean it and not have to mess with the right side where the blower motor mounts.
I know the evaporator core is secured to one of the halves if I am not mistaken...and that is why I think you want to get the left side off first. Heck..I might be confusion it with all the other stuff I have running around in my head all the time.
I will need to measure the air flow so I am totally convinced. I am sure there is a benefit...but I would like the 'dyno results' to confirm it without any doubts.
I did a 1970 that has the 85 blower motor in it and it has been thoroughly cleaned out. I should be gettign it back in the shop for a small issue and I will test it and see if the numbers are higher than the 74 I did that has the stock design blower motor in it.
DUB
I know the evaporator core is secured to one of the halves if I am not mistaken...and that is why I think you want to get the left side off first. Heck..I might be confusion it with all the other stuff I have running around in my head all the time.
I will need to measure the air flow so I am totally convinced. I am sure there is a benefit...but I would like the 'dyno results' to confirm it without any doubts.
I did a 1970 that has the 85 blower motor in it and it has been thoroughly cleaned out. I should be gettign it back in the shop for a small issue and I will test it and see if the numbers are higher than the 74 I did that has the stock design blower motor in it.
DUB
Thread Starter
Racer
Joined: Sep 2016
Posts: 312
Likes: 12
From: Tipton In.
You could just remove the right side...but honestly I would get the left side off first and see if I could move the evaporator core and clean it and not have to mess with the right side where the blower motor mounts.
I know the evaporator core is secured to one of the halves if I am not mistaken...and that is why I think you want to get the left side off first. Heck..I might be confusion it with all the other stuff I have running around in my head all the time.
I will need to measure the air flow so I am totally convinced. I am sure there is a benefit...but I would like the 'dyno results' to confirm it without any doubts.
I did a 1970 that has the 85 blower motor in it and it has been thoroughly cleaned out. I should be gettign it back in the shop for a small issue and I will test it and see if the numbers are higher than the 74 I did that has the stock design blower motor in it.
DUB
I know the evaporator core is secured to one of the halves if I am not mistaken...and that is why I think you want to get the left side off first. Heck..I might be confusion it with all the other stuff I have running around in my head all the time.
I will need to measure the air flow so I am totally convinced. I am sure there is a benefit...but I would like the 'dyno results' to confirm it without any doubts.
I did a 1970 that has the 85 blower motor in it and it has been thoroughly cleaned out. I should be gettign it back in the shop for a small issue and I will test it and see if the numbers are higher than the 74 I did that has the stock design blower motor in it.
DUB
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I would stop and think about this for a second.
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
I DO KNOW that crap and leaves that can cover or block the front face of the evaporator core WILL effect how much air you get past it. And putting on a motor that is believed to be better may do something...or may not.
I have an air flow meter and I have tested a 1985 when I put on a new blower motor and evaporator core ...so I know what the CFM's are. I have the number for a 1974 with A/C and all new parts so there are no air obstructions. But I have yet to install the C4 motor and test it to verify if my suspicions are correct.
Needless to say...do whatever you like.
And you can look at the front face of the evaporator care once the blower motor is out of the car.
An 1984 or 1985 blower motor uses the same electrical connections. So no wiring modifications are needed.
DUB
Knowing that the new motor is taller...thus needed a spacer. Then the area of the squirrel cage fan that is added...thus making us believe it is better....is now actually being blocked/restricted by the spacer and not allowing the same air flow function as the ones in the 1984-1996 design whose air box is made to accept the longer squirrel cage fan and thus allowing it to channel all the air.
I DO KNOW that crap and leaves that can cover or block the front face of the evaporator core WILL effect how much air you get past it. And putting on a motor that is believed to be better may do something...or may not.
I have an air flow meter and I have tested a 1985 when I put on a new blower motor and evaporator core ...so I know what the CFM's are. I have the number for a 1974 with A/C and all new parts so there are no air obstructions. But I have yet to install the C4 motor and test it to verify if my suspicions are correct.
Needless to say...do whatever you like.
And you can look at the front face of the evaporator care once the blower motor is out of the car.
An 1984 or 1985 blower motor uses the same electrical connections. So no wiring modifications are needed.
DUB
It's not the depth of the blades that increases the flow it's the angle of attack of the blades. They move air more efficiently than the old blade design.
I did this mod with the spacer and first time I turned it on it blew out bits and pieces of the ducting seal foam from the increased air flow.
I would say it's about 30% greater air flow than the stock unit. Just an estimate, I didn't measure it. If a person were to increase the depth of the box to accommodate the deeper fan I suspect it would be an even greater increase.
Last edited by REELAV8R; Jan 18, 2017 at 11:09 AM.
Race Director
Joined: Apr 2009
Posts: 19,294
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From: Charlotte NC
I get that the angle of the blade is what makes the difference....but I honestly can not remember 100% when I did that one if I looked at the fan blade pitch and I feel it was the same pitch and not angled differently to increase air flow.
I need to look at some stuff and might get back to this.
DUB
I need to look at some stuff and might get back to this.
DUB