HEATER/DEF problem!!

6

67staaang

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Mar 30, 2005

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Dec 6, 2005

#1

• Dec 6, 2005

• #1

hey guys. i am having trouble trying to figure out what is wrong with my heater/ defroster in my 67 mustang. it used to blow out air pretty good but now i slide the knob to high and it seems like its barely even on. there is some air coming out but not much. it sucks cause without a quick heater/defroster i have to open my window and freeze my A55 till my windshield gets clear. once im rolling along on the high way with my windows closed i can finally feel the hot air. SOMEONE HELP ME PLEEASSE!!! thanks guys.

 

6

67CoupeDriva

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Mar 15, 2004

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South Carolina

Dec 6, 2005

#2

• Dec 6, 2005

• #2

Is the fan actually blowing (you should be able to hear it)? If not, run through the usual electrical suspects...fuse, bad ground, bad switch, damaged wire, defunct motor. Do you have all 3 speeds for the fan?
If it IS, and you aren't feeling any wind, check to be sure the control cables are still connected to the air plenum, that the plenum is attached to the heater housing, your vent doors are closed. Those cables just operate little flaps in there to direct the air, so if they aren't working the fan may just be blowing against a wall.

 

6

67staaang

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Mar 30, 2005

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Dec 6, 2005

#3

• Dec 6, 2005

• #3

the fan is blowing but very low. yeah ill check wiring and fuse etc. yes i have all three speeds for the fan. ill check up on it. thanks. man

 

F

ForceFed70

That's why they call it "dope"

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Dec 6, 2005

#4

• Dec 6, 2005

• #4

If you can get a voltmeter on it, check the voltage at the blower with the switch set to high. You should see battery voltage (maybe 1v lower) so if you see 10V or more, then it's not a wiring problem. In which case it's probably time for a new blower motor.

 

6

67staaang

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Mar 30, 2005

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Dec 6, 2005

#5

• Dec 6, 2005

• #5

around how much is a new blower motor?

 

F

ForceFed70

That's why they call it "dope"

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#6

• Dec 6, 2005

• #6

67staaang said:

around how much is a new blower motor?

Click to expand...

Can't say I know... usually around $50. However, it's one of those parts that are fairly cheap to buy, but a real PITA to install/replace.

 

M

mustangdave

My rearend needs a stud and two nuts.

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Dec 6, 2005

#7

• Dec 6, 2005

• #7

Most likely your problem is the cardboard plenum needs to be replaced with the newer plastic version. The cardboard falls apart. You could also have a bad flapper door or broken tab where the cable connects.

 

6

67staaang

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Dec 7, 2005

#8

• Dec 7, 2005

• #8

sorry guys im new to this stuff. so where exactly is the cardboard plenum?

 

M

mustangdave

My rearend needs a stud and two nuts.

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Dec 7, 2005

#9

• Dec 7, 2005

• #9

Under the passenger side dash. I would replace it with a plastic one and buy a heater box rebuild kit. Also, check the hoses that come off of the box; they could be rotten and loose or disconnected.
The cardboard replacement is sold by almost all Mustang vendors and is only about $13.00. The hoses attach to it. A heater case rebuild kit is less than $10. It is all very hard to get to so I would also replace the heater core while I had it apart($30-$40). You can also buy replacement hoses though they are not an exact repro.

 

6

67CoupeDriva

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Dec 7, 2005

#10

• Dec 7, 2005

• #10

Another thought is the resistor to control the various motor speeds. If the motor is blowing, but too slowly you think, that resistor on the front of the heater casing could be bad. I'd suspect the motor first, but it's another thought. Good luck!

 

F

ForceFed70

That's why they call it "dope"

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Dec 7, 2005

#11

• Dec 7, 2005

• #11

67CoupeDriva said:

Another thought is the resistor to control the various motor speeds. If the motor is blowing, but too slowly you think, that resistor on the front of the heater casing could be bad. I'd suspect the motor first, but it's another thought. Good luck!

Click to expand...

But on the "high" setting, the resistor pac shouldn't be used. It should apply 12V straight to the blower motor.

I guess the best thing to do is to determine wether the blower is working properly. These old cars had noisy blowers... you should be able to tell just by the sound wether the blower motor is turning at a fast speed or not.

If the blower itself is spinning slowly, you have an electrical problem. If it's spinning quickly but very little air is comming out of the ducts then it's probably a blockage or another problem with the actual airflow (like the cardboard piece).

 

R

Ratdz

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May 3, 2005

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Dec 7, 2005

#12

• Dec 7, 2005

• #12

something else to check is maybe a napkin or paper towel has gotten into the "squirrel cage" and is blocking air flow.
I have seen it happen several times.

 

F

ForceFed70

That's why they call it "dope"

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#13

• Dec 7, 2005

• #13

Ratdz said:

something else to check is maybe a napkin or paper towel has gotten into the "squirrel cage" and is blocking air flow.
I have seen it happen several times.

Click to expand...

I had 1/2 a mouse nest in mine...

 

6

67staaang

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Dec 7, 2005

#14

• Dec 7, 2005

• #14

hey guys thanks for all your help and advice. just to clarify a little.. i have noticed that whether or not the heater is on low or high or even off i feel some air coming out of the defroster vents and the vent under the dash. im not really sure whats wrong. but the temp control does work though.. hm...

 

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ForceFed70

That's why they call it "dope"

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#15

• Dec 7, 2005

• #15

67staaang said:

hey guys thanks for all your help and advice. just to clarify a little.. i have noticed that whether or not the heater is on low or high or even off i feel some air coming out of the defroster vents and the vent under the dash. im not really sure whats wrong. but the temp control does work though.. hm...

Click to expand...

That's normal operation for when your fan isn't on. When driving air entering at the cowl is under pressure and wants to enter the passanger compartment which is at lower pressure. When your not driving the warm air from the heater core will rise and you can sometimes feal that air coming out of the vents. On full speed you should definately hear your fan if it's spinning. To me it sounds like your fan isn't spinning at all.

 

6

67staaang

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Mar 30, 2005

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Dec 8, 2005

#16

• Dec 8, 2005

• #16

yea before i used to at least here it spinning but now... NADA.

 

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ForceFed70

That's why they call it "dope"

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Dec 8, 2005

#17

• Dec 8, 2005

• #17

67staaang said:

yea before i used to at least here it spinning but now... NADA.

Click to expand...

Then your problem is do to 1 of 3 things:

1) Wiring to the blower.
2) The blower motor itself.
3) Something jamming the blower so it can't spin (which would cause your blower motor or wiring to burn out anyway)